Copy from an io Reader in chunks

I am quite new to Golang and am experimenting with API creation. To create a mock endpoint, I want to take my request body, and copy it to a discard writer in chunks, while sleeping a brief amount of time in between each read.

I currently have a function which copies the body to a discard writer in one go:

_, err := io.Copy(io.Discard, r.Body)
if err != nil {
    w.WriteHeader(http.StatusInternalServerError)
    return
}

but want to do something more like CopyN(io.Discard, r.Body, 10) in a loop and sleep after each chunk.

I can't find great documentation on how to do this, any advice would be greatly appreciated!

Answer

Use the for statement to call CopyN(io.Discard, r.Body, 10) in a loop and sleep after each chunk.

for {
    _, err := io.CopyN(io.Discard, r.Body, 10)
    if err == io.EOF {
        // Body successfully discarded.
        break
    } else if err != nil {
        log.Fatal(err)
    }
    time.Sleep(time.Second)
}