Differences Betwixt @Requestparam Together With @Pathvariable Annotations Inwards Jump Mvc?

The Spring MVC framework, i of the most pop frameworks for developing a spider web application inwards Java globe besides provides several useful annotations to extract information from the incoming asking as well as mapping the asking to controller e.g. @RequestMapping, @RequestParam, as well as @PathVariable. Even though both @RequestParam and @ParthVariable is used to extract values from the HTTP request, at that spot is a subtle departure betwixt them, which makes them a useful query from an interview as well as spring certification indicate of view. We'll seek out the subtle departure between @RequestParam as well as @PathVaraible inwards this article. As the lift suggests @RequestParam is used to acquire the asking parameters from URL, besides known equally query parameters, land @PathVariable extracts values from URI.

For example, if the incoming HTTP asking to think a majority on theme "Java" is http://localhost:8080/shop/order/1001/receipts?date=12-05-2017, as well as then yous tin piece of employment the @RequestParam annotation to think the query parameter date as well as yous tin piece of employment @PathVariable to extract the orderId i.e. "1001" equally shown below:

@RequestMapping(value="/order/{orderId}/receipts", method = RequestMethod.GET)
public List listUsersInvoices(                               @PathVariable("orderId") int order,
 @RequestParam(value = "date", required = false) Date dateOrNull) {
...
}

The required=false denotes that query parameter tin travel optional but the URL must cause got the same URI.

How to extract Query Parameters inwards Spring MVC using @RequestParam

Spring MVC is a rich framework to educate both spider web applications as well as RESTful spider web services inwards Java. It provides several ways to think information from the incoming HTTP requests e.g.

• Request Parameters
• Path Variables
• Form inputs

Now that yous know the departure betwixt @RequestParam as well as @PathVariable inwards Spring MVC, let's meet how to write Spring controllers that tin grip asking parameters as well as path variables.

Using @RequestParam to acquire Query parameters

In a Spring MVC application, yous tin piece of employment the @RequestParam annotation to bring query parameters inwards Controller's handler methods.

For examples, suppose yous cause got a spider web application which returns details of orders as well as trades as well as yous cause got next URLs:

http://localhost:8080/eportal/orders?id=1001

To bring the query parameters inwards the to a higher house URLs, you tin piece of employment the next code inwards the Spring MVC controller:

@RequestMapping("/orders")
public String showOrderDetails(@RequestParam("id") String orderId, Model model){
   model.addAttribute("orderId", orderId);
   return "orderDetails";
}


If the lift of the query parameter is same equally the lift of the variable inwards handler's @RequestParam annotated declaration as well as then yous tin but piece of employment @RequestParam without specifying the lift of a query parameter, Spring volition automatically derive the value (see REST URIs contains values e.g. a REST API to think a majority using ISBN unwrap looks similar following:

URL: http://localhost:8080/book/9783827319333

Now, to extract the value of ISBN unwrap from the URI inwards your Spring MVC Controller's handler method, yous tin piece of employment @PathVariable annotation equally shown inwards next code:

@RequestMapping(value="/book/{ISBN}", method= RequestMethod.GET)
public String showBookDetails(@PathVariable("ISBN") String id,
                              Model model){
   model.addAttribute("ISBN", id);
   return "bookDetails";
}

Similar to @RequestParameter annotation, yous besides tin besides omit the value attribute inwards @PathVariable annotation, if the lift of path variable's placeholder inwards the @RequestMapping annotation is same to the variable lift inwards the handler method's @PathVariable annotated parameter (see REST amongst Spring).

For example, yous tin rewrite to a higher house code equally shown below:

@RequestMapping(value="/book/{ISBN}", method= RequestMethod.GET)
public String showBookDetails(@PathVariable String ISBN, 
                              Model model){
   model.addAttribute("ISBN", ISBN);
   return "bookDetails";
}


Spring MVC provides several useful annotations to map as well as extract information from HTTP asking as well as equally Spring developer, yous should travel aware of these e.g. @RequestMapping, @RequestParam, as well as @PathVariable.

These concepts as well as annotations are real of import from both Spring MVC interview prospect equally good equally Spring certifications. You volition ever detect a couplet of questions based upon these concepts.

Btw, if yous are preparing for Spring Web Certifications, yous tin besides banking enterprise tally out David Mayer's gratis Spring Mock Questions to acquire an thought near the marking of questions as well as format of questions yous tin aspect on existent Spring Web Certification.

Difference betwixt @PathVariable as well as @RequestParam inwards Spring

Now that nosotros sympathize both the departure equally good equally how to piece of employment both @RequestParam as well as @PathVariable inwards Spring MVC application, let's revise the fundamental departure betwixt them from an interview perspective.

1) The @RequestParam is used to extract query parameters land @PathVariable is used to extract information correct from the URI.

2) @RequestParam is to a greater extent than useful on a traditional spider web application where information is generally passed inwards the query abatements land @PathVariable is to a greater extent than suitable for RESTful spider web services where URL contains values e.g. http://localhost:8080/book/9783827319333, hither data, which is ISBN unwrap is business office of URI.

If yous desire to larn to a greater extent than near how to effectively educate REST applications using Spring, I advise yous bring together Eugen Paraschiv's REST amongst Spring course.

It's an online course of report which volition instruct yous the nitty-gritty of developing both REST API as well as services for real-world scenarios.

Eugen has extensive experienced inwards developing RESTful spider web services using Spring as well as this course of report is a groovy means to tap into his knowledge.

3) @RequestParam annotation tin specify default values if a query parameter is non introduce or empty yesteryear using a defaultValue attribute, provided the required attribute is false.

4) Spring MVC allows yous to piece of employment multiple @PathVariable annotations inwards the same method, provided, no to a greater extent than than i declaration has the same pattern.


That's all near the difference betwixt @PathVariable as well as @RequestParam in Spring MVC. Even though both are used to extract information from URL, @RequestParam is used to think query parameters, anything afterward ? inwards the URL, land @PathVariable is used to think values from URI itself.  This concept is real of import for both traditional spider web application evolution equally good equally developing RESTful Web Services using Spring, thence yous must pass around fourth dimension to sympathize it better.

Other Spring MVC articles yous may similar to explore
Spring Framework 5: Beginner to Guru
Spring MasterClass from Beginner to Expert
Difference between @RestController as well as @Controller inwards Spring MVC?
How Spring MVC plant internally?
What is the piece of employment of DispatcherServlet inwards Spring MVC?
How to enable Spring safety inwards a Java spider web application?
Spring inwards Action yesteryear Craig Walls

Thanks for reading this article thence far. If yous similar this article as well as then delight part amongst your friends as well as colleagues. If yous cause got whatever questions, delight driblet me a note. 

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