How to make public data available for all controllers in the Go Gin framework?

How all controllers share common data in the Go Gin framework

In the web development of the Go Gin framework, efficient access to public data is crucial. Unlike PHP's inheritance mechanism, Go Gin needs to adopt other strategies. This article will explore two methods: global sharing of data and request sharing of data.

Method 1: Globally shared data (suitable for database configuration, site information, etc.)

For public data that remains unchanged throughout the application life cycle, such as database connection information, site names, etc., the most direct way is to use global variables. However, this needs to be handled with caution to avoid concurrency problems and reduced code maintenance. It is recommended to use configuration packages to manage these global data, such as viper or similar libraries.

Method 2: Shared data within the request (applicable to user identity information, request context, etc.)

Gin's middleware mechanism is ideal for data shared within a single request, such as user information, the language settings of the current request, etc. The middleware can set this data into context at an early stage of the request processing chain and then access it in subsequent controllers.

The following example shows how to set up and get public data in Gin using middleware:

 package main

import (
    "github.com/gin-gonic/gin"
    "net/http"
)

func main() {
    router := gin.Default()

    // Middleware: Set public data router.Use(func(c *gin.Context) {
        c.Set("user_id", 123) // Example: User ID
        c.Set("request_time", "2024-10-27 10:00:00") // Example: Request time c.Next()
    })

    // Controller: Get and use public data router.GET("/test", func(c *gin.Context) {
        userID, _ := c.Get("user_id")
        requestTime, _ := c.Get("request_time")
        c.JSON(http.StatusOK, gin.H{
            "user_id": userID,
            "request_time": requestTime,
            "message": "Data accessed successfully!",
        })
    })

    router.Run(":8080")
}

In this example, the middleware sets two key-value pairs user_id and request_time to context . The controller of /test route gets these values ​​through c.Get() method. All routes using this middleware can access this data.

Which method to choose depends on the life cycle and scope of the data. For global data, using configuration packages is safer and more reliable; for in-request data, Gin middleware is the best practice. Using these two methods reasonably can effectively manage and access public data in the Go Gin framework, improving the readability and maintainability of the code.

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