POST Requests

The body of the request is the payload sent to the server. The special Content-Type header is used to tell the server the format of the body: application/json for JSON data in our case. POST requests are generally not safe methods to call multiple times because that would create duplicate records. For example, you wouldn't want to accidentally send a tweet twice.

Like http.Get, the standard library's http.Post function can be used to send simple POST requests. The trouble is, it's a bit limited. And because we need to add an X-API-Key header, the simple http.Post function won't work for us. Instead, we need to use http.NewRequest:

type Comment struct {
	Id      string `json:"id"`
	UserId  string `json:"user_id"`
	Comment string `json:"comment"`
}

func createComment(url, apiKey string, commentStruct Comment) (Comment, error) {
    // encode our comment as json
	jsonData, err := json.Marshal(commentStruct)
	if err != nil {
		return Comment{}, err
	}

    // create a new request
	req, err := http.NewRequest("POST", url, bytes.NewBuffer(jsonData))
	if err != nil {
		return Comment{}, err
	}

    // set request headers
	req.Header.Set("Content-Type", "application/json")
    req.Header.Set("X-API-Key", apiKey)

    // create a new client and make the request
	client := &http.Client{}
	res, err := client.Do(req)
	if err != nil {
		return Comment{}, err
	}
	defer res.Body.Close()

    // decode the json data from the response
	// into a new Comment struct
	var comment Comment
	decoder := json.NewDecoder(res.Body)
	err = decoder.Decode(&comment)
	if err != nil {
		return Comment{}, err
	}

	return comment, nil
}

Complete the createUser function. It should:

1. Take a URL and apiKey string, and User data as parameters
2. Encode the user data using json.Marshal
3. Create a new POST request using http.NewRequest. Use a bytes.NewBuffer to create an io.Reader from the JSON data.
4. Modify the request headers:
   • Set the Content-Type header, with application/json as its value
   • Set the X-API-Key header, with apiKey as its value
5. Make the request using the http.Client's Do method. You can create a new *http.Client or use the http.DefaultClient
6. Decode and return the response's JSON body (which is also a User)

Don't copy paste from the code above. Type it out and understand what each line does.