Use golang's error wrapping and unwinding mechanism for error handling

Error handling in Go includes wrapping errors and unwinding errors. Wrapping errors allows one error type to be wrapped with another, providing a richer context for the error. Expand errors and traverse the nested error chain to find the lowest-level error for easy debugging. By combining these two technologies, error conditions can be effectively handled, providing richer error context and better debugging capabilities.

Use Go's error wrapping and unwinding mechanism for error handling

In Go, error handling is crucial. It allows us to handle error conditions that occur during program execution. Wrapping errors and unwrapping errors are two common techniques for error handling in Go that provide finer control over error handling.

Wrapping Errors

Error wrapping allows us to wrap one error type with another, thus creating errors with richer context. By doing this, we can provide additional information about the source and cause of the error, which facilitates more robust error handling.

import (
    "errors"
    "fmt"
)

type DBError struct {
    error
}

func (e *DBError) Unwrap() error {
    return e.error
}

func main() {
    // 原始数据库错误
    origErr := errors.New("database connection failed")

    // 包装数据库错误
    wrappedErr := &DBError{
        error: fmt.Errorf("failed to connect to database: %w", origErr),
    }

    // 处理包装后的错误
    switch {
    case errors.Is(wrappedErr, errors.New("database connection failed")):
        fmt.Println("Database connection failed.")
    }
}

In the above example, the DBError type wraps the original database error (origErr) and provides additional contextual information. We use fmt.Errorf to create the wrapped error, and the errors.Is function is used to compare whether the wrapped error matches the original database error.

Expanding Errors

Expanding errors is a mechanism for traversing a chain of nested errors until the lowest level error is found. This is useful for understanding the root cause of errors as well as for debugging purposes.

import (
    "fmt"
)

func f1(s string) error {
    if s == "" {
        return errors.New("empty string")
    }
    return nil
}

func f2(s string) error {
    if err := f1(s); err != nil {
        return fmt.Errorf("f1() failed: %w", err)
    }
    return nil
}

func main() {
    // 嵌套错误
    err := f2("")

    for {
        // 检查错误是否为 nil
        if err == nil {
            break
        }

        // 展开错误
        fmt.Println(err)
        err = errors.Unwrap(err)
    }
}

In the above example, the f2 function wraps the errors of the f1 function. The errors.Unwrap function is used to unwrap nested errors, allowing us to traverse the error chain and print each error.

By using a combination of wrapping errors and unwrapping errors, we can effectively handle error conditions in Go programs and provide richer error context and better debugging capabilities.

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