What's difference between all these ways of making an http request in Go?-CodePudding

What's the difference between:

url := "https://grantpitt.com"
req, _ := http.NewRequest("Get", url, nil)
res, _ := http.DefaultClient.Do(req)

reader := strings.NewReader("")
req, _ := http.NewRequest("Get", url, reader)
res, _ := http.DefaultClient.Do(req)

req, _ := http.NewRequest("Get", url, nil)
client := &http.Client{}
res, _ := client.Do(req)

resp, err := http.Get(url)

The docs say something something about custom headers or handling between these methods. What's wierd is that methods 1-3 return '400 Bad Request' while method 4 performs as expected. Why is this? Is there some headers that don't get set in methods 1-3? How would I troubleshoot this?

CodePudding user response：

In 1,2,3 you ought to replace "Get" with "GET".

In 2, the 3rd argument for NewRequest("Get", url, reader) is used to supply the request body. Since a GET request does not have body, it should be set to nil instead. The body argument is useful for other methods like POST.

4 is just a short form for the same request you do in 3.

req, _ := http.NewRequest("Get", url, nil) gives you more control over the request, compared to http.Get(url), since you can set request options before sending.

CodePudding user response：

The request method should be an all uppercase "GET" rather than "Get". For why someone would prefer one method shown over another, see the docs.