WeChat Pay

API Intro

Request URL: The link is set through the notify_url parameter submitted in [Deduction to Place Order]. If the link cannot be accessed, the merchant will not receive the notification from WeChat. The address must be an HTTPS protocol address. If the link cannot be accessed, the merchant will not receive the notification from WeChat. The notification URL must be a URL that is directly accessible and cannot carry parameters. Example: notify_url: “http://pay.weixin.qq.com/wxpay/pay.action"

Request method: POST

Applicable object:Common modeInstitutional mode

API Rules: https://wechatpay-api.gitbook.io/wechatpay-api-v3

Notification Rules

After the deduction, WeChat will send the relevant payment result and user information to the merchant in the form of data stream. The merchant needs to receive and process the information, and return the response according to the document specifications. The notification result data will be encrypted to ensure security. The merchant needs to decrypt the notification data before getting the result data.

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. (The notification frequency is 15/15/30/180/1800/1800/1800/1800/3600 seconds.)

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 payment result.

The procedure of how to decrypt the notification data is described as follows.

1、Obtain the merchant's notification key from the merchant platform and record it as key.

2、5.Get the corresponding parameters nonce and associated_ data for the algorithm described in resource.algorithm (currently AEAD_AES_256_GCM).

3、6.Use key, nonce, and associated_data to decrypt the data ciphertext resource.ciphertext and get the resource object in the JSON form.

Note: For the information on the API of the algorithm `AEAD_AES_256_GCM`, see rfc5116. The length of the `key` used for WeChat Pay is 32 bytes, the length of the random string `nonce` is 12 bytes, and the length of the `associated_data` is less than 16 bytes or may be zero.

Request Parameters

Notification Signature

Encryption does not guarantee that the notification request comes from wechat pay. Wechat pay will sign the notification sent to the merchant and put the signature value in the Wechatpay-Signature of Notification's HTTP header. The merchant should verify the signature to confirm that the request is from wechat pay, not other third parties. For the algorithm of signature verification, please refer to 【Wechat Pay API V3 Signature Scheme】

Callback Example

Payment Success Result Notification

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

List of decrypted resource objects:

{
	"mchid": "10000100",
	"appid": "wx2421b1c4370ec43b",
	"out_trade_no": "20150806125346",
	"transaction_id": "1008450740201411110005820873",
	"attach": "支付测试",
	"trade_type": "AUTH",
	"bank_type": "CCB_DEBIT",
	"success_time": "2018-06-08T10:34:56+08:00",
	"trade_state": "SUCCESS",
	"trade_state_desc": "支付成功",
	"merchant_category_code": "1011",
	"contract_id": "Wx15463511252015071056489715",
	"payer": {
		"openid": "oUpF8uN95-Ptaags6E_roPHg7AG0"
	},
	"amount": {
		"total": 528800,
		"currency": "HKD",
		"payer_total": 518799,
		"payer_currency": "CNY",
		"exchange_rate": {
			"type": "SETTLEMENT_RATE",
			"rate": 8000000
		}
	},
	"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
		}]
	}]
}
                              

{
	"sp_mchid": "10000100",
	"sp_appid": "wx2421b1c4370ec43b",
	"sub_mchid": "20000100",
	"out_trade_no": "20150806125346",
	"transaction_id": "1008450740201411110005820873",
	"attach": "支付测试",
	"trade_type": "AUTH",
	"bank_type": "CCB_DEBIT",
	"success_time": "2018-06-08T10:34:56+08:00",
	"trade_state": "SUCCESS",
	"trade_state_desc": "支付成功",
	"merchant_category_code": "1011",
	"contract_id": "Wx15463511252015071056489715",
	"payer": {
		"sp_openid": "oUpF8uN95-Ptaags6E_roPHg7AG0"
	},
	"amount": {
		"total": 528800,
		"currency": "HKD",
		"payer_total": 518799,
		"payer_currency": "CNY",
		"exchange_rate": {
			"type": "SETTLEMENT_RATE",
			"rate": 8000000
		}
	},
	"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
		}]
	}]
}
                              

Payment Success Notification Parameters

Returned Result

After the merchant's backend has properly processed the notification, HTTP status code 200 or 204 needs to be returned. No specific content is required for 204.If other HTTP status codes are returned, WeChat Pay will deem the notification as a failure, and will send the notification regularly by following the aforesaid policies.

Note：If the merchant's backend fails to process a response, WeChat Pay will record the response message. It is recommended to return in the following format.

{
"code": "ERROR_NAME",
"message": "ERROR_DESCRIPTION",
}