PUT vs PATCH: Understanding the Difference

When working with RESTful APIs, two HTTP methods that often confuse developers are PUT and PATCH. Both are used to update resources, but they have distinct purposes and use cases. In addition, the PUT method is often compared to the POST method as well. In this article, we’ll explore the differences between PUT and PATCH, as well as the comparisons between PUT and POST, to help you understand when and how to use each of these HTTP methods effectively.

PUT Method

Purpose

The PUT method is primarily used for updating or replacing an existing resource with a new version. When you send a PUT request to a resource’s endpoint, it is assumed that you are sending the complete representation of the resource. If the resource already exists, the server will replace it with the new data provided in the request. If the resource doesn’t exist, a new resource will be created with the given data at the specified URL.

Example Code

PUT /api/users/123 HTTP/1.1
Host: example.com
Content-Type: application/json

{
    "name": "John Doe",
    "email": "[email protected]"
}

In this example, a PUT request is made to update the user with ID 123. The entire user resource, including the name and email, is provided in the request body.

Use Cases

• Full resource updates: PUT is ideal when you need to update all fields of a resource, and you want to ensure the resource is replaced entirely with the new data.

PATCH Method

Purpose

PATCH, on the other hand, is used for partial updates to a resource. When you send a PATCH request, you are only providing the specific fields that need to be updated, leaving the rest of the resource unchanged. This is particularly useful when you want to make minor modifications without overwriting existing data.

Example Code

PATCH /api/users/123 HTTP/1.1
Host: example.com
Content-Type: application/json

{
    "email": "[email protected]"
}

In this PATCH request, only the email field is being updated for the user with ID 123. The name field remains untouched.

Use Cases

• Partial updates: PATCH is suitable when you want to modify specific attributes of a resource while preserving the existing data.
• Optimizing network usage: PATCH requests are more bandwidth-efficient compared to PUT, especially when dealing with large resources.

PUT vs. POST

While PUT and PATCH are both used for resource updates, POST serves a different purpose in RESTful APIs.

POST Method

Purpose

POST is used to create a new resource. When you send a POST request, you’re essentially asking the server to create a new resource at a URL it chooses. The server usually responds with the URL of the newly created resource in the response.

Example Code

POST /api/users HTTP/1.1
Host: example.com
Content-Type: application/json

{
    "name": "Jane Smith",
    "email": "[email protected]"
}

In this POST request, a new user is being created. The server will generate a unique URL for this user, and it will respond with the URL where the user can be accessed.

Use Cases

• Resource creation: POST is used when you want to create a new resource on the server.
• Uncertain URL: POST requests don’t require the client to specify the resource’s URL; the server decides where to place it.

Comparison Chart

Here’s a summary of the differences between PUT, PATCH, and POST:

Best Practices for Using PUT, PATCH, and POST

Now that we have a clear understanding of PUT, PATCH, and POST HTTP methods and their purposes, let’s delve into some best practices and considerations when working with these methods.

PUT Best Practices

1. Use PUT for Full Resource Updates: PUT should be used when you want to completely replace an existing resource with a new representation. Ensure that the entire resource, including all its attributes, is provided in the request payload.
2. Include the Resource Identifier: The URL used for the PUT request should contain the identifier of the resource being updated. This identifier should match the resource being replaced.
3. Idempotent Operation: PUT requests should be idempotent, meaning that making the same request multiple times should have the same result as making it once. This allows for safe retries in case of network issues.

PATCH Best Practices

1. Use PATCH for Partial Updates: PATCH is ideal when you want to make minor changes to specific attributes of a resource while leaving the rest of the resource unchanged.
2. Document Supported Fields: Clearly document which fields can be updated using PATCH for each resource type in your API. This helps clients understand what changes they can make.
3. Partial Updates Should Be Idempotent: Like PUT, PATCH requests should also be idempotent. Repeating the same PATCH request multiple times should not produce different results.

POST Best Practices

1. Use POST for Resource Creation: POST is the standard method for creating new resources on the server. The server should respond with a representation of the newly created resource.
2. Include Resource Data: Ensure that the request payload contains all the necessary data to create the resource. The server should provide a meaningful response that includes the URL of the newly created resource.
3. Non-Idempotent Operation: Unlike PUT and PATCH, POST requests are non-idempotent. Multiple identical POST requests may result in the creation of multiple resources.

Handling Errors

Regardless of the HTTP method used, it’s important to handle errors gracefully in your API:

• Use appropriate HTTP status codes (e.g., 200 for success, 201 for resource creation, 204 for no content, 400 for bad requests, and 404 for not found) to indicate the outcome of the request.
• Provide informative error messages in the response payload to help clients understand and troubleshoot issues.

Security Considerations

Security should be a top priority when designing your API:

• Always use HTTPS to encrypt data transmitted between clients and the server.
• Implement authentication and authorization mechanisms to ensure that only authorized users can perform PUT, PATCH, or POST operations.
• Validate user input to prevent malicious or erroneous data from being processed.

Versioning

As your API evolves, consider versioning to maintain backward compatibility. This allows clients to continue using older versions of your API while adopting new ones. Versioning can be achieved through URL paths (e.g., /v1/resource) or using custom request headers.

Conclusion

PUT, PATCH, and POST are essential HTTP methods for creating, updating, and managing resources in RESTful APIs. Understanding their differences and best practices for their usage is vital for designing efficient and reliable APIs. By following these guidelines and considering security and versioning, you can build robust APIs that provide a seamless experience for clients while maintaining data integrity and security.