Introduction
When building REST APIs for real-world applications (like e-commerce apps, banking systems, or social platforms), updating data efficiently and safely is critical. Two HTTP methods—PUT and PATCH—are specifically designed for updating resources, but they are often misunderstood or used interchangeably.
This confusion can lead to issues like unnecessary data transfer, accidental data loss, or poor API design.
In this article, we will deeply understand:
What PUT and PATCH methods are
How they work internally
Real-world use cases and scenarios
Key differences in a comparison table
Advantages and disadvantages of each
The goal is to help you design clean, scalable, and production-ready REST APIs.
What Is a REST API?
A REST API (Representational State Transfer) is an architectural style that allows communication between client and server using HTTP protocols.
It follows standard HTTP methods:
Each request operates on a resource (like a user, product, or order).
What Is the PUT Method?
PUT is an HTTP method used to completely replace an existing resource with a new version.
Definition:
PUT updates the entire resource by sending a full representation of that resource to the server. If some fields are missing, they may be removed or reset.
How PUT Works Internally
When a PUT request is sent:
The server locates the resource using the given ID or URL
The existing resource is replaced with the new data
Any missing fields may be overwritten or set to default values
Key Characteristics of PUT
Example of PUT Request
Existing user:
{
"id": 1,
"name": "Rahul",
"email": "[email protected]",
"age": 25
}
PUT request:
PUT /api/users/1
{
"id": 1,
"name": "Rahul Sharma",
"email": "[email protected]",
"age": 26
}
Here, the entire object is replaced.
Real-Life Scenario (PUT)
Imagine editing your full profile form on a website. You rewrite all fields and submit the entire form again.
What Is the PATCH Method?
PATCH is used to update only specific fields of a resource without affecting the rest of the data.
Definition:
PATCH applies partial modifications to a resource by sending only the fields that need to be changed.
How PATCH Works Internally
The server identifies the resource
Only the provided fields are updated
Remaining fields stay unchanged
PATCH often uses formats like JSON Patch or Merge Patch.
Key Characteristics of PATCH
Partial updates
Efficient (smaller payload)
Not always idempotent (depends on implementation)
More flexible but slightly complex
Example of PATCH Request
PATCH /api/users/1
{
"email": "[email protected]"
}
Only the email field changes.
Real-Life Scenario (PATCH)
You log in and update only your phone number without touching other profile details.
Difference Between PUT and PATCH
| Feature | PUT Method | PATCH Method |
|---|
| Definition | Replaces entire resource | Updates partial resource |
| Data Sent | Full object | Only changed fields |
| Idempotency | Always idempotent | May or may not be idempotent |
| Risk | Can overwrite data | Safer for small updates |
| Performance | Higher payload | Lower payload |
| Use Case | Full update | Partial update |
| Complexity | Simple | Slightly complex |
Real-World Use Cases
When to Use PUT (Production Scenarios)
Updating full user profile in admin panel
Replacing entire product details in inventory systems
Synchronizing data from external systems
Example:
An admin updates all product details including name, price, stock, and category.
When to Use PATCH (Production Scenarios)
Updating user email or password
Changing order status (e.g., Pending → Shipped)
Updating a single setting in a large configuration object
Example:
In an e-commerce app, only order status changes—not the entire order.
ASP.NET Core Practical Example
PUT Example
[HttpPut("{id}")]
public IActionResult UpdateUser(int id, User user)
{
var existingUser = _context.Users.Find(id);
if (existingUser == null)
return NotFound();
existingUser.Name = user.Name;
existingUser.Email = user.Email;
existingUser.Age = user.Age;
_context.SaveChanges();
return Ok(existingUser);
}
PATCH Example
[HttpPatch("{id}")]
public IActionResult PatchUser(int id, JsonPatchDocument<User> patchDoc)
{
var user = _context.Users.Find(id);
if (user == null)
return NotFound();
patchDoc.ApplyTo(user);
_context.SaveChanges();
return Ok(user);
}
Advantages of PUT
Clear and predictable behavior
Easy to implement and debug
Ensures full consistency of data
Disadvantages of PUT
Advantages of PATCH
Disadvantages of PATCH
More complex to implement
Requires proper validation
Can lead to inconsistent state if misused
Before vs After Understanding
Before:
After:
Common Mistakes to Avoid
Using PUT for partial updates
Not validating PATCH data
Ignoring idempotency
Overwriting important fields accidentally
Summary
Understanding the difference between PUT and PATCH is not just a theory—it directly impacts performance, scalability, and reliability of your API.
In simple terms:
Mastering this concept will help you design better APIs that are efficient, maintainable, and production-ready.