How to use PHP to implement printing operations in WeChat applet

With the popularity of WeChat mini programs, more and more merchants are beginning to use WeChat mini programs to manage and promote their businesses, including the need to print receipts. In the WeChat applet, PHP language is required to implement printing operations. This article will introduce how to use PHP to implement printing operations in WeChat mini programs.

1. Understand the printing process of the WeChat applet

Before introducing how to use PHP to implement the printing operation in the WeChat applet, let's first understand the printing process of the WeChat applet. In the WeChat applet, the printing operation is divided into two parts: the applet side and the server side. The specific process is as follows:

1. Mini program:

(1) The user enters the information that needs to be printed in the mini program.

(2) The applet sends the input information to the server through the network.

2. Server side:

(1) Receive the printing information sent by the applet.

(2) Convert the received printing information into instructions that need to be recognized by the printing device, and then send them to the printing device through the network.

(3) The device will start printing after receiving the instruction.

2. Use PHP to implement WeChat applet printing

Before using PHP to implement WeChat applet printing, one problem needs to be clarified, that is, the server needs to implement network programming to receive the information sent by the applet. Print information and send instructions to the printing device. Therefore, you need to use PHP's network programming library to implement this function.

1. Preparation work

Before using PHP to implement WeChat applet printing, you need to prepare two important tools, one is server equipment and software, and the other is the applet Backend code.

Server equipment and software need to be equipped with a printing library and HTTP server. It is recommended to use Raspberry Pi 4 and CUPS. CUPS is a comprehensive printing system that can be used directly with Raspberry Pi 4. At the same time, you can use Apache or Nginx as the HTTP server.

The back-end code of the mini program can be written in PHP. It is recommended to use the PHP framework Laravel here. Laravel is an excellent PHP framework that enables rapid development of web applications. In this article, we will use Laravel to develop the backend code.

2. Implement printing operation

The following describes how to use PHP to implement printing operation of WeChat applet. The specific steps are as follows:

(1) Write Laravel routing

In Laravel, we need to write routing to process the printing information sent by the applet. Open the routes/web.php file and add the following code:

Route::post('/print', 'PrintController@print');

This code indicates that a POST request is created , the corresponding processing function is the print function of PrintController.

(2) Writing PrintController controller

In Laravel, a controller usually contains functions that handle requests, that is, operations, which will be associated with specific routing URLs. In this example, we create a controller called PrintController to handle print requests. Open the app/Http/Controllers/PrintController.php file and add the following code:

namespace AppHttpControllers;

use IlluminateHttpRequest;

class PrintController extends Controller
{

public function print(Request $request)
{
    // 获取打印信息
    $text = $request->input('text');

    // 编码打印机指令
    $encode = 'TEC-IT B-PAC 3.2 Barcode ActiveX';

    // 发送打印指令到CUPS服务器
    exec("lp -d printername -o raw /dev/stdin <<< `{$encode}`");
}

}

This code implements the print function, which is used to process print requests. In the function, first obtain the printing information sent by the applet, then encode the printer instructions and send them to the CUPS server.

(3) The applet sends a print request

In the applet, you can create a print command button and bind it to a function. When the user clicks the print command, the applet will send a POST request to the server and pass the information to be printed as parameters. For example:

wx.request({

url: 'http://your-server/print',
data: { text: 'This is a test print.' },
method: 'POST',
success: function (res) {
    console.log(res);
}

});

This code means sending a POST request to the server and passing the print information as data. On the server side, the PrintController controller's print function will use the lp command to send the print command to the printing device.

3. Summary

This article introduces how to use PHP to implement printing operations in WeChat applet. Through the introduction of this article, you have already understood the WeChat applet printing process and how to use the PHP framework Laravel to write server-side code to implement the printing function. Hope this article can help you.

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