Spring @RequestParam Annotation
- Introduction: Spring @RequestParam annotation can be used to extract the query parameters in a handler method. In this quick tutorial, we’ll learn its usage.
- @RequestParam Annotation: Let’s first expose an API which returns a list of users with a given first name and age: ...
- Attributes of @RequestParam: ...
- 1. name / value: ...
- 2. required: ...
- 3. defaultValue: ...
- @RequestParam with Java List: ...
- Retrieve All Parameters: ...
How to use @requestparam annotation in Spring MVC?
In Spring MVC, the @RequestParam annotation is used to read the form data and bind it automatically to the parameter present in the provided method. So, it ignores the requirement of HttpServletRequest object to read the provided data. Including form data, it also maps the request parameter to query parameter and parts in multipart requests.
What is @requestparam in Spring Boot?
1. Overview In this quick tutorial, we’ll explore Spring's @RequestParam annotation and its attributes. Simply put, we can use @RequestParam to extract query parameters, form parameters, and even files from the request.
What are @method parameters annotated with @requestparam?
Method parameters annotated with @RequestParam are required by default. This means that if the parameter isn’t present in the request, we'll get an error: GET /api/foos HTTP/1.1 ----- 400 Bad Request Required String parameter 'id' is not present. We can configure our @RequestParam to be optional, though, with the required attribute:
What is @requestparam required by default?
Optional Request Parameters Method parameters annotated with @RequestParam are required by default. This means that if the parameter isn’t present in the request, we'll get an error: We can configure our @RequestParam to be optional, though, with the required attribute:
What is the use of @RequestParam?
The @RequestParam is used to read the HTML form data provided by a user and bind it to the request parameter. The Model contains the request data and provides it to view page.
Is RequestParam mandatory?
Method parameters annotated with @RequestParam are required by default. will correctly invoke the method. When the parameter isn't specified, the method parameter is bound to null.
What is required in @RequestParam?
@RequestParam is a Spring annotation used to bind a web request parameter to a method parameter. It has the following optional elements: defaultValue - used as a fallback when the request parameter is not provided or has an empty value. name - name of the request parameter to bind to.
What is @QueryParam and @RequestParam?
@QueryParam is a JAX-RS framework annotation and @RequestParam is from Spring. Follow this answer to receive notifications.
What is RequestParam in REST API?
@RequestParam annotation enables spring to extract input data that may be passed as a query, form data, or any arbitrary custom data. Here, we will see how we can use @RequestParam when building RESTful APIs for a web-based application.
What is difference between RequestParam and RequestPart?
The main difference is that when the method argument is not a String or raw MultipartFile / Part , @RequestParam relies on type conversion via a registered Converter or PropertyEditor while RequestPart relies on HttpMessageConverters taking into consideration the 'Content-Type' header of the request part.
Can we send object as RequestParam?
You cannot use the @RequestParam annotation inside objects but it doesn't mean you're left with no other solution. In this post, I'm going to show you how to bind multiple request parameters to an object in Spring application.
What is the difference between RequestParam and PathVariable?
1) The @RequestParam is used to extract query parameters while @PathVariable is used to extract data right from the URI.
How do you send a null in RequestParam?
How to send NULL in HTTP query string?Use a constant, like "NULL" or "~" . That works for booleans & numbers, but not for strings, as that might be the desired string value.Use an empty value. Once again, that can work for booleans & numbers, but not for strings, as that might be the desired string value.
What is RequestMapping vs GetMapping?
@RequestMapping is used at the class level while @GetMapping is used to connect the methods. This is also an important Spring MVC interview question to knowing how and when to use both RequestMapping and GetMapping is crucial for Java developers.
How do I pass multiple parameters in RequestParam?
Reading Multi Value Query String Parameters Note: We can also use an Array type or a Set type. Using the parameter of Set type ensures that the query string has unique values. Let's execute a request with a comma-separated multi-value parameter. Or, we can specify the parameter multiple times with different values.
Can QueryParam be null?
@QueryParam is used to handle query parameters. The query parameter will be null if user just request http://example.com/api/orders .
Can request param be optional?
As query parameters are not a fixed part of a path, they can be optional and can have default values.
Is PathVariable required by default?
3 version, @PathVariable annotation has required attribute, to specify it is mandatorily required in URI. The default value for this attribute is true if we make this attribute value to false, then Spring MVC will not throw an exception.
Is @RequestMapping mandatory?
A @RequestMapping on the class level is not required. Without it, all paths are simply absolute, and not relative.
Are rest parameters optional?
Rest parameters are treated as a boundless number of optional parameters.
What are method parameters annotated with?
Method parameters annotated with @RequestParam are required by default.
What are the attributes of annotations?
Next, let's have a look at the annotation's attributes: name, value, required, and defaultValue.
When is the parameter bound to null?
When the parameter isn't specified, the method parameter is bound to null.
Can we have multiple parameters without defining their names?
We can also have multiple parameters without defining their names or count by just using a Map:
Can a request param have multiple values?
A single @RequestParam can have multiple values:
What is the @requestparam annotation?
The @RequestParam annotation binds the web request parameter to a controller method. In simple words, we can use the @RequestParam annotation to get values from query parameters and from parameters. Let’s take a closer looks at some important points:
What happens if you send a request without passing the name?
If we send a request without passing the “name” in the request, we will get an error back from the service.
Can request param be used to map multiple values?
The RequestParam annotation can be map multiple values in a list. Let’s take an example where we like to send multiple values as comma-separated values to the method and like to store these values as a List. Spring MVC will maps comma-separated values in the list. Let’s understand this by an example:
Can you do @requestparam with email?
We can also do @RequestParam ( name = “email”) or just @Request Param (“email”).
What happens if @requestparam is not specified on an object parameter?
From my testing, if @RequestParam is not specified on an Object parameter, Spring MVC will by default try to bind to the internal properties of that object.
What does "two B or not two B" mean?
Two B or not two B - Farewell, BoltClock and Bhargav!
What is the meaning of "back up"?
Making statements based on opinion; back them up with references or personal experience.
Is required=false mandatory in URL?
We have some properties like required, defaultValue etc. If you provide required=false as mentioned in below line of code, the status parameter is not mandatory in URL
Overview
- In this quick tutorial, we’ll explore Spring's @RequestParamannotation and its attributes. Simply put, we can use @RequestParamto extract query parameters, form parameters, and even files from the request.
A Simple Mapping
- Let's say that we have an endpoint /api/foos that takes a query parameter called id: In this example, we used @RequestParam to extract the idquery parameter. A simple GET request would invoke getFoos: Next, let's have a look at the annotation's attributes: name, value,required, and defaultValue.
Specifying The Request Parameter Name
- In the previous example, both the variable name and the parameter name are the same. Sometimes we want these to be different, though.Or, if we aren't using Spring Boot, we may need to do special compile-time configuration or the parameter names won't actually be in the bytecode. Fortunately, we can configure the @RequestParam name using the name attribute: …
Optional Request Parameters
- Method parameters annotated with @RequestParamare required by default. This means that if the parameter isn’t present in the request, we'll get an error: We can configure our @RequestParam to be optional, though, with the required attribute: In this case, both: and will correctly invoke the method. When the parameter isn't specified, the method parameter is boun…
A Default Value For The Request Parameter
- We can also set a default value to the @RequestParam by using the defaultValueattribute: This is like required=false, in that the user no longer needs to supply the parameter: Although, we are still okay to provide it: Note that when we set the defaultValue attribute, required is indeed set to false.
Mapping All Parameters
- We can also have multiple parameters without defining their names or count by just using a Map: which will then reflect back any parameters sent:
Mapping A Multi-Value Parameter
- A single @RequestParamcan have multiple values: And Spring MVC will map a comma-delimited id parameter: or a list of separate id parameters:
Conclusion
- In this article, we learned how to use @RequestParam. The full source code for the examples can be found in the GitHub project.