How to handle multiple errors in Go and aggregate them into a single error?

In Go, you can handle multiple errors and aggregate them into a single error using the multierror package or by creating a custom error type. Here's how you can do it:

Using the multierror package:

Import the multierror package:

import "github.com/hashicorp/go-multierror"

Create a new multierror object:

errs := new(multierror.Error)

Perform your operations that can result in errors, and append each error to the multierror object:

err1 := operation1()
if err1 != nil {
    errs = multierror.Append(errs, err1)
}

err2 := operation2()
if err2 != nil {
    errs = multierror.Append(errs, err2)
}

// Add more operations and error checks if needed...

Check if any errors occurred and handle them:

if errs.ErrorOrNil() != nil {
    // Handle errors
    fmt.Println(errs.Error())
}

Creating a custom error type:

Create a custom error struct to hold multiple errors:

type MyError struct {
    Errors []error
}

// Implement the Error() function for MyError struct
func (e *MyError) Error() string {
    var errorMsg string
    for _, err := range e.Errors {
        errorMsg += err.Error() + "\n"
    }
    return errorMsg
}

Create a new MyError object and append errors to it:

errs := &MyError{}

err1 := operation1()
if err1 != nil {
    errs.Errors = append(errs.Errors, err1)
}

err2 := operation2()
if err2 != nil {
    errs.Errors = append(errs.Errors, err2)
}

// Add more operations and error checks if needed...

Check if any errors occurred and handle them:

if len(errs.Errors) > 0 {
    // Handle errors
    fmt.Println(errs.Error())
}

With these approaches, you can aggregate multiple errors into a single error and handle them as needed.