golang error code

Golang is a relatively new programming language, but over the past few years it has developed into a highly regarded high-level programming language due to its simplicity, efficiency, and ease of learning. Error handling is an inevitable part of writing Golang code. This article will explore the error handling mechanism and common error codes in Golang.

Error handling in Golang

The error handling mechanism in Golang mainly depends on the error type. A function can return a value of type error, and this value will be passed to the place where the function is called. , which can check whether the value is nil. If it is not nil, it means that the function returned an error, and the caller must handle this error and perform appropriate operations. If nil, it means the function executed successfully.

Here is a simple example that demonstrates how to return an error in Golang:

func divide(a, b float64) (float64, error) {
    if b == 0 {
        return 0, errors.New("division by zero")
    }
    return a / b, nil
}

func main() {
    result, err := divide(6, 0)
    if err != nil {
        fmt.Println("Error:", err)
        return
    }
    fmt.Println(result)
}

In the above example, the divide function checks whether the denominator is 0. If 0, a new error type value containing the error message "division by zero" is returned. In the main function, we check if the returned error value is nil and print an error message if not.

Error code

In addition to the error type, there is also an error handling mechanism in Golang, namely error code. The error code is an integer value that identifies different types of errors. Typically, these error codes are defined in package-level variables and shared among multiple functions.

The following is an example that demonstrates a function that uses error codes:

var (
    ErrBadRequest  = errors.New("bad request")
    ErrUnauthorized = errors.New("unauthorized")
)

func getUser(userId int) (user, int, error) {
    if userId <= 0 {
        return user{}, 0, ErrBadRequest
    } else if userId == 123 {
        return user{name: "Alice", age: 30}, 200, nil
    }
    return user{}, 0, ErrUnauthorized
}

func main() {
    user, status, err := getUser(123)
    if err != nil {
        if err == ErrBadRequest {
            fmt.Println("Error:", err)
            // 返回 400 所代表的错误码
            return
        } else if err == ErrUnauthorized {
            fmt.Println("Error:", err)
            // 返回 401 所代表的错误码
            return
        }
    }
    fmt.Println("User:", user)
    fmt.Println("Status:", status)
}

In this example, we define two error codes: ErrBadRequest and ErrUnauthorized. In the getUser function, if the passed user ID is less than or equal to 0, ErrBadRequest is returned; if the user ID is equal to 123, the user structure, status code 200 and nil are returned, indicating success; otherwise, ErrUnauthorized is returned.

In the main function, we check the value of error type. We return HTTP error code 400 if the error is ErrBadRequest and 401 if the error is ErrUnauthorized. Otherwise, we print information about the user and status code.

Summary

The error handling mechanism in Golang allows developers to easily identify errors and exceptions in handler functions. The error type is the core of error handling in Golang. It provides basic error information and handling methods. The error code mechanism provides a more flexible error handling method and can define different error codes for different error types. The error code mechanism can provide a more elegant solution when dealing with a large number of errors. Whether you use error codes or error objects, you should choose the appropriate error handling mechanism based on business needs.

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