Link relations in responses in Rest API

Introduction

Link relations help clients understand how different parts of an API response connect to each other. They make navigation and interaction easier by showing what links mean.

When you want to guide users to related resources in an API response.

When you want to provide navigation links like next page or previous page in paginated data.

When you want to describe the purpose of a link, like 'edit', 'delete', or 'self'.

When you want to make your API responses more self-explanatory and easier to use.

When you want to follow REST API best practices for discoverability.

Syntax

Rest API

{
  "_links": {
    "self": { "href": "URL to this resource" },
    "related": { "href": "URL to related resource" },
    "next": { "href": "URL to next page/resource" }
  },
  "data": { ... }
}

The _links object groups all link relations in the response.

Each link relation has a name (like self, next) and an href URL.

Examples

This response shows a user with links to itself and to the user's friends.

Rest API

{
  "_links": {
    "self": { "href": "/users/123" },
    "friends": { "href": "/users/123/friends" }
  },
  "name": "Alice"
}

This response includes pagination links to navigate between pages of articles.

Rest API

{
  "_links": {
    "self": { "href": "/articles?page=2" },
    "next": { "href": "/articles?page=3" },
    "prev": { "href": "/articles?page=1" }
  },
  "articles": [ ... ]
}

Sample Program

This Flask API returns a user with link relations to itself and to the user's friends. The _links object helps clients find related resources easily.

Rest API

from flask import Flask, jsonify, url_for

app = Flask(__name__)

@app.route('/users/<int:user_id>')
def get_user(user_id):
    user_data = {"id": user_id, "name": "Alice"}
    links = {
        "self": {"href": url_for('get_user', user_id=user_id)},
        "friends": {"href": url_for('get_user_friends', user_id=user_id)}
    }
    response = {"_links": links, **user_data}
    return jsonify(response)

@app.route('/users/<int:user_id>/friends')
def get_user_friends(user_id):
    friends = ["Bob", "Charlie"]
    return jsonify({"user_id": user_id, "friends": friends})

if __name__ == '__main__':
    app.run(debug=True)

Important Notes

Use standard link relation names like self, next, prev when possible.

Link relations improve API usability and help clients discover related data without guessing URLs.

Summary

Link relations group URLs in API responses to show how resources connect.

They make APIs easier to navigate and understand.

Use _links with named relations like self and next.