Understanding HTTP Methods

Your device communicates with a server through HTTP requests when browsing the web, submitting forms or using applications. Each request will include an HTTP method indicating what action needs to be performed on the server. For example, a request may have the means to ask the server to provide information (GET), create information (POST), update information (PUT), delete information (DELETE) etc.

If you are going to work with REST APIs one of your first major learnings will be around the usage of HTTP methods. One of the first items that you may want to understand in relation to using REST APIs is understanding how query parameters work because most of the requests you will use in REST API will consist of query parameters.

Query Parameters

Query parameters don’t refer to an HTTP method. They improve how APIs perform. They allow for information to be sent to the server via the URL format.

In the URL, the query parameters are after the question mark (`?`). Query parameters include the key-value pair. The parameters are separated by `&`, when there is multiple.

The syntax is as follows:

endpoint?key1=value1&key2=value2&key3=value3

Here:

• `endpoint` is the API resource you're asking for.

• `?` starts the query parameters.

•  Each key-value pair gives information to the server.

• `. Separates multiple query parameters.

One big advantage of query parameters is that they let one API endpoint handle types of requests. Of creating separate endpoints for searching, filtering or pagination developers can use one endpoint and change the query parameters to get different results.

In real-life applications query parameters are often used to:

•  Filter data based on conditions.

•  Search for records using keywords.

•  Sort results in ascending or descending order.

•  Display data page by page using pagination.

•  Limit the number of records returned.

For example, imagine you're browsing a shopping website. The same `/products` endpoint can show all products, electronic items or products from a brand depending on the query parameters.

Example

HTTP

GET /products?category=electronics&brand=apple&page=2

Let’s analyze this request.

• `/products` is the API endpoint for product details.

• Query parameters begin with `?`.

• `category=electronics` tells the server to return electronics products.

• `brand=apple` filters the results to include Apple products.

• `page=2` requests the page of filtered results.

The endpoint itself doesn't change. The request is still sent to `/products`. There can be changes in response according to the parameters used in the request. For example, changing the request parameter category from electronics to clothing will return the products of clothing items.

HTTP Methods

HTTP methods define what action to take on a resource.

GET

The GET method is used to adapt information from the server with the request for data but without modifying any resource on the server. GET is the most widely used HTTP method. Whenever GET is used it means that data is required from the server.

POST

POST is about sending data to the server for the purpose of creating a new resource, for example, user creation or form filling. Thus, whenever one uses POST, it means that someone is sending the information to the server for creating a new resource.

PUT

PUT is used for replacing the old resource with a new one. Once you use this method you will see a request created for you with a new version of the old resource used in it.

PATCH

The PATCH method allows a user only to modify existing records without having to replace them with the new one. PATCH works great if there is a need to edit something in the record.

DELETE

The DELETE method allows deleting resources on the server when there is no need for them any longer. In fact it means that once a DELETE request is served, the corresponding resource has been deleted from the server.

Final Thoughts

All of the HTTP methods and query parameters work together to provide better APIs. Understanding these concepts makes reading and building REST APIs simpler. HTTP methods define what action to take while query parameters provide details that customize the request.