Rest API in Go

On the previous post we learned how to return JSON responses in Go, now we will see how to build our first Rest API.

Let’s modify our previous example to have a route to handle the member resource:

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package main

import (
        "encoding/json"
        "io/ioutil"
        "net/http"
)

var members = []Member{Member{"someuser", "someuser@somedomain.com"}}

type Member struct {
        Login string
        Email string
}

func main() {
        http.HandleFunc("/members", membersHandler)
        http.ListenAndServe(":8080", nil)
}

func membersHandler(w http.ResponseWriter, r *http.Request) {
        w.Header().Set("Content-Type", "application/json")

        if r.Method == "GET" {
                j, _ := json.Marshal(members)

                w.Write(j)
        }

        if r.Method == "POST" {
                var m Member
                b, _ := ioutil.ReadAll(r.Body)
                json.Unmarshal(b, &m)

                members = append(members, m)

                j, _ := json.Marshal(m)
                w.Write(j)
        }
}

On line 17 we changed the first parameter from "/" to "/members", now our membersHandler will only handle requests to the /members endpoint.

The membersHandler function:

Sets the "Content-Type" header to application/json.
Checks if the request method is GET, if so it just returns all the members.
If the method is POST it saves the new member to the members array and then returns the newly created member.

When we issue a GET /members then we will see the following response:

$ curl -i localhost:8080/members
HTTP/1.1 200 OK
Content-Type: application/json
Content-Length: 56

[{"Login":"someuser","Email":"someuser@somedomain.com"}]%

We can also create a new member:

$ curl -d '{"Login":"anotheruser", "Email": "another@somedomain.com"}' -i localhost:8080/members
HTTP/1.1 200 OK
Content-Type: application/json
Content-Length: 56

{"Login":"anotheruser","Email":"another@somedomain.com"}%

The following posts I will show you how to have smarter routes and how to persist your members using MongoDB.

rodrigosaito.com

Rest API in Go