How to format error messages in Golang?

How to format error messages in Go? Use the fmt package to format error strings with the Sprintf and Errorf functions. Use the errors package to create and format errors, for example using the New and Wrap methods. In practice, web-based applications use formatted error messages to provide meaningful user information.

#How to format error messages in Go?

The error handling mechanism in Golang is very powerful and allows developers to create and handle custom errors. It is important to format error messages to provide meaningful error information to users or other developers.

Formatting errors using the fmt package

The easiest way to format error messages is to use the fmt package. The fmt package provides several functions, such as Sprintf and Errorf, which can be used to format strings.

package main

import (
    "fmt"
    "log"
)

func main() {
    // 使用 Sprintf 格式化错误字符串。
    err := fmt.Errorf("读取文件时出错：%s", "test.txt")
    log.Fatal(err)
}

Format errors using the errors package

errors The package provides higher-level functions for creating and formatting errors. It contains methods such as New and Wrap that return well-formed error values.

package main

import (
    "errors"
    "log"
)

func main() {
    // 使用 New 创建一个错误值。
    err := errors.New("读取文件时出错")
    log.Fatal(err)
}

Practical case: Web-based error handling

In Web-based applications, formatted error messages are particularly important. Here is an example of a formatted web error message:

package main

import (
    "errors"
    "log"
    "net/http"
)

func main() {
    http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
        if err := readDataFromDB(); err != nil {
            // 格式化错误并以 JSON 响应返回。
            http.Error(w, fmt.Sprintf("数据读取失败：%s", err), 500)
        }
    })
}

func readDataFromDB() error {
    return errors.New("数据库连接失败")
}

Formatted error messages are an integral part of any Go application. By understanding how to use the fmt and errors packages, developers can effectively create and format error messages to provide meaningful information to users.

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