# Spring API input parameters

Paul Tomoiu

●

Examples,

Spring Boot,

API,

REST

●

Published 2022-12-03

This tutorial explains to you the input parameter types we can use in a Spring API.

In a Spring API, the request is received by the Controller. It can handle 3 input parameter types:

PathVariable : extracts a value from URL, but before "?" sign
RequestParam : extracts a value from URL, but after "?" sign
RequestBody : maps the content of the body request to a variable

If we have an HTTP incoming request http://domain.com:8080/employee/10?name=John we can have:

@PathVariable : to extract the department number (i.e. "10") from the URL
@RequestParam annotation to retrieve the query parameter name

Info

URL parameters or query strings are the part of a URL that typically comes after a question mark (?) and are used to pass data along with the URL.

In order to test how all those work, you can add a Controller class to a Spring Boot Application. You can use the following EmployeeController for testing:

package com.example.restdemo.employee;

import org.springframework.web.bind.annotation.*;

@RestController
public class EmployeeController {

    @GetMapping("/employee/{deptNumber}")
    String getDeptNo(@PathVariable String deptNumber) {
        return deptNumber;
    }

    @GetMapping("/employee")
    String getEmpId(@RequestParam String id, @RequestParam(required = false) String name) {
        return id+"/"+name;
    }

    @PostMapping(value="/employee", consumes = "application/json")
    String getEmployees(@RequestBody Employee newEmployee) {

        return newEmployee.getId();
    }

}

Info

In the POST method, you can see how the JSON request body is converted into an Employee object.
The JSON request body could be like this:

{"id": "200",
"name": "Brown",
"department":"20",
"age":30}

For having the example working we need to have the Employee class created as well:

package com.example.restdemo.employee;

public class Employee {
private String id;
private String name;
private String department;
private int age;

    public Employee(String id, String name, String department, int age) {
        this.id = id;
        this.name = name;
        this.department = department;
        this.age = age;
    }

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getDepartment() {
        return department;
    }

    public void setDepartment(String department) {
        this.department = department;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }
    
}