Spring Boot + GraphQL Tutorial - Understanding GraphQL Query

In previous tutorial we implemented Spring Boot + GraphQL Hello World Example. In this tutorial we will be implementing examples to understand GraphQL Query Language in greater detail.

Implementation

Previously we were calling the helloWorld method which used to return the hello world string. We will be modifying the Spring Boot + GraphQL example we had implemented in previous tutorial. The Maven Project will be as follows-

Passing request parameter using GraphQL

Define a method named getEmployeeName which takes the empId parameter and returns the name for the Employee.

package com.javainuse.query;

import org.springframework.stereotype.Component;
import com.javainuse.model.InputRequest;
import graphql.kickstart.tools.GraphQLQueryResolver;

@Component
public class Query implements GraphQLQueryResolver {

	public String helloWorld() {
		return "Hello World";
	}

	public String getEmployeeName(String empId) {
		return "TestEmployee for employee id " + empId;
	}
}

Next we will be defining the getEmployeeName method in the GraphQL schema -

type Query{

helloWorld : String

getEmployeeName(empId : String): String

}

Start the Spring Boot Application. If we now go to the GraphQL UI using http://localhost:8080/graphiql
We will be creating the input request as follows-

query{
  getEmployeeName(empId : "emp1")
}

Using GraphQL pass JSON object as request parameter and get JSON object as response

We will be creating a method which takes a object InputRequest and returns object of type Employee.
Create the InputRequest class as follows-

package com.javainuse.model;

public class InputRequest {
	private String empId;
	private boolean present;

	public String getEmpId() {
		return empId;
	}

	public void setEmpId(String empId) {
		this.empId = empId;
	}

	public boolean isPresent() {
		return present;
	}

	public void setPresent(boolean present) {
		this.present = present;
	}
}

Create the Employee class as follows-

package com.javainuse.model;

public class Employee {
	
	private String empId;
	private String empName;
	
	public String getEmpId() {
		return empId;
	}
	public void setEmpId(String empId) {
		this.empId = empId;
	}
	public String getEmpName() {
		return empName;
	}
	public void setEmpName(String empName) {
		this.empName = empName;
	}
}

Modify the Query class to create the method which takes the InputRequest as a method parameter and returns the Employee class-

package com.javainuse.query;

import org.springframework.stereotype.Component;

import com.javainuse.model.Employee;
import com.javainuse.model.InputRequest;

import graphql.kickstart.tools.GraphQLQueryResolver;

@Component
public class Query implements GraphQLQueryResolver {

	public String helloWorld() {
		return "Hello World";
	}

	public String getEmployeeName(String empId) {
		return "TestEmployee for employee id " + empId;
	}

	public Employee getEmployeeNameIfPresent(InputRequest inputRequest) {
		Employee emp = new Employee();
		emp.setEmpId(inputRequest.getEmpId());
		emp.setEmpName("TestEmployee");
		return emp;
	}

}

Finally modify the GraphQL schema as follows-

type Query{

helloWorld : String

getEmployeeName(empId : String): String

getEmployeeNameIfPresent(inputRequest : InputRequest): Employee

}

input InputRequest {
empId : String
present : Boolean
}

type Employee {
empId : String
empName : String
}

Start the Spring Boot Application. If we now go to the GraphQL UI using http://localhost:8080/graphiql
We will be creating the input request as follows-

query{
  getEmployeeNameIfPresent(inputRequest:{
    empId:"emp11"
    present:true    
  }) {
    empId
    empName
  }
}