How to use context to implement request interceptor in Go

How to use context to implement request interceptor in Go

Introduction:
In the actual development process, we often need to intercept and process requests. For the Go language, you can use the context package to implement request interception and middleware processing. This article will introduce how to use the context package to implement a request interceptor and provide corresponding code examples.

1. What is context package?
The context package is a package in the Go language used to pass the context of the request. After a request is initiated, the context package can pass some request-related information, such as the deadline of the request, the intermediate results of the request, etc. At the same time, the context package can also implement functions such as request cancellation and timeout.

2. Use the context package to implement the request interceptor
In the Go language, you can use the context package to implement the request interceptor. Interceptors can be used to implement some common functions, such as permission verification, request logging, etc. Below we will use an example to demonstrate how to use the context package to implement a request interceptor.

First, we create an intercepted function handleRequest, which is used to process the user's request:

func handleRequest(ctx context.Context) {
    // 处理请求
    fmt.Println("处理请求")
}

Next, we create an interceptor function interceptor, which is used to intercept the request , and do some additional processing before request processing:

func interceptor(ctx context.Context) context.Context {
    // 在请求处理之前执行拦截器的逻辑
    fmt.Println("执行拦截器逻辑")
    
    // 返回新的上下文
    newContext := context.WithValue(ctx, "token", "123456")
    return newContext
}

In the above code, we first print the message that executes the interceptor logic, and pass a value named "token" through the WithValue method of the context package is added to the context and the new context is returned as the return value.

Next, we can call the interceptor function to intercept the request of the handleRequest function:

func main() {
    // 创建一个空白的上下文
    ctx := context.Background()
    
    // 调用interceptor函数来拦截handleRequest函数的请求
    newCtx := interceptor(ctx)
    
    // 调用handleRequest函数来处理请求
    handleRequest(newCtx)
}

In the above code, we first create a blank context object ctx, and use the interceptor function to intercept the request. The context object intercepts and generates a new context object newCtx. Then, we pass newCtx as a parameter to the handleRequest function to handle the request.

Finally, we can run the above code to see the effect. It can be found that before calling the handleRequest function, we will first print the message that executes the interceptor logic.

3. Conclusion
By using the context package, it becomes very simple to implement a request interceptor in the Go language. We can define an interceptor function and perform some additional processing on the request. In this way, we can implement some common functions, such as permission verification, request logging, etc.

The above is the entire content of this article. I hope it will be helpful for everyone to understand how to use the context package to implement a request interceptor. Thanks for reading!

Reference:

• Go Documentation: https://golang.org/pkg/context/

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