PathVariable vs RequestParam in Spring Boot: When to use them

In Spring Boot, annotations like @PathVariable and @RequestParam are used to handle HTTP request data in different ways

The similarities between them are

• they are both used in RestController methods
• they work with other annotations like GetMapping, PostMapping etc.

The difference between them is what we are going to explore and understand in this article.

@PathVariable Annotation

if you have a url like this - http://example.com/posts - for creating a post

you simply write a method in the Controller like so

In a real word app, you would definitely want to be able to get a post by passing the 'id' somewhere and, that is where a @PathVariable is useful.

to get a particular post by passing the 'id', you would want the url to look like this - http://example.com/posts/1 - and this translates to us writing the Controller method this way.

the 'id' parameter in the getPostById method must also match the parameter in the @GetMapping annotation.


If you want it to have a different name, @PathVariable has a property called 'name' and the method ends up looking like this

There is another property called 'required' that has a default value of true, if the client calling the endpoint does not pass the 'id' in the url, an exception is thrown.

@RequestParam Annotation

@RequestParam is mostly used when there is an endpoint you can query for data, like searching for a particular data according to some attributes.

For example, if we want to create an endpoint where a client can search for a post/posts by passing the Post’s tag and number of likes, the controller method will be written this way

and the url will look this way http://example.com/posts?tag=cooking&likes=50

Depending on your design, this endpoint could mean - get the list of posts where the tag equals cooking and it has at least 50 likes

You can have as many @RequestParam as you want, and also note that any or all of them can be optional.

Notice that the question mark makes the difference between a URL that just needs a @PathVariable and another that needs a @RequestParam.

Another thing to note is this - @RequestParam does not need you passing the 'tag' parameter in the @GetMapping annotation.

@RequestParam also has a 'name' and 'required' property like @PathVariable.

@RequestParam has a 'defaultValue' property for when the parameter is not provided when the endpoint is called.

In summary,

@PathVariable is used when the URL structure defines variables, such as resource identifiers in a RESTful API.

@RequestParam is used for optional or required query parameters in an http request.