REST API Tutorial

 🚀 Introduction

REST APIs allow different applications to communicate with each other.

Each API request uses a specific HTTP Method based on the action:

Method	Action	Meaning
GET	Read	Fetch data from server
POST	Create	Add new data
PUT	Update	Replace existing data
PATCH	Modify	Modify part of existing data
DELETE	Remove	Delete data

We will use live working APIs from:

👉 https://restful-api.dev/

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📥 1. GET — Retrieve / Read Data

➤ Example 1: Fetch multiple items using IDs

🔗 API URL:

https://api.restful-api.dev/objects?id=4&id=6&id=10

🟦 cURL Example (GET)

curl --location 'https://api.restful-api.dev/objects?id=4&id=6&id=10' \
--data ''

📌 Example Response:

[
    {
        "id": "4",
        "name": "Apple iPhone 11, 64GB",
        "data": {
            "price": 389.99,
            "color": "Purple"
        }
    },
    {
        "id": "6",
        "name": "Apple AirPods",
        "data": {
            "generation": "3rd",
            "price": 120
        }
    },
    {
        "id": "10",
        "name": "Apple iPad Mini 5th Gen",
        "data": {
            "Capacity": "64 GB",
            "Screen size": 7.9
        }
    }
]

➤ Example 2: Fetch a specific object by ID

🔗 API URL:

https://api.restful-api.dev/objects/ff8081819782e69e019a41218336270d

🟦 cURL Example (GET)

curl --location 'https://api.restful-api.dev/objects/ff8081819782e69e019a41218336270d' \
--data ''

📌 Example Response:

{
    "id": "ff8081819782e69e019a41218336270d",
    "name": "Apple Testing update MacBook Pro 16",
    "data": {
        "year": 2019,
        "price": 1849.99,
        "CPU model": "Intel Core i9",
        "Hard disk size": "1 TB"
    }
}

✅ GET only retrieves data, it never modifies.

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➕ 2. POST — Create Data

📌 Used when you want to add a new record into server/database.

🔗 API URL:

https://api.restful-api.dev/objects

📦 Request Body:

{
   "name": "Apple Testing MacBook Pro 16",
   "data": {
      "year": 2019,
      "price": 1849.99,
      "CPU model": "Intel Core i9",
      "Hard disk size": "1 TB"
   }
}

🟦 cURL Example (POST)

curl --location 'https://api.restful-api.dev/objects' \
--header 'Content-Type: application/json' \
--data '{
   "name": "Apple Testing MacBook Pro 16",
   "data": {
      "year": 2019,
      "price": 1849.99,
      "CPU model": "Intel Core i9",
      "Hard disk size": "1 TB"
   }
}'

📌 Example Response:
{
    "id": "ff8081819782e69e019a44762e9b2aee",
    "name": "Apple Testing MacBook Pro 16",
    "createdAt": "2025-11-02T12:06:27.227+00:00",
    "data": {
        "year": 2019,
        "price": 1849.99,
        "CPU model": "Intel Core i9",
        "Hard disk size": "1 TB"
    }
}

✅ POST creates a new record and server generates an ID.

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🔄 3. PUT — Update (Replace everything)

📌 Used to replace the entire object with new values.

🔗 API URL:

https://api.restful-api.dev/objects/ff8081819782e69e019a41218336270d

📦 Request Body (full update):

{
   "name": "Apple Testing update MacBook Pro 16",
   "data": {
      "year": 2019,
      "price": 1849.99,
      "CPU model": "Intel Core i9",
      "Hard disk size": "1 TB"
   }
}

🟦 cURL Example (PUT)

curl --location --request PUT 'https://api.restful-api.dev/objects/ff8081819782e69e019a41218336270d' \
--header 'Content-Type: application/json' \
--data '{
   "name": "Apple Testing update MacBook Pro 16",
   "data": {
      "year": 2019,
      "price": 1849.99,
      "CPU model": "Intel Core i9",
      "Hard disk size": "1 TB"
   }
}'

📌 Example Response:
{
    "id": "ff8081819782e69e019a41218336270d",
    "name": "Apple Testing update MacBook Pro 16",
    "updatedAt": "2025-11-02T12:08:01.394+00:00",
    "data": {
        "year": 2019,
        "price": 1849.99,
        "CPU model": "Intel Core i9",
        "Hard disk size": "1 TB"
    }
}
✅ PUT replaces the entire existing object.

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✏ 4. PATCH — Update (Partial)

📌 Used when you want to update only one field, not the entire object.

🔗 API URL:

https://api.restful-api.dev/objects/ff8081819782e69e019a41218336270d

📦 Request Body (only updating name):

{
   "name": "Apple MacBook Pro 16 (Updated Name)"
}

🟦 cURL Example (PATCH)

curl --location --request PATCH 'https://api.restful-api.dev/objects/ff8081819782e69e019a41218336270d' \
--header 'Content-Type: application/json' \
--data '{
   "name": "Apple MacBook Pro 16 (Updated Name)"
}'

📌 Example Response:

{
    "id": "ff8081819782e69e019a41218336270d",
    "name": "Apple MacBook Pro 16 (Updated Name)",
    "updatedAt": "2025-11-02T12:09:19.622+00:00",
    "data": {
        "year": 2019,
        "price": 1849.99,
        "CPU model": "Intel Core i9",
        "Hard disk size": "1 TB"
    }
}

✅ PATCH updates only the provided field, keeping the rest unchanged.

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🗑️5. DELETE — Remove Data

📌 Used to delete a record from server/database.

🔗 API URL:

https://api.restful-api.dev/objects/ff8081819782e69e019a41218336270d


🟦 cURL Example (DELETE)

curl --location --request DELETE 'https://api.restful-api.dev/objects/ff8081819782e69e019a44762e9b2aee' \
--data ''


📌 Example Response:

{
    "message": "Object with id = ff8081819782e69e019a44762e9b2aee has been deleted."
}

⬅️ After DELETE, fetching the same ID will return not found.

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🎯 Summary: When to use what?

Method	CRUD Action	Usage
GET	Read	Fetch existing data
POST	Create	Insert new record
PUT	Update	Replace full object
PATCH	Update	Modify some fields
DELETE	Delete	Remove object

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🎉 Final Notes

These APIs are great for practice using:

• Postman

• Swagger

• Java / Python / JavaScript API projects

You can now confidently use REST API methods in your applications.

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