SPRING BOOT @PutMapping
SPRING BOOT
The @PutMapping annotation is typically used to update existing resources on the server using the HTTP PUT method.
Spring Boot @PutMapping annotation
➔ @PutMapping is a Spring Boot annotation used to map an HTTP PUT request to a specific handler method in a Spring Boot controller class.
Key characteristics and usage of @PutMapping annotation:
➔ The handler method receives data from the client and checks whether the entity or data already exists.
➔ @PutMapping can be used by implementations to create a resource, if it does not already exist.
➔ This annotation performs the standard operation of updating existing entities and passing this updated entity or model to the service layer.
➔ When data is received from the client in JSON or XML format, @RequestBody automatically deserializes it into a Java object.
➔ @PutMapping is an alternative to @RequestMapping(method = RequestMethod.POST) because both annotations perform the same function, either of them can be used, but @PutMapping is recommended.
➔ A single method can serve multiple URLs using a string array in the value or path attribute, for example, @PutMapping(path={"/update","/edit"}).
Syntax
/* all are equivalent. */
@PutMapping({"/update", "/edit"}) or
@PutMapping(value={"/update", "/edit"}) or
@PutMapping(path={"/update", "/edit"})
➔ The value and path attributes of the @PutMapping annotation are aliases for each other and can be used interchangeably.
Syntax
/* All are equivalent. */
@PutMapping("/edit") or
@PutMapping(value = "/edit") or
@PutMapping(path = "/edit")
@PutMapping supports attributes to match the requested url
➔ params: Narrowing mappings based on the request parameters.
Syntax
Example: @PutMapping(value = "/update", params = "name")
➔ headers: Narrowing mappings based on the specific header values.
Syntax
Example: @PutMapping(value = "/update", headers="name=john")
➔ consumes: This specifies that the media type can be consumed or received by the controller method (e.g., consumes = "application/json").
➔ produces: This specifies that the media type should be produced by the controller method (e.g., produces = "application/json").
Syntax
Example: @PutMapping(value = "/update", produces="application/xml")
Example: @PutMapping(value = "/update", produces = MediaType.APPLICATION_JSON_VALUE)
Example: @PutMapping(value = "/update", produces = {"application/json", "application/xml"})
@PutMapping handles dynamic URLs using @PathVariable.
➔ For example, @PutMapping("/update/{id}") can work with handlerName(@PathVariable Long id) to handle dynamic URLs.
Request URL is localhost:8090/update/101
Syntax
@PutMapping(value="/update/{id}")
public String updateHandler(@PathVariable Long id) {
return "PathVariable is working fine, ID="+id;
}
@PutMapping handles request parameters using @RequestParam.
➔ For example, @PutMapping(/update) can work with handlerName(@RequestParam(name = "name") String name) to handle query parameters.
➔ Parameters can be sent as a query string in the URL or as form data in the body of the HTTP request.
The request URL is localhost:8090/update?name=john
Syntax
@PutMapping(value="/update")
public String updateHandler(@RequestParam("name") String n) {
return "RequestParam is working fine, name="+n;
}
Common usage and best practices:
➔ @PutMapping typically accepts data such as a String, a Java object, or a list of Java objects using the @RequestBody annotation, which Spring Boot automatically converts this incoming data (usually JSON or XML) into the appropriate Java format.
➔ @PutMapping typically returns data such as a String, a Java object, or a list of Java objects, which Spring Boot automatically converts to the appropriate response format.
Now practice this chapter in your learning environment.
01 Create a Spring Boot project using Spring Tool Suite (STS).
02 Create a Controller class
Name it anything, for example UsersController.
Controller Code
package com.exam.helloworld;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.PutMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class UsersController {
@PostMapping("/add/{id}")
public String addHandler(@RequestBody String data, @PathVariable Long id, @RequestParam String name) {
return "Data is: " + data + "\nPathVariable is: " + id + "\nRequestParam is: " + name;
}
@PutMapping("/update")
public String updateHandler(@RequestBody String data) {
return "Data is: " + data;
}
}
03 Run HelloworldApplication.java
After successfully run the application.
Now test the @PutMapping request url in Postman (an API testing tool).
Send JSON object.
Send JavaScript object.
JSON and JavaScript object data types.
JSON Data types:
In JSON, keys must be enclosed in double quotes, and single quotes are not allowed.
Values can be enclosed in double quotes or without any quotes, depending on their data type and content. for example {"name": "Maria", "age": 22}. Single quotes are not allowed.
➔ String: The value must be enclosed in double quotes for example "John Doe".
➔ Number: An integer or floating-point number.
➔ Boolean: true or false.
➔ null: An empty value (null).
➔ Object: A collection of key-value pairs enclosed in curly braces {} and the Keys must be strings.
➔ Array: A list of values enclosed in square brackets [].
JavaScript Object Data Types:
The key can be enclosed in single quotes, double quotes or identifire without qoute. for example 'name', "name", name.
Values can be enclosed in double quotes, single quotes, or without any quotes, depending on their data type and content.
➔ All json type such as Strings, numbers, booleans, null, objects, and arrays.
➔ undefined: A variable has been declared but its value has not been assigned.
➔ BigInt: Beyond the standard number limit.
➔ Function: A method within the object.
➔ Built-in object types: Such as Date, Map, Set, RegExp, etc.
Send Text data.
Example @PathVariable
package com.exam.helloworld;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.PutMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class UsersController {
@PutMapping("/update/{id}")
public String updateHandler(@RequestBody String data, @PathVariable Long id) {
return "Data is: " + data+ "\nPathVariable is: " + id ;
}
}
@PathVariable with @PutMapping, output
Example @RequestParam
package com.exam.helloworld;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.PutMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class UsersController {
@PutMapping("/update/{id}")
public String updateHandler(@RequestBody String data, @PathVariable Long id, @RequestParam String name) {
return "Data is: " + data+ "\nPathVariable is: " + id + "\nRequestParam is: " + name;
}
}
@RequestParam with @PutMapping, output
