Differences Betwixt @Requestparam As Well As @Pathvariable Annotations Inward Jump Mvc?

The Spring MVC framework, ane of the most pop frameworks for developing a spider web application inwards Java basis too provides several useful annotations to extract information from the incoming asking in addition to mapping the asking to controller e.g. @RequestMapping, @RequestParam, in addition to @PathVariable. Even though both @RequestParam and @ParthVariable is used to extract values from the HTTP request, in that location is a subtle departure betwixt them, which makes them a useful enquiry from an interview in addition to spring certification betoken of view. We'll seek the subtle departure between @RequestParam in addition to @PathVaraible inwards this article. As the bring upwards suggests @RequestParam is used to acquire the asking parameters from URL, too known equally query parameters, piece @PathVariable extracts values from URI.

For example, if the incoming HTTP asking to squall back a majority on topic "Java" is http://localhost:8080/shop/order/1001/receipts?date=12-05-2019, in addition to therefore yous tin work the @RequestParam annotation to squall back the query parameter date in addition to yous tin work @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 last optional but the URL must induce 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 in addition to RESTful spider web services inwards Java. It provides several ways to squall back information from the incoming HTTP requests e.g.

• Request Parameters
• Path Variables
• Form inputs

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

Using @RequestParam to acquire Query parameters

In a Spring MVC application, yous tin work the @RequestParam annotation to convey query parameters inwards Controller's handler methods.

For examples, suppose yous induce got a spider web application which returns details of orders in addition to trades in addition to yous induce got next URLs:

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

To convey the query parameters inwards the higher upwards URLs, you tin work 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 bring upwards of the query parameter is same equally the bring upwards of the variable inwards handler's @RequestParam annotated declaration in addition to therefore yous tin merely work @RequestParam without specifying the bring upwards of a query parameter, Spring volition automatically derive the value (see REST URIs contains values e.g. a REST API to squall back a majority using ISBN lay out looks similar following:

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

Now, to extract the value of ISBN lay out from the URI inwards your Spring MVC Controller's handler method, yous tin work @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 too tin too omit the value attribute inwards @PathVariable annotation, if the bring upwards of path variable's placeholder inwards the @RequestMapping annotation is same to the variable bring upwards inwards the handler method's @PathVariable annotated parameter (see REST amongst Spring).

For example, yous tin rewrite higher upwards 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 in addition to extract information from HTTP asking in addition to equally Spring developer, yous should last aware of these e.g. @RequestMapping, @RequestParam, in addition to @PathVariable.

These concepts in addition to annotations are real of import from both Spring MVC interview prospect equally good equally Spring certifications. You volition e'er honour a yoke of questions based upon these concepts.

Btw, if yous are preparing for Spring Web Certifications, yous tin too depository fiscal establishment fit out David Mayer's gratuitous Spring Mock Questions to acquire an thought close the marking of questions in addition to format of questions yous tin hold back on existent Spring Web Certification.

Difference betwixt @PathVariable in addition to @RequestParam inwards Spring

Now that nosotros empathize both the departure equally good equally how to work both @RequestParam in addition to @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 piece @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 piece @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 lay out is purpose of URI.

If yous desire to larn to a greater extent than close 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 written report which volition instruct yous the nitty-gritty of developing both REST API in addition to services for real-world scenarios.

Eugen has extensive experienced inwards developing RESTful spider web services using Spring in addition to this course of written report is a swell agency to tap into his knowledge.

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

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


That's all close the difference betwixt @PathVariable in addition to @RequestParam in Spring MVC. Even though both are used to extract information from URL, @RequestParam is used to squall back query parameters, anything afterward ? inwards the URL, piece @PathVariable is used to squall back 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, therefore yous must pass approximately fourth dimension to empathize 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 in addition to @Controller inwards Spring MVC?
How Spring MVC industrial plant internally?
What is the work of DispatcherServlet inwards Spring MVC?
How to enable Spring safety inwards a Java spider web application?
Spring inwards Action past times Craig Walls

Thanks for reading this article therefore far. If yous similar this article in addition to therefore delight portion amongst your friends in addition to colleagues. If yous induce got whatsoever questions, delight drib me a note. 

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