How do I handle errors using the context package in Go?

How do I handle errors using the context package in Go?

In Go, the context package is primarily used for managing deadlines, cancellation signals, and carrying request-scoped values. To handle errors effectively, you can pass a context.Context to your functions and check for errors at each step.

Can you give me an example of how to implement this?

Sure! Here's a simple example:

func fetchData(ctx context.Context) error {
    // Simulate a process that might return an error
    select {
    case <-time.After(2 * time.Second): // Simulate delay
        return nil // No error
    case <-ctx.Done():
        return ctx.Err() // Return context error if cancelled
    }
}

In this example, if the context is cancelled, the function will return the context's error.

What if I want to handle multiple errors?

You can wrap your function calls in a loop and collect errors. For example:

var wg sync.WaitGroup
var mu sync.Mutex
var errors []error

for _, item := range items {
    wg.Add(1)
    go func(item Item) {
        defer wg.Done()
        if err := fetchData(ctx); err != nil {
            mu.Lock()
            errors = append(errors, err)
            mu.Unlock()
        }
    }(item)
}
wg.Wait()
return errors

This way, you can handle multiple errors concurrently.