Powerful Command-Line Applications in Go/

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Completing the REST API Server

Completing the REST API Server

Complete the REST API server and connect it with the to-do API.

We'll cover the following...

Structure of the API server

With the general structure of our API server ready, let’s add the CRUD operations for the to-do list.

Our to-do REST API supports these operations.

To-do REST API Operations

Method

URL

Description

GET

/todo

Retrieve all to-do items

GET

/todo/{number}

Retrieve a to-do item {number}

POST

/todo

Create a to-do item

PATCH

/todo/{number}?complete

Mark a to-do item {number} as completed

DELETE

/todo/{number}

Delete a to-do item {number}

The REST API serves all to-do-related content using the /todo URL path. It handles different operations based on the HTTP method, path, and parameters. The path might include a number for operations that act on a single to-do item. For example, to delete the third item from the list, the user sends a DELETE request to the URL path /todo/3.

REST API responds

The first two GET operations on the list retrieve items from the list. For this example, the REST API responds with JSON data. Besides the to-do items, we want to include additional information with the response, such as the current date and the number of results included. A sample response for multiple items looks like this:

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{
  "results": [
    {
      "Task": "Task Number 1",
      "Done": true,
      "CreatedAt": "2019-10-13T11:16:00.756817096-04:00",
      "CompletedAt": "2019-10-13T21:25:30.008877148-04:00"
    },
    {
      "Task": "Task Number 2",
      "Done": false,
      "CreatedAt": "2019-10-14T15:55:48.273514272-04:00",
      "CompletedAt": "0001-01-01T00:00:00Z"
    }
  ],
  "date": 1575922413,
  "total_results": 2
}

Creating the todoResponse.go file

The response includes the field results that wraps the to-do list. Let’s create a new type todoResponse to wrap the list. In the same directory where we have main.go, we create a new file todoResponse.go. We add the package definition and the import section.

For this file, we’re using the following packages:

  • encoding/json to customize JSON output.
  • time to work with time functions.
  • interacting/todo.
package main
import (
  "encoding/json"
  "time"
  "todo"
)
Importing the required list

Then, we add the new struct type todoResponse to wrap the todo.List type:

type todoResponse struct {
  Results todo.List `json:"results"`
}

In this struct type, the field name Results is exported with the first character of its name capitalized. This ensures that it’s exported as JSON when using Go’s JSON encoding. We’re using a struct tag to change the name to results in the resulting JSON as it’s common to have all fields in JSON spelled with lowercase characters.

Using struct tags is the best way to do simple JSON ...