Product Capability / In-App Payment / Development Guidelines

Development Guidelines

1. API Rules

In order to provide a simple, consistent and easy-to-use development experience to merchants while ensuring payment security, we have launched the latest WeChat Pay APIv3 interface. Please refer to “APIv3 Interface Rules” for the specific rules of this API version.

2. Development Environment Setup

To help developers call the open interface, the development libraries of Java、PHP、GO are provided, encapsulating the basic functions such as signature generation, signature verification, encryption/decryption of sensitive information, and media document upload

JAVA Golang PHP

2.1.1. Conditions of Use

• WechatPay merchant account

• Java 1.8 or later

• Maven or Gradle;

• 0.4.6 or later version of the Java httpClient SDK

2.1.2. Installation

Gradle：Add the following dependencies to your build.gradle document

implementation 'com.github.wechatpay-apiv3:wechatpay-apache-httpclient:0.4.7'

Maven：Add the following dependencies to the pom.xml document

<dependency>
<groupId>com.github.wechatpay-apiv3</groupId>
<artifactId>wechatpay-apache-httpclient</artifactId>
<version>0.4.7</version>
</dependency>

2.1.3. Initialization

Initialize WechatPayHttpClientBuilder to create an httpClient, which will be used to send requests to call the WeChatPay interface. Initialize a verifier instance with CertificatesManager to verify the signature.


    private CloseableHttpClient httpClient;
    private CertificatesManager certificatesManager;
    private Verifier verifier;

    @Before
    //initialize verifier and build httpClient
    public void setup() throws GeneralSecurityException, IOException, HttpCodeException, NotFoundException {

        PrivateKey merchantPrivateKey = PemUtil.loadPrivateKey(privateKey);
        certificatesManager = CertificatesManager.getInstance();
        certificatesManager.putMerchant(merchantId, new WechatPay2Credentials(merchantId,
                        new PrivateKeySigner(merchantSerialNumber, merchantPrivateKey)),
                apiV3Key.getBytes(StandardCharsets.UTF_8));
        verifier = certificatesManager.getVerifier(merchantId);
        WechatPayHttpClientBuilder builder = WechatPayHttpClientBuilder.create()
                .withMerchant(merchantId, merchantSerialNumber, merchantPrivateKey)
                .withValidator(new WechatPay2Validator(verifier));
        httpClient = builder.build();
    }

2.1.4. General Functions

Encrypting Sensitive Information Decrypting Sensitive Information


    @Test
    public void encryptedTest() throws IllegalBlockSizeException {
        String text = "helloWorld";
        String transformation = "RSA/ECB/PKCS1Padding";
        String encryptedText = RsaCryptoUtil.encrypt(text, verifier.getValidCertificate(), transformation);
        System.out.println(encryptedText);
    }


    @Test
    public void decryptedTest() throws BadPaddingException {
        String encryptedText = OBTgun4jiN13n3nmSg8v0MNDMy3mbs380yq4GrgO8vwCqXnvrWxwo3jUCNY2UY7MIOtv/SD8ke64MxcSB0hn5EzKv1LOLprI3NvvmNLS4C3SBulxpZG62RYp1+8FgwAI4M//icXvjtZWVH4KVDg==";
        String transformation = "RSA/ECB/PKCS1Padding";
        String decryptedText = RsaCryptoUtil.decrypt(encryptedText, PemUtil.loadPrivateKey(privateKey), transformation);
        assert("helloWorld".equals(decryptedText));
    }

2.2.1. Conditions of Use

• WechatPay merchant account

• GO SDK 0.2.13 or later version

2.2.2. Installation

1. Manage your projects with Go Modules

If Go Modules are not used for the dependency management of your projects, run in the project root directory:

go mod init

2. Without cloning the code in the repository, run directly in the project directory:

go get -u github.com/wechatpay-apiv3/wechatpay-go

to add a dependency, modify modand download SDK

2.2.3. Initialization

Initialize Client and load the merchant account, private key, API V3 key, merchant certificate and serial number to Client for sending an interface request later.


import (
   "context"
   "crypto/rand"
   "crypto/rsa"
   "crypto/x509"
   "encoding/base64"
   "fmt"
   "github.com/wechatpay-apiv3/wechatpay-go/core"
   "github.com/wechatpay-apiv3/wechatpay-go/core/option"
   "github.com/wechatpay-apiv3/wechatpay-go/utils"
   "log"
   "net/http"
)

var (
   mchID                      = ""                  // merchant id
   mchCertificateSerialNumber = "" // merchant certificate serial number
   mchAPIv3Key                = ""                  // merchant api v3 key
   header                     = make(http.Header)
   ctx                        = context.Background()
   cert                       *x509.Certificate
   mchPrivateKey              *rsa.PrivateKey
   client                     *core.Client
   err                        error
)

func setup() {
   //Load platform certificate
   cert, err = utils.LoadCertificateWithPath("Path/To/Platform/Cert")
   if err != nil {
      log.Fatal(err)
   }
   // Load private key
   mchPrivateKey, err = utils.LoadPrivateKeyWithPath("Path/To/Private/Key")
   if err != nil {
      log.Fatal("load merchant private key error")
   }
   // Initialize client which is capable to update platform certificate periodically
   opts := []core.ClientOption{
      option.WithWechatPayAutoAuthCipher(mchID, mchCertificateSerialNumber, mchPrivateKey, mchAPIv3Key),
   }
   client, err = core.NewClient(ctx, opts...)
   if err != nil {
      log.Fatalf("new wechat pay client err:%s", err)
   }
}

2.2.4. General Functions

Encrypting Sensitive Information Decrypting Sensitive Information


func Encryption(t *testing.T) {
	var testRSACryptoUtilMchCertificateStr = `-----BEGIN CERTIFICATE-----
	-----END CERTIFICATE-----`
	testRSACryptoUtilCertificate, _ = LoadCertificate(testRSACryptoUtilMchCertificateStr)
   const message = "hello world"
   
   // Encrypt the certificate by OAEP padding
   ciphertext, _ := EncryptOAEPWithCertificate(message, testRSACryptoUtilCertificate)
   
  // Encrypt the certificate by PKCS1 padding
   ciphertext, _ := EncryptPKCS1v15WithCertificate(message, testRSACryptoUtilCertificate)
}


func TestDecryption(t *testing.T) {
	var testRSACryptoUtilPrivateKeyStr = `-----BEGIN PRIVATE KEY-----
-----END PRIVATE KEY-----`
	testRSACryptoUtilPrivateKey, _ = LoadPrivateKey(testingKey(testRSACryptoUtilPrivateKeyStr))
	const ciphertext = ""

	// Decrypt the private key by PKCS1 padding
	decryptMessage, _ := DecryptPKCS1v15(ciphertext, testRSACryptoUtilPrivateKey)

	// Decrypt the private key by OAEP padding
	decryptMessage, _ := DecryptOAEP(ciphertext, testRSACryptoUtilPrivateKey)
}

2.3.1. Conditions of Use

• Guzzle 7.0，PHP >= 7.2.5

• Guzzle 6.5，PHP >= 7.1.2

• PHP 8 is supported.

2.3.2. Installation

It is recommended to use the PHP package management tool Composer to install SDK:

composer require wechatpay/wechatpay

2.3.3. Initialization

Initialize Client and load the merchant account, private key, API V3 key, merchant certificate and serial number to Client in order to send an interface request later.


require_once('vendor/autoload.php');

use WeChatPay\Builder;
use WeChatPay\Crypto\Rsa;
use WeChatPay\Util\PemUtil;

$merchantId = '190000****';
$merchantPrivateKeyFilePath = 'file:///path/to/merchant/apiclient_key.pem';
$merchantPrivateKeyInstance = Rsa::from($merchantPrivateKeyFilePath, Rsa::KEY_TYPE_PRIVATE);
$merchantCertificateSerial = '3775B6A45ACD588826D15E583A95F5DD********';
$platformCertificateFilePath = 'file:///path/to/wechatpay/cert.pem';
$platformPublicKeyInstance = Rsa::from($platformCertificateFilePath, Rsa::KEY_TYPE_PUBLIC);
$platformCertificateSerial = PemUtil::parseCertificateSerialNo($platformCertificateFilePath);

// init a API V3 instance
$instance = Builder::factory([
    'mchid'      => $merchantId,
    'serial'     => $merchantCertificateSerial,
    'privateKey' => $merchantPrivateKeyInstance,
    'certs'      => [
        $platformCertificateSerial => $platformPublicKeyInstance,
    ],
]);

2.3.4. General Functions

Encrypting Sensitive Information Decrypting Sensitive Information


    $encryptor = static function(string $msg) use ($platformPublicKeyInstance): string {
        return Rsa::encrypt($msg, $platformPublicKeyInstance, OPENSSL_PKCS1_PADDING);
    };
	$encryptedMsg =  $encryptor('HelloWorld');


    $decryptor = static function(string $msg) use ($merchantPrivateKeyInstance): string {
        return Rsa::decrypt($msg, $merchantPrivateKeyInstance, OPENSSL_PKCS1_PADDING);
    };
	$decryptedMsg =  $decryptor('ciphertext');

2.4. Key Points of iOS Development

Key Points of iOS Development Key Points of Andriod Development

I. OpenSDK Upgrade Guidelines for iOS

Due to Apple's recall of the ability to query the App bundleID in iOS13, there is no guarantee that the authorization credentials will be correctly returned by WeChat to the App corresponding to the AppID. For this reason, WeChat Pay strongly requests all merchants to upgrade to OpenSDK 1.8.6 as soon as possible and cause users to update the APP in time, otherwise security risks will always exist. Thanks for your cooperation!

For the detailed OpenSDK Upgrade Guidelines, please refer to OpenSDK Upgrade Guidelines

Notice

• After OpenSDK is upgraded, be sure to complete the verification according to the document requirements, and ensure that the OpenSDK has been upgraded successfully.

II. Development Configuration:

The Xcode 6.0 and IOS 7.0 are taken as the examples for project development environment and operating environment respectively, to introduce the operation necessary for development

1. Set Project APPID

After the merchant applies for APP development at WeChat Open Platform, WeChat Open Platform will generate APP's unique identification, i.e., APPID. Open the project in Xcode and set the URL Schemes in the project properties as your APPID. Indicated as the red position in the figure

2. Register APPID

The merchant APP project introduces the WeChat lib library and header file. Before calling API, register your APPID with WeChat first. The code is as follows:

   [WXApi registerApp：@"wxd930ea5d5a258f4f" withDescription：@"demo 2.0"];

Notice

For instructions related to OpenSDK front-end pull-up payments and SDK callbacks

I. Background Settings

After the merchant applies for application development at WeChat Open Platform, WeChat Open Platform will generate APP's unique identification, i.e., APPID. To ensure payment security, bind the merchant application package name and application signature in the open platform, and set them up to initiate payment normally. Enter the [Management Center / Modify Application / Modify Development Information] in the [Open Platform] to access the setting screen, as shown in the red box in the figure.

Application package name is the package value declared in the APP project configuration file AndroidManifest.xml, such as package="demo.wxpay.tenpay.com” in the above figure.

Application signature is the keystore used according to the application package name and compilation of the project,consisting of a 32-bit md5 string generated by the signature tool. The application signature string can be

generated by the signature tool after installing the signature tool on the debugged mobile phone, as shown in Figure 8.9, which is in green.Download Address of Signature Tool

II. Register APPID

The merchant APP project introduces the WeChat JAR package. Before calling API, register your APPID with WeChat first. The code is as follows:

final IWXAPI msgApi = WXAPIFactory.createWXAPI(context, null);

// Resgiter this app with WeChat

msgApi.registerApp("wxd930ea5d5a258f4f");

Notice

For instructions related to OpenSDK front-end pull-up payments and SDK callbacks

3. Fast Access

3.1. Business Sequence Chart

3.2. Example of API access

The document shows how to use the WeChat Pay server SDK to In-App Payment by scanning code and interface with WeChat Pay.

Notice

• The code examples in the document illustrate the basic usage of API. Before running the code, the example parameters in the code need to be replaced with the merchant's own account and request parameters.

• The access steps below are for your information, and should be evaluated and modified according to the merchant’s own business demands.

3.2.1 Place an order

Procedure: Submit a pre-order request for In-APP payment through this interface, obtain the prepay_id to call payment.

Code example

JAVA Go PHP


 @Test
    //Call Unified Order API
    public void unifiedOrderTest() throws IOException {
      String unifiedOrderBody = String.join("\n" ,
                		"{" ,
                        "'sp_appid': 'wx2421b1c4370ec43b'," ,
                        "'sp_mchid': '10000100'," ,
                        "'sub_mchid': '20000100'," ,
                        "'sub_appid': 'wx352671b037b437ec'," ,
                        "'out_trade_no': '20150806125346'," ,
                        "'merchant_category_code': '1011'," ,
                        "'payer': {" ,
                        "'sp_openid': 'oUpF8uMuAJO_M2pxb1Q9zNjWeS6o'" ,
                        "}," ,
                        "'notify_url': 'https://wxpay.wxutil.com/pub_v2/pay/notify.v2.php'," ,
                        "'trade_type': 'APP'," ,
                        "'amount': {" ,
                        "'total': 10000," ,
                        "'currency': 'HKD'" ,
                        "}," ,
                        "'attach': 'Payment test'," ,
                        "'description': 'In-APP Pay test'," ,
                        "'goods_tag': '," ,
                        "'detail': {" ,
                        "'cost_price': 10000," ,
                        "'receipt_id': '1234'," ,
                        "'goods_detail': [{" ,
                        "'goods_id': 'iphone6s_16G'," ,
                        "'wxpay_goods_id': '1001'," ,
                        "'goods_name': 'iPhone6s 16G'," ,
                        "'quantity': 1," ,
                        "'price': 528800" ,
                        "}]" ,
                        "}," ,
                        "'scene_info': {" ,
                        "'payer_client_ip': '14.23.150.211'," ,
                        "'device_ip': '59.37.125.32'," ,
                        "'device_id': '013467007045764'," ,
                        "'operator_id': 'P001'," ,
                        "'store_info': {" ,
                        "'id': 'SZTX001'" ,
                        "}" ,
                        "}" ,
                        "}").replace("'","\"");
        HttpPost httpPost = new HttpPost("https://apihk.mch.weixin.qq.com/v3/global/transactions/app");
        httpPost.addHeader("Accept", "application/json");
        httpPost.addHeader("Content-type", "application/json; charset=utf-8");
        httpPost.setEntity(new StringEntity(unifiedOrderBody));
        CloseableHttpResponse response = httpClient.execute(httpPost);
        //Process the response
    }


//Call unified order API
func unifiedOrder() {
   orderRequestBody := `{
	"sp_appid": "wx2421b1c4370ec43b",
	"sp_mchid": "10000100",
	"sub_mchid": "20000100",
	"sub_appid": "wx352671b037b437ec",
	"out_trade_no": "20150806125346",
	"merchant_category_code": "1011",
	"payer": {
		"sp_openid": "oUpF8uMuAJO_M2pxb1Q9zNjWeS6o"
	},
	"notify_url": "https://wxpay.wxutil.com/pub_v2/pay/notify.v2.php",
	"trade_type": "APP",
	"amount": {
		"total": 10000,
		"currency": "HKD"
	},
	"attach": "Payment test",
	"description": "In-APP Pay test",
	"goods_tag": "",
	"detail": {
		"cost_price": 10000,
		"receipt_id": "1234",
		"goods_detail": [{
			"goods_id": "iphone6s_16G",
			"wxpay_goods_id": "1001",
			"goods_name": "iPhone6s 16G",
			"quantity": 1,
			"price": 528800
		}]
	},
	"scene_info": {
		"payer_client_ip": "14.23.150.211",
		"device_ip": "59.37.125.32",
		"device_id": "013467007045764",
		"operator_id": "P001",
		"store_info": {
			"id": "SZTX001"
		}
	}
}`
   result, err := client.Post(ctx, "https://apihk.mch.weixin.qq.com/v3/global/transactions/app", orderRequestBody)
   if err != nil {
      // Process error
   }
   log.Printf("status=%d resp=%s", result.Response.StatusCode, result.Response.Body)
}


// Call Unified Order API
public function unifiedOrder($instance){
    try {
        $resp = $instance
            ->chain('v3/global/transactions/app')
            ->post(['json' => [
                'sp_appid'     => 'wxdace645e0bc2c424',
                'sp_mchid'     => '10000100',
                'sub_mchid'    => '20000100',
				'sub_appid'		=> 'wx352671b037b437ec',
                'out_trade_no' => 'YX201710140020Z',
                'merchant_category_code' => '4111',
                'notify_url'   => 'https://weixin.qq.com/',
                'trade_type'   => 'APP',
                'amount'       => [
                    'total'    => 1,
                    'currency' => 'USD'
                ],	
				'payer'			=> [
					'sub_openid' => 'oUpF8uMuAJO_M2pxb1Q9zNjWeS6o'
				],
                'attach'  => 'mini-program payment test',
                'description'  => 'Image形象店-深圳腾大-QQ公仔',
                'goods_tag'  => '001'
            ]]);

        echo $resp->getStatusCode(), PHP_EOL;
        echo $resp->getBody(), PHP_EOL;
    } catch (Exception $e) {
        // EXception handling
        echo $e->getMessage(), PHP_EOL;
        if ($e instanceof \GuzzleHttp\Exception\RequestException && $e->hasResponse()) {
            $r = $e->getResponse();
            echo $r->getStatusCode() . ' ' . $r->getReasonPhrase(), PHP_EOL;
            echo $r->getBody(), PHP_EOL, PHP_EOL, PHP_EOL;
        }
        echo $e->getTraceAsString(), PHP_EOL;
    }
}


									{
										"stock_id": "Python",
										"stock_creator_mchid": "123456",
										"limit": 10,
									}

Critical parameters:

notify_url: For the address used to receive the asynchronous payment result callback notification, the notification URL must be a URL that is accessible by the external network and cannot carry any parameters. Please use an HTTPS protocol link

out_trade_no: internal order ID in merchant’s system

Please refer to the API document for ordering by scanning code for other critical parameters.

3.2.2 APP Pull-up Payment

Procedure: Get the necessary parameter prepay_id to initiate payment through the APP payment order interface, and use the SDK provided by WeChat Pay to pull up APP payment according to the rules in the interface definition.

The APP Pull-up Payment parameters must be calculated according to the signature rules:

Construct Signature String

   There are four lines in the signature string, and each line is a parameter. Each line ends with \n (Newline character; the ASCII code value is 0x0A), and even the last line shall ends with \n.If the parameter itself ends with \n, an additional \n is also required

Fields and formats involved in the signature:

   APPID
   Timestamp
   Random string
   Prepayment transaction session

Data Example:

   wx8888888888888888
   1414561699
   5K8264ILTKch16CQ2502SI8ZNMTM67VS
   WX1217752501201407033233368018

Calculate Signature Value：

The signature functions provided by most programming languages support signature data for signing. It is recommended that merchants call such functions, use the merchant's private key to sign the signature string with SHA256 with RSA, and perform Base64 encoding on the signature result to obtain the signature value.
Here we use command lines to demonstrate how to generate a signature.

$ echo -n -e \
"wx8888888888888888\n1414561699\n5K8264ILTKCH16CQ2502SI8ZNMTM67VS\nWX1217752501201407033233368018\n" \
  | openssl dgst -sha256 -sign apiclient_key.pem \
  | openssl base64 -A
  uOVRnA4qG/MNnYzdQxJanN+zU+lTgIcnU9Bx7cob8H/4nLBiCwIUFluw==

Code example

IOS Android

PayReq *request = [[[PayReq alloc] init] autorelease];
request.partnerId = @"10000100";
request.prepayId= @"1101000000140415649af9fc314aa427";
request.package = @"Sign=WXPay";
request.nonceStr= @"a462b76e7436e98e0ed6e13c64b4fd1c";
request.timeStamp= @"1397527777";
request.sign= @"oR9d8PuhnIc+YZ8cBHFCwfgpaK9gd7vaRvkYD7rthRAZ\/X+QBhcCYL21N7cHCTUxbQ+EAt6Uy+lwSN22f5YZvI45MLko8Pfso0jm46v5hqcVwrk6uddkGuT+Cdvu4WBqDzaDjnNa5UK3GfE1Wfl2gHxIIY5lLdUgWFts17D4WuolLLkiFZV+JSHMvH7eaLdT9N5GBovBwu5yYKUR7skR8Fu+LozcSqQixnlEZUfyE55feLOQTUYzLmR9pNtPbPsu6WVhbNHMS3Ss2+AehHvz+n64GDmXxbX++IOBvm2olHu3PsOUGRwhudhVf7UcGcunXt8cqNjKNqZLhLw4jq\/xDg==";
[WXApi sendReq：request];

IWXAPI api;
PayReq request = new PayReq();
request.appId = "wxd930ea5d5a258f4f";
request.partnerId = "1900000109";
request.prepayId= "1101000000140415649af9fc314aa427",;
request.packageValue = "Sign=WXPay";
request.nonceStr= "1101000000140429eb40476f8896f4c9";
request.timeStamp= "1398746574";
request.sign= "oR9d8PuhnIc+YZ8cBHFCwfgpaK9gd7vaRvkYDSs2+AehHvz+n64GDmXxbX++IOBvm2olHu3PsOUGRwhudhVf7UcGcunXt8cqNjKNqZLhLw4jq\/xDg==";
api.sendReq(request);

Critical parameters:

paySign: constructed payment signature

package：Specify as the static value “Sign=WXPay”

Please refer to the API document for ordering by scanning code for other critical parameters.

3.2.3 Query

Procedure: The merchant is required to take the initiative to check the order status after placing an order for a certain period of time.

Code example:

JAVA Go PHP


    @Test
    //Call query order API
    public void queryOrderTest() throws IOException {
        HttpGet httpGet = new HttpGet("https://apihk.mch.weixin.qq.com/v3/global/transactions/id/" +
                "4200123456789000?sub_mchid=100012321&sp_mchid=1900000000");
        httpGet.addHeader("Accept", "application/json");
        httpGet.addHeader("Content-type", "application/json; charset=utf-8");
        CloseableHttpResponse response = httpClient.execute(httpGet);
        //Process the response 
    }


//Call query order API
func queryOrder() {
   result, err := client.Get(ctx, "https://apihk.mch.weixin.qq.com/v3/global/transactions/id/4200000000000000?sub_mchid=100012321&sp_mchid=1900000000")
   if err != nil {
      // Process error
   }
   log.Printf("status=%d resp=%s", result.Response.StatusCode, result.Response.Body)
}


// Call query order API
public function queryOrder($instance)
{
    try {
        $resp = $instance
            ->v3->global->transactions->outTradeNo->_out_trade_no_
            ->get([
                    'query' => [
                'sp_mchid'     => '1900000000',
                'sub_mchid'    => '100012321',
                    ],
                    'out_trade_no' => 'YX0001'
                ]
            );

        echo $resp->getStatusCode(), PHP_EOL;
        echo $resp->getBody(), PHP_EOL;
    } catch (Exception $e) {
        // Exception handling
	}
}


									{
										"stock_id": "Python",
										"stock_creator_mchid": "123456",
										"limit": 10,
									}

Critical parameters:

id: WeChat payment order ID

out_trade_no: internal order ID in merchant’s system

Query with any order ID above. Please refer to the API document for ordering by scanning code for other critical parameters.

3.2.4 Refund

Procedure: After the payment is completed and the payment status is SUCCESS, call this interface to submit a refund request.

Code example

JAVA Go PHP


    @Test
    //Call Refund API
    public void refundTest() throws IOException {
		String refundBody = String.join("\n" ,
                		"{" ,
                        "'sp_appid': 'wx2421b1c4370ec43b', " ,
                        "'sp_mchid': '10000100'," ,
                        "'sub_mchid': '20000100'," ,
                        "'transaction_id': '1008450740201411110005820873'," ,
                        "'out_refund_no': 'R20150806125346'," ,
                        "    'amount' : {" ,
                        "        'refund': 5," ,
                        "        'total':10," ,
                        "         'currency':'HKD'" ,
                        "    }," ,
                        "    'reason': 'The item has been sold out.'," ,
                        "    'source': 'REFUND_SOURCE_UNSETTLED_FUNDS'" ,
                        "}").replace("'","\"");
        HttpPost httpPost = new HttpPost("https://apihk.mch.weixin.qq.com/v3/global/refunds");
        httpPost.addHeader("Accept", "application/json");
        httpPost.addHeader("Content-type", "application/json; charset=utf-8");
        httpPost.setEntity(new StringEntity(refundBody));
        CloseableHttpResponse response = httpClient.execute(httpPost);
        //Process the response 
    }


func refund() {
   refundRequestBody := `{
    "sp_appid": "wx2421b1c4370ec43b",
    "sp_mchid": "10000100",
    "sub_mchid": "20000100",
    "transaction_id": "1008450740201411110005820873",
    "out_refund_no": "R20150806125346",
    "amount" : {
        "refund": 50,
        "total":100,
         "currency":"HKD"
    },
    "reason": "The item has been sold out",
    "source": "REFUND_SOURCE_UNSETTLED_FUNDS"
}`
   result, err := client.Post(ctx, "https://apihk.mch.weixin.qq.com/v3/global/refunds", refundRequestBody)
   if err != nil {
      // Process error
   }
   log.Printf("status=%d resp=%s", result.Response.StatusCode, result.Response.Body)
}


// Call Refund API
public function refundOrder($instance){
    try {
        $resp = $instance
            ->chain('v3/global/refunds')
            ->post(['json' => [
                'sp_appid'     => 'wxdace12300000000',
                'sp_mchid'     => '1900000000',
                'sub_mchid'    => '100012321',
                'out_trade_no' => 'YX0001',
                "out_refund_no"=> "REFUNDYX0001",
                'amount'       => [
                    'refund'   => 1,
                    'total'    => 1,
                    'currency' => 'USD'
                ]
            ]]);
        echo $resp->getStatusCode(), PHP_EOL;
        echo $resp->getBody(), PHP_EOL;
    } catch (Exception $e) {
        // Exception handling
    }
}


									{
										"stock_id": "Python",
										"stock_creator_mchid": "123456",
										"limit": 10,
									}

Critical parameters:

out_trade_no: internal order ID in merchant’s system

transaction_id: WeChat order ID

out_refund_no: internal refund No. in merchant’s system, which should correspond to order ID

notify_url: address for receiving refund results

Please refer to the API document for ordering by scanning code for other critical parameters.

3.2.5 Query one refund

Procedure: After submitting a refund request, query the refund status by calling this interface.

Code example

JAVA Go PHP


    @Test
    //Call Query Refund API
    public void querySingleRefundTest() throws IOException {
        HttpGet httpGet = new HttpGet("https://apihk.mch.weixin.qq.com/v3/global/refunds/out-refund-no/RYX001?sub_mchid=100012321&sp_mchid=1900000000");
        httpGet.addHeader("Accept", "application/json");
        httpGet.addHeader("Content-type", "application/json; charset=utf-8");
        CloseableHttpResponse response = httpClient.execute(httpGet);
        //Process the response 
    }


//Query single refund API
func querySingleRefund() {
   result, err := client.Get(ctx, "https://apihk.mch.weixin.qq.com/v3/global/refunds/out-refund-no/REFUNDYX001?sub_mchid=100012321&sp_mchid=1900000000")
   if err != nil {
      // Process error
   }
   log.Printf("status=%d resp=%s", result.Response.StatusCode, result.Response.Body)
}


// Call Query Refund API
public function queryRefund($instance){
    try {
        $resp = $instance
            ->v3->global->refunds->outRefundNo->_out_refund_no_
            ->get([
                'query' => [
                    'sp_mchid' => '1900000000',
                    'sub_mchid'=> '100012321'
                ],
                'out_refund_no' => 'REFUNDYX0001'
            ]);

        echo $resp->getStatusCode(), PHP_EOL;
        echo $resp->getBody(), PHP_EOL;
    } catch (Exception $e) {
        // Exception handling
    }
}


									{
										"stock_id": "Python",
										"stock_creator_mchid": "123456",
										"limit": 10,
									}

Critical parameters:

out_trade_no: internal refund No. in merchant’s system

refund_id：WeChat payment refund order ID

Please refer to the API document for ordering by scanning code for other critical parameters.

3.2.6 Query all refunds

Procedure: After submitting a refund request, query all refund information corresponding to one payment order.

Code example

JAVA Go PHP


    @Test
    //Call Query All Refund API
    public void queryAllRefundTest() throws IOException {
        HttpGet httpGet = new HttpGet("https://apihk.mch.weixin.qq.com/v3/global/refunds" +
                "?out_trade_no=YX202111100020&count=10&offset=0&sp_mchid=1900000000&sub_mchid=100012321");
        httpGet.addHeader("Accept", "application/json");
        httpGet.addHeader("Content-type", "application/json; charset=utf-8");
        CloseableHttpResponse response = httpClient.execute(httpGet);
        //Process the response 
    }


//Query all refund API
func queryAllRefund() {
   result, err := client.Get(ctx, "https://apihk.mch.weixin.qq.com/v3/global/refunds/out-refund-no/out_trade_no=YX001&count=10&offset=0&sp_mchid=1900000000&sub_mchid=100012321")
   if err != nil {
      // Process error
   }
   log.Printf("status=%d resp=%s", result.Response.StatusCode, result.Response.Body)
}


// Call Query All Refund API
public function queryAllRefund($instance){
    try {
        $resp = $instance
            ->v3->global->refunds
            ->get([
                'query' => [
                    'out_trade_no' => 'YX001',
                    'count' => 10,
                    'offset' => 0,
                    'sp_mchid' => '1900000000',
                    'sub_mchid'=> '100012321'
                ]
            ]);

        echo $resp->getStatusCode(), PHP_EOL;
        echo $resp->getBody(), PHP_EOL;
    } catch (Exception $e) {
        // Exception handling
    }
}


									{
										"stock_id": "Python",
										"stock_creator_mchid": "123456",
										"limit": 10,
									}

Critical parameters:

out_trade_no: Internal order ID in merchant’s system

transaction_id: WeChat order ID

offset: Start position of paging

count: Number of records returned in a single page, up to 20 records.

Please refer to the API document for ordering by scanning code for other critical parameters.

3.2.7 Download statement of account

Procedure: Merchants can download the historical transaction statements by calling this interface on a daily basis, and correct the payment information by reconciling the statements.

Code example

JAVA Go PHP


    @Test
    //Downloading Reconciliation API
    public void downloadReconTest() throws IOException {
        HttpGet httpGet = new HttpGet("https://apihk.mch.weixin.qq.com/v3/global/statements?date=20220401&mchid=1900000000");
        httpGet.addHeader("Accept", "application/json");
        httpGet.addHeader("Content-type", "application/json; charset=utf-8");
        CloseableHttpResponse response = httpClient.execute(httpGet);
        //Process the response 
    }


//Download recon file API
func downloadReconFile() {
   result, err := client.Get(ctx, "https://apihk.mch.weixin.qq.com/v3/global/statements?date=20220401&mchid=1900000000")
   if err != nil {
      // Process error
   }
   log.Printf("status=%d resp=%s", result.Response.StatusCode, result.Response.Body)
}


//Downloading Reconciliation API
public function downloadReconFile($instance){
    try {
        $resp = $instance
            ->v3->global->statements
            ->get([
                'query' => [
                    'date' => '20220401',
                    'mchid' => '1900000000'
                ]
            ]);

        echo $resp->getStatusCode(), PHP_EOL;
        echo $resp->getBody(), PHP_EOL;
    } catch (Exception $e) {
        // Exception handling
    }
}


									{
										"stock_id": "Python",
										"stock_creator_mchid": "123456",
										"limit": 10,
									}

Critical parameters:

date: Statement date, format: 20180103

Please refer to the API document for ordering by scanning code for other critical parameters.

3.2.8 Close and order

Procedure: After placing an order, call this interface to close the orders not paid, allowing the merchant replace the order ID to re-order and initiate payment or avoid repeated payment by the user after quiting merchant's system without accepting the order.

Code example

JAVA Go PHP


    @Test
    //Call close order API
    public void closeOrderTest() throws IOException {
		String closeBody = String.join("\n" ,
                		"{" ,
                        "    'sp_mchid': '10000100'," ,
                        "    'sub_mchid': '20000100'" ,
                        "}").replace("'","\"");
        HttpPost httpPost = new HttpPost("https://apihk.mch.weixin.qq.com/v3/global/transactions/out-trade-no/YX001/close");
        httpPost.addHeader("Accept", "application/json");
        httpPost.addHeader("Content-type", "application/json; charset=utf-8");
        httpPost.setEntity(new StringEntity(closeBody));
        CloseableHttpResponse response = httpClient.execute(httpPost);
        System.out.println(response.getStatusLine().getStatusCode());
    }


//Call close order API
func closeOrder() {
   closeOrderBody := `{
    "sp_mchid": "10000100",
    "sub_mchid": "20000100"
   }`
   result, err := client.Post(ctx, "https://apihk.mch.weixin.qq.com/v3/global/transactions/out-trade-no/YX001/close", closeOrderBody)
   if err != nil {
      // Process error
   }
   log.Printf("status=%d resp=%s", result.Response.StatusCode, result.Response.Body)
}


// Call close order API
public function closeOrder($instance){
    try {
        $resp = $instance
            ->v3->global->transactions->outTradeNo->_out_trade_no_->close
            ->post([
                'json' => [
                'sp_mchid'     => '10000100',
                'sub_mchid'    => '20000100'
                ],
                'out_trade_no' => 'YX0001'
            ]);
        echo $resp->getStatusCode(), PHP_EOL;
        echo $resp->getBody(), PHP_EOL;
    } catch (Exception $e) {
        // Exception handling
    }
}


									{
										"stock_id": "Python",
										"stock_creator_mchid": "123456",
										"limit": 10,
									}

Critical parameters:

out_trade_no: Internal order ID in merchant’s system

transaction_id: WeChat order ID

Please refer to the API document for ordering by scanning code for other critical parameters.

3.2.9 Download platform certificate

Procedure: Before calling other interfaces, call this interface to download the platform certificate to verify the signature of the returned message and decrypt the encrypted fields therein.

Code example

JAVA Go PHP


    @Test
    //Call certificate downloading API
    public void certDownloadingTest() throws IOException {
        HttpGet httpGet = new HttpGet("https://apihk.mch.weixin.qq.com/v3/global/certificates");
        httpGet.addHeader("Accept", "application/json");
        httpGet.addHeader("Content-type", "application/json; charset=utf-8");

        CloseableHttpResponse response = httpClient.execute(httpGet);
        //Process the response 
//Get the response body: EntityUtils.toString(response.getEntity());
//Get the response status code: response.getStatusLine().getStatusCode();

        //Instead of calling the API to download platform certificate，
        //We also recommend use the certificateMenager to get the valid certificate
        verifier.getValidCertificate();
    }


//Calling download certificate API
func downloadCert() {
   result, err := client.Get((ctx, "https://apihk.mch.weixin.qq.com/v3/global/certificates"))
   if err != nil {
      if core.IsAPIError(err, "INVALID_REQUEST") {
         //Process invalid request
      }
      // Process other error
   }
   log.Printf("status=%d resp=%s", result.Response.StatusCode, result.Response.Body)
}


// Call download certificate API
public function downloadCert($instance){
    $resp = $instance->chain('v3/global/certificates')->get(
        ['debug' => true] // debug mode，https://docs.guzzlephp.org/en/stable/request-options.html#debug
    );
    echo $resp->getBody(), PHP_EOL;
}


									{
										"stock_id": "Python",
										"stock_creator_mchid": "123456",
										"limit": 10,
									}

Critical parameters: None

Please refer to the API document for ordering by scanning code for other critical parameters.

3.2.10 Notification of payment results

Procedure: After the user makes the payment, WeChat Pay will push the payment result notification to the notify_url introduced while placing the order, and the merchant needs to feed back accordingly after receiving the notification.

Notes:

• The same notification may be sent to the merchant system multiple times. The merchant system must be able to process duplicate notifications properly. It is recommended to first check the status of the corresponding business data when receiving a notification for processing, and determine whether the notification has been processed. If it has not been processed, the notification should be processed once again; if it has been processed, the success result should be returned. Before status checking and processing of the business data, a data lock should be used to implement concurrency control and avoid data confusion caused by function reentry.

• If no callback is received from WeChat side after all notification frequencies (4 hours), the merchant shall call the Query Order interface to confirm the order status.

Special reminder: The merchant system must perform signature verification for the content of the notification of payment results, and verify whether the returned order amount is consistent with that of the merchant side, thus preventing any "false notifications" and even loss of funds caused by data leakage.

3.2.10.1 Notification Rules

After the payment is made, WeChat will send the related payment result and user information to the merchant. The merchant needs to receive and process the information, and return the response successfully. Only the successful payments will be notified.

When interacting with the background notification, if the response received by WeChat from the merchant is not success or timed out, WeChat thinks the notification fails. WeChat will periodically resend the notification according to the specified policy to maximize the success rate of the notification, but WeChat does not guarantee final success of the notification. ((Notification frequency is 15s/15s/30s/3m/10m/20m/30m/30m/30m/60m/3h/3h/3h/6h/6h - total 24h and 4m)) for repeated notification.

3.2.10.2 Notification Message

The payment result notification accesses the notification URL set by the merchant using the POST method, and the notification data is transmitted through the request body (BODY) in the JSON format. The data in the notification includes the encrypted payment result details.

The certificate decryption process is detailed as follows

1、Obtain the merchant's key from the merchant platform, and record it as “key”.

2、Get the corresponding parameters “nonce” and “associated_data” for the algorithm described in “algorithm” (currently AEAD_AES_256_GCM).

3、Decrypt “ciphertext” with “key”, “nonce” and “associated_data” (decode base64 for ciphertext first, and then decrypt it) to obtain the certificate content

Notes:

For the interface details of the AEAD_AES_256_GCM algorithm, please refer to rfc5116. The length of the key used in Wechat Pay is 32 bytes, the length of the random string nonce is 12 bytes, and the length of associated_data is less than 16 bytes and may be empty.

3.2.10.3 Notification Signature

Encryption does not guarantee that the notification requests come from WeChat. WeChat will sign the notification sent to the merchant and put the signature value in the HTTP header Wechatpay-Signature of the notification. Merchants should verify the signature to confirm that the request comes from WeChat, and not any other third parties. For the signature verification algorithm, please refer to WeChat Pay API V3 Signature Verification.

3.2.10.4 Callback Example

Notification of Successful Payments


{
    "id":"EV-2018022511223320873",
    "create_time":"20180225112233",
    "resource_type":"encrypt-resource",
    "event_type":"TRANSACTION.SUCCESS",
    "resource" : {
        "algorithm":"AEAD_AES_256_GCM",
        "ciphertext": "...",
        "nonce": "...",
        "associated_data": ""
    }
}

An example of the resource object obtained after the merchant decrypts the resource object


{
    "id": "1008450740201411110005820873",
    "sp_appid": "wx2421b1c4370ec43b",
    "sp_mchid": "10000100",
    "sub_mchid": "20000100",
    "out_trade_no": "20150806125346",
    "payer": {
      "sp_openid": "oUpF8uN95-Ptaags6E_roPHg7AG0"
    },
    "amount" : {
        "total": 528800,
        "currency": "HKD",
        "payer_total": 518799,
        "payer_currency": "CNY",
        "exchange_rate" : {
            "type": "SETTLEMENT_RATE",
            "rate": 8000000
        }
    },
    "trade_type": "MICROPAY",
    "trade_state": "SUCCESS",
    "trade_state_desc": "支付成功",
    "bank_type": "CCB_DEBIT",
    "attach": "支付测试",
    "success_time": "2018-06-08T10:34:56+08:00",
    "promotion_detail":[
        {
            "promotion_id":"109519",
            "name":"单品惠-6",
            "scope":"SINGLE",
            "type":"DISCOUNT",
            "amount":1,
            "currency":"HKD",
            "activity_id":"931386",
            "wechatpay_contribute_amount":1,
            "merchant_contribute_amount":0,
            "other_contribute_amount":0,
            "goods_detail":[
                {
                    "goods_id":"iphone6s_16G",
                    "goods_remark":"商品备注",
                    "quantity":1,
                    "price":528800
                }
            ]
        }
    ]
}

3.2.10.5 Notification Response

The http response code of the payment notification should be either 200 or 204 for normal receipt. In case of any callback processing error, the HTTP status code of the response should be 500 or 4xx.

Notes:

When the merchant background returns the failure response to Weixin Pay, Weixin Pay will record the response message. It is recommended that the merchant return the message in the following format.

Please refer to the API document for ordering by scanning code for other critical parameters.

3.2.11 Refund notification

Notes:

• The same notification may be sent to the merchant system multiple times. The merchant system must be able to process duplicate notifications properly. It is recommended to first check the status of the corresponding business data when receiving a notification for processing, and determine whether the notification has been processed. If not, the notification should be processed; if it has been processed, the success result should be returned. Before status checking and processing of the business data, a data lock should be used to implement concurrency control and avoid data confusion caused by function reentry.

• If no callback is received from WeChat side after all notification frequencies (4 hours), the merchant shall call the Query Order interface to confirm the order status.

Special reminder: The merchant system must perform signature verification for the content of the notification of payment results, and verify whether the returned order amount is consistent with that of the merchant side, thus preventing any "false notification" and even capital loss caused by data leakage.

3.2.11.1 Notification Rules

In case of any refund status changes, WeChat will send the related refund results to the merchant.

3.2.11.2 Notification Message

The deduction result notification accesses the notification URL set by the merchant using the POST method, and the notification data is transmitted through the request body (BODY) in the JSON format. The data in the notification includes the details about the encrypted refund result.

The certificate decryption process is detailed as follows

1、Obtain the merchant's key from the merchant platform, and record it as “key”.

2、Get the corresponding parameters “nonce” and “associated_data” for the algorithm described in “algorithm” (currently AEAD_AES_256_GCM).

3、Decrypt “ciphertext” with “key”, “nonce” and “associated_data” (perfomr base64 decoding for ciphertext first, and then decrypt it) to obtain the certificate content

Notice

For the interface details of the AEAD_AES_256_GCM algorithm, please refer to rfc5116. The length of the key used in Wechat Pay is 32 bytes, the length of the random string nonce is 12 bytes, and the length of associated_data is less than 16 bytes and may be empty.

3.2.11.3 Notification Signature

3.2.11.4 Callback Example

Notification of Refund Result


{
	"id": "EV-2018022511223320873",
	"create_time": "2018-06-08T10:34:56+08:00",
	"resource_type": "encrypt-resource",
	"event_type": "REFUND.SUCCESS",
	"summary": "退款成功",
	"resource": {
		"original_type": "refund",
		"algorithm": "AEAD_AES_256_GCM",
		"ciphertext": "...",
		"associated_data": "",
		"nonce": "..."
	}
}

An example of the resource object obtained after the merchant decrypts the resource object


{
    "sp_mchid": "1900000100",
    "sub_mchid": "1900000109",
    "transaction_id": "1008450740201411110005820873",
    "out_trade_no": "20150806125346",
    "refund_id": "50200207182018070300011301001",
    "out_refund_no": "7752501201407033233368018",
    "refund_status": "SUCCESS",
    "success_time": "2018-06-08T10:34:56+08:00",
    "recv_account": "招商银行信用卡0403",
    "fund_source": "REFUND_SOURCE_UNSETTLED_FUNDS",
    "amount" : {
        "total": 528800,
        "currency": "HKD",
        "refund": 528800,
        "payer_total": 528800,
        "payer_refund": 528800,
        "payer_currency": "HKD",
        "exchange_rate" : {
            "type": "SETTLEMENT_RATE",
            "rate": 100000000
        }
    }
}

3.2.11.5 Notification Response

The http response code of the refund notification should be either 200 or 204 for normal receipt. In case of any callback processing error, the HTTP status code of the response should be 500 or 4xx.

Note:

When the merchant background returns the failure response to Weixin Pay, Weixin Pay will record the response message. It is recommended that the merchant return the message in the following format.

Please refer to the API document for ordering by scanning code for other critical parameters.

3.2.12 API for querying fund settlement details

Procedure: After transactions are completed, the merchant can query the settled fund details (sette_state is SETTLED) or the unsettled fund details (sette_state is UNSETTLE) by settlement date.

Note:

This API is designed for the cross-border acquiring institutions/direct merchants. In particular, if institutions/merchants in Japan and Macao have enabled Hong Kong Wallet services, they need to connect this API.

Code example

JAVA Go PHP


    @Test
    //Query Settlement API
    public void querySettlementTest() throws IOException {
        HttpGet httpGet = new HttpGet("https://apihk.mch.weixin.qq.com/v3/global/settle/settlements" +
                "?sub_mchid=100012321&settle_state=SETTLED&settle_start_date=20221225" +
                "&settle_end_date=20221226&offset=10&limit=5");
        httpGet.addHeader("Accept", "application/json");
        httpGet.addHeader("Content-type", "application/json; charset=utf-8");
        CloseableHttpResponse response = httpClient.execute(httpGet);
        //Process the response 
    }


//Query settlement API
func querySettlement() {
   result, err := client.Get(ctx, "https://apihk.mch.weixin.qq.com/v3/global/settle/settlements?sub_mchid=100012321&settle_state=SETTLED&settle_start_date=20221225&settle_end_date=20221226&offset=10&limit=5")
   if err != nil {
      // Process error
   }
   log.Printf("status=%d resp=%s", result.Response.StatusCode, result.Response.Body)
}


//Querying Settlement Info API
public function querySettlementInfo($instance){
    try {
        $resp = $instance
            ->v3->global->settle->settlements
            ->get(['query' => [
                'sub_mchid' => '100012321',
                'settle_state' => 'SETTLED',
                'settle_start_date' => '20221225',
                'settle_end_date' => '20221226',
                'offset' => '10',
                'limit' => '5'
            ]]);

        echo $resp->getStatusCode(), PHP_EOL;
        echo $resp->getBody(), PHP_EOL;
    } catch (\Exception $e) {
        // Exception handling
    }
}


									{
										"stock_id": "Python",
										"stock_creator_mchid": "123456",
										"limit": 10,
									}

Critical parameters:

settle_state： Fund settlement status, enumeration value:

SETTLED：settled

UNSETTLE：not settled

Please refer to the API document for ordering by scanning code for other critical parameters.

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Payments

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Development Guidelines

1. API Rules

2. Development Environment Setup

2.1.1. Conditions of Use

2.1.2. Installation

2.1.3. Initialization

2.1.4. General Functions

2.2.1. Conditions of Use

2.2.2. Installation

2.2.3. Initialization

2.2.4. General Functions

2.3.1. Conditions of Use

2.3.2. Installation

2.3.3. Initialization

2.3.4. General Functions

2.4. Key Points of iOS Development

I. OpenSDK Upgrade Guidelines for iOS

II. Development Configuration:

I. Background Settings

II. Register APPID

3. Fast Access

3.1. Business Sequence Chart

3.2. Example of API access

3.2.1 Place an order

3.2.2 APP Pull-up Payment

3.2.3 Query

3.2.4 Refund

3.2.5 Query one refund

3.2.6 Query all refunds

3.2.7 Download statement of account

3.2.8 Close and order

3.2.9 Download platform certificate

3.2.10 Notification of payment results

3.2.10.1 Notification Rules

3.2.10.2 Notification Message

3.2.10.3 Notification Signature

3.2.10.4 Callback Example

3.2.10.5 Notification Response

3.2.11 Refund notification

3.2.11.1 Notification Rules

3.2.11.2 Notification Message

3.2.11.3 Notification Signature

3.2.11.4 Callback Example

3.2.11.5 Notification Response

3.2.12 API for querying fund settlement details