The main differences between the HTTP
`POST` and
`PUT` methods are their intended purposes and the way they handle data:
1. Purpose:
- `POST`: The `POST` method is used to send data to the server to create a new resource. It is often used when submitting forms or sending data that needs to be processed and stored on the server. Each `POST` request typically creates a new resource on the server, and the server assigns a unique identifier to it.
- `PUT`: The `PUT` method is used to send data to the server to update an existing resource or create a resource at a specific URL. It is used when you know the exact location of the resource you want to update or create. A `PUT` request can either update an existing resource or create a new one if it doesn't already exist at the specified URL.
2. Idempotence:
- `POST`: `POST` requests are not idempotent. Sending the same `POST` request multiple times may result in the creation of multiple resources with different identifiers or cause repeated side effects on the server.
- `PUT`: `PUT` requests are idempotent. Making the same `PUT` request multiple times will have the same outcome, ensuring that the resource on the server is updated or created consistently.
3. Data Handling:
- `POST`: Data is sent in the body of the HTTP request, typically as form data or serialized JSON/XML. The server processes this data and performs the necessary actions to create a new resource.
- `PUT`: Data is sent in the body of the HTTP request, similar to the `POST` method. However, in a `PUT` request, the data represents the complete updated representation of the resource. The server uses this data to replace the existing resource or create a new one.
4. URL Convention:
- `POST`: The URL for a `POST` request typically points to a collection endpoint or a general resource endpoint. For example, `https://example.com/api/users` to create a new user.
- `PUT`: The URL for a `PUT` request usually points to a specific resource or a unique identifier for that resource. For example, `https://example.com/api/users/123` to update the user with the ID "123".
5. Safe Operations:
- `POST`: `POST` requests are not considered safe operations as they can result in the creation of new resources or have side effects on the server.
- `PUT`: `PUT` requests are not considered safe operations either, as they can update or create resources on the server.
Example:
Here are examples that demonstrate the difference between the `POST` and `PUT` methods:
1. `POST` Method Example:
Let's say you have an API that handles blog posts. To create a new blog post, you would use a `POST` request. Here's an example using JavaScript's `fetch` API:
const newPost = {
title: 'My New Blog Post',
content: 'This is the content of my new blog post.'
};
fetch('https://example.com/api/posts', {
method: 'POST',
headers: {
'Content-Type': 'application/json'
},
body: JSON.stringify(newPost)
})
.then(response => response.json())
.then(data => {
console.log(data);
})
.catch(error => {
console.error('Error:', error);
});
In this example, the `POST` request is made to the URL `https://example.com/api/posts`, indicating that you want to create a new blog post. The server will process the request, create a new blog post with the provided data (`newPost`), and respond with the created post details.
2. `PUT` Method Example:
Suppose you have an API that manages user profiles, and you want to update an existing user's information. To achieve that, you would use a `PUT` request. Here's an example using JavaScript's `fetch` API:
const updatedUser = {
name: 'Jane Doe',
email: 'jane@example.com'
};
fetch('https://example.com/api/users/123', {
method: 'PUT',
headers: {
'Content-Type': 'application/json'
},
body: JSON.stringify(updatedUser)
})
.then(response => response.json())
.then(data => {
console.log(data);
})
.catch(error => {
console.error('Error:', error);
});
In this example, the `PUT` request is made to the URL `https://example.com/api/users/123`, indicating that you want to update the user with the ID "123". The server will process the request, replace the existing user's information with the provided data (`updatedUser`), and respond with the updated user details.
Conclusion:
In summary, the `POST` method is used to send data to create a new resource, while the `PUT` method is used to send data to update an existing resource or create a new one at a specific URL. `POST` requests create new resources, are not idempotent, and send data representing the resource to be created. `PUT` requests update or create resources, are idempotent, and send data representing the complete updated representation of the resource.