How to Pass Additional Arguments to Handler Functions in Gorilla Mux?

Handling Handler Arguments with Gorilla Mux

In Gorilla Mux, by default, handlers receive only http.ResponseWriter and *http.Request. However, there are scenarios where passing additional arguments to handlers is necessary, such as a database connection object.

Approach 1: Handler as a Method of a Custom Type

One way to achieve this is to define a custom type that holds the additional data and implements the http.HandlerFunc interface.

type UserHandler struct {
    db *gorm.DB
}

func (h UserHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
    // here you can use db
}

// usage:
db := createDB()
users := UserHandler{db: db}
router.HandleFunc("/users/{id}", users.ServeHTTP)

Approach 2: Closure Function

Another option is to use a closure function to wrap the actual handler and inject the additional argument.

func showUserHandler(db *gorm.DB) http.HandlerFunc {
    return func(w http.ResponseWriter, r *http.Request) {
        // here you can use db
    }
}

// usage:
db := createDB()
router.HandleFunc("/users/{id}", showUserHandler(db))

Approach 3: Global Variables

In certain scenarios, using global variables may be acceptable, especially for shared resources like database connections. However, it's important to use them sparingly and understand the potential drawbacks.

var db *gorm.DB = createDB()

func showUserHandler(w http.ResponseWriter, r *http.Request) {
    // here you can use db
}

// usage:
router.HandleFunc("/users/{id}", showUserHandler)

Tips

• It's generally not recommended to use a global variable for the database object, as it can lead to concurrency issues.
• The best approach depends on your specific requirements.
• For a single database object, the closure function or handler method approach is more appropriate.
• For multiple instances or more complex dependencies, consider creating a custom context type that can be passed through the handlers.

The above is the detailed content of How to Pass Additional Arguments to Handler Functions in Gorilla Mux?. For more information, please follow other related articles on the PHP Chinese website!