An article explaining in detail how to implement WeChat cash withdrawal function in PHP

With the development of social software, WeChat has become an indispensable part of people's daily life. As a result, WeChat Pay has become more and more popular, and many applications and services based on WeChat Pay have emerged.

In these applications and services, the cash withdrawal function has become an indispensable part. So, how to implement WeChat withdrawal function in PHP? This article will introduce you to the specific implementation method.

1. Development environment

Before starting development, you need to know some necessary information. First, you need a WeChat merchant account and key, which you can apply for on the WeChat payment official website. Additionally, you need to install a PHP development environment and use the curl PHP extension. After installing these, you're ready to get started.

2. Code implementation

1. Prepare parameters

Obviously, you need to prepare some necessary parameters for the withdrawal request. This mainly refers to information such as merchant number, key, withdrawal amount, withdrawal name, withdrawal account and remarks.

2. Generate signature

Each WeChat payment interface requires signature verification. Before generating a signature, you need to prepare an array containing all parameters and keys. The steps to generate a signature are as follows:

• Sort the array in ascending order by key
• Use the URL key-value pair format to splice them together
• Add at the end of this string Merchant’s payment secret key
• Encrypt this string with MD5
• Convert the MD5 value to uppercase

The code to generate the signature is as follows:

function generateSign($params, $key) {
    ksort($params);
    $string = "";
    foreach ($params as $k => $v) {
        if (!empty($v) && $k != "sign") {
            $string .= "$k=$v&";
        }
    }

    $string .= "key=$key";
    $string = md5($string);
    $result = strtoupper($string);
    return $result;
}

3. Send a request

After constructing the request parameters and signature, you can send a withdrawal request through the curl library. Generally speaking, the URL of the WeChat payment withdrawal interface is:

https://api.mch.weixin.qq.com/mmpaymkttransfers/promotion/transfers

The code to send the request is as follows:

function sendWithdrawRequest($params) {
    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL, "https://api.mch.weixin.qq.com/mmpaymkttransfers/promotion/transfers");
    curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
    curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, false);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    curl_setopt($ch, CURLOPT_POST, 1);
    curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($params));
    $data = curl_exec($ch);
    curl_close($ch);
    return $data;
}

4. Processing the response

When the WeChat payment server After receiving the withdrawal request, a response in XML format will be returned. You need to process this response to understand the withdrawal results. The following is a sample code for processing responses:

function processWithdrawResponse($xml) {
    $array = json_decode(json_encode(simplexml_load_string($xml, 'SimpleXMLElement', LIBXML_NOCDATA)), true);
    return $array;
}

3. Notes

During development, there are some things that need to be paid attention to. First, you must ensure that the merchant number and key are correct. Secondly, you must ensure that the withdrawal amount is within the limit of WeChat Pay. Finally, you need to pay special attention to the error code returned when an error occurs so that it can be handled in a timely manner.

4. Summary

This article introduces how to implement the WeChat cash withdrawal function in PHP. First, you need to prepare the necessary development environment and parameters, then generate signatures, send requests, process responses, and pay attention to some matters that need attention during development.

As an excellent web development language, PHP can be used in combination with WeChat Pay to improve the user's payment experience and also facilitate merchant management and cash withdrawals.

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