What should I do if the uniapp subcomponent cannot request the interface?

1. Introduction

During the development process, we often use the uni-app framework to quickly develop small programs, Apps and H5 applications. Among them, an important feature of uni-app is the use of vue.js components and syntax, and it also supports multi-terminal packaging of mini programs and apps.

However, in actual use, we may encounter various problems. For example, when we use sub-components in uni-app, we may encounter the problem that the sub-components cannot request the interface.

Today, we will discuss this problem and possible solutions.

2. Why can't the uni-app subcomponent request the interface?

When using uni-app to develop applets, Apps and H5 applications, we usually use components to implement various functions.

And communication between components is a complex issue. In uni-app, we can use props between parent and child components to pass data, or use the global event bus eventHub provided by uni-app to implement communication between components.

However, when we initiate a request in a subcomponent, an error of "request failed" or "interface call failed" will often appear. This is because, in the uni-app development mode, requests in subcomponents are cross-domain requests by default, while cross-domain requests are not allowed in mini programs. Therefore, we need to do some processing on the request to support requesting the interface in the uni-app subcomponent.

3. Solution

3.1. Solve the cross-domain request problem

As mentioned above, requests in the uni-app subcomponent are cross-domain requests by default . Therefore, we need to handle cross-domain requests accordingly.

We can modify the request interceptor of uni-app in the project's main.js file or App.vue file to implement cross-domain requests.

The specific method is to modify the requested protocol, domain name and port before requesting, as shown below:

uni.request({
    url: 'https://www.example.com/api/getData',
    method: 'POST',
    header: {
        'Content-Type': 'application/json'
    },
    // 这里替换成你的自定义拦截器
    beforeSend: function(request) {
        request.url = '/proxy' + request.url;
    },
    success: function(res) {
        console.log(JSON.stringify(res));
    },
    fail: function(err) {console.log(err)}
});

In the above code, we modify the request address before requesting. Added a "/proxy" prefix. In this way, the request will be intercepted and entered into the proxy server. The proxy server forwards the request to the target server and returns the response from the target server. Finally, we can obtain the server's data and solve the cross-domain request problem.

It should be noted that we need to configure cross-domain requests on the server side, otherwise the proxy server will still be unable to access the target server. This can be configured by referring to the relevant documentation.

3.2. Request interface in sub-component

After solving the cross-domain request problem, we can initiate requests in the sub-component of uni-app.

The specific method is to use the uni.request method to initiate a request in the JS file of the subcomponent, as shown below:

uni.request({
    url: 'https://www.example.com/api/getData',
    method: 'POST',
    header: {
        'Content-Type': 'application/json'
    },
    data: {
        // 这里可以传递一些参数
        name: 'demo'
    },
    success: function(res) {
        console.log(JSON.stringify(res));
    },
    fail: function(err) {console.log(err)}
});

When the request is successful, we can get the return through the success function The data.

4. Summary

This article introduces the problem that the uni-app subcomponent cannot request the interface, and provides a solution.

It should be noted that we need to solve the cross-domain request problem before making the request. At the same time, when requesting data, we need to pay attention to the settings of some main parameters, such as the requested address, the requested method, the requested header, the requested data, etc.

In actual development, we can make appropriate adjustments and optimizations according to different scenarios to achieve better user experience and development efficiency.

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