How to Validate Keys in API in Rest Assured

 

To validate that a JSON response body contains a specific key using hasKey() from Hamcrest Matchers in Rest Assured, follow this step-by-step guide using the endpoint:

URL: https://reqres.in/api/users?page=2
Goal: Validate that the JSON response has a key like "page", "data", etc.

Code Example in Java (Rest Assured + Hamcrest hasKey())

import io.restassured.RestAssured;
import io.restassured.response.Response;
import static io.restassured.RestAssured.*;
import static org.hamcrest.Matchers.*;

public class HasKeyExample {
    public static void main(String[] args) {
        RestAssured.baseURI = "https://reqres.in";

        given()
        .when()
            .get("/api/users?page=2")
        .then()
            .statusCode(200)
            .body("$", hasKey("page"))          // top-level key
            .body("$", hasKey("per_page"))      // another top-level key
            .body("$", hasKey("data"))          // array of users
            .body("support", hasKey("url"))     // nested key inside "support"
            .body("support", hasKey("text"));   // another nested key
    }
}

Explanation:

• "$" refers to the root of the JSON response.

• hasKey("keyName") checks if a key exists at that JSON level.

• body("support", hasKey("url")) checks if the support object has a url key.

Sample Response from https://reqres.in/api/users?page=2







{
    "page": 2,
    "per_page": 6,
    "total": 12,
    "total_pages": 2,
    "data": [...],
    "support": {
        "url": "https://reqres.in/#support-heading",
        "text": "To keep ReqRes free, contributions towards server costs are appreciated!"
    }
}

Maven Dependencies

<dependency>
    <groupId>io.rest-assured</groupId>
    <artifactId>rest-assured</artifactId>
    <version>5.3.0</version>
    <scope>test</scope>
</dependency>
<dependency>
    <groupId>org.hamcrest</groupId>
    <artifactId>hamcrest</artifactId>
    <version>2.2</version>
</dependency>