Spring: openAPI: Refer external documentation

Using @ ExternalDocumentation, we can refer external documentation. @ExternalDocumentation annotaiton can be applied at method level or as field of Operation to add a reference to an external resource for extended documentation.

 

Example

@Operation(summary = "Get the employee details by name", externalDocs = @ExternalDocumentation(url = "https://self-learning-java-tutorial.blogspot.com/2019/08/spring-boot-rest-requestparam-access.html"))
@GetMapping("/by-name")
public ResponseEntity<Map<String, Object>> infoByName(
                @Parameter(name = "firstName", in = ParameterIn.QUERY, description = "firstName ex: krishna", required = true) @RequestParam(name = "firstName", required = false) String firstName,
                @Parameter(name = "lastName", in = ParameterIn.QUERY, description = "lastName ex: krishna", required = true) @RequestParam(name = "lastName", required = false) String lastName) {
        ........
        ........
}

Above snippet generate documentation url in the swagger documentation like below.

 

Find the below working application.

 

Step 1: Create new maven project ‘openapi-refer-external-documentaion’.

 

Step 2: Update pom.xml with maven dependencies.

 

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
        <modelVersion>4.0.0</modelVersion>
        <groupId>com.sample.app</groupId>
        <artifactId>openapi-refer-external-documentaion</artifactId>
        <version>1</version>

        <parent>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-parent</artifactId>
                <version>2.6.4</version>
        </parent>


        <properties>
                <java.version>1.8</java.version>
                <maven.compiler.source>${java.version}</maven.compiler.source>
                <maven.compiler.target>${java.version}</maven.compiler.target>
                <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
                <project.report.outputEncoding>UTF-8</project.report.outputEncoding>
        </properties>
        
        <dependencies>
                <dependency>
                        <groupId>org.springframework.boot</groupId>
                        <artifactId>spring-boot-starter-web</artifactId>
                </dependency>


                <dependency>
                        <groupId>org.springdoc</groupId>
                        <artifactId>springdoc-openapi-ui</artifactId>
                        <version>1.6.6</version>
                </dependency>


        </dependencies>
</project>

Step 3: Define UserController class.

 

UserController.java

package com.sample.app.controller;

import java.util.HashMap;
import java.util.Map;

import io.swagger.v3.oas.annotations.ExternalDocumentation;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.CrossOrigin;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

import io.swagger.v3.oas.annotations.Operation;
import io.swagger.v3.oas.annotations.Parameter;
import io.swagger.v3.oas.annotations.enums.ParameterIn;

@RestController
@RequestMapping(value = "/api/v1/users")
@CrossOrigin("*")
public class UserController {

        @Operation(summary = "Get the employee details by name", externalDocs = @ExternalDocumentation(url = "https://self-learning-java-tutorial.blogspot.com/2019/08/spring-boot-rest-requestparam-access.html"))
        @GetMapping("/by-name")
        public ResponseEntity<Map<String, Object>> infoByName(
                        @Parameter(name = "firstName", in = ParameterIn.QUERY, description = "firstName ex: krishna", required = true) @RequestParam(name = "firstName", required = false) String firstName,
                        @Parameter(name = "lastName", in = ParameterIn.QUERY, description = "lastName ex: krishna", required = true) @RequestParam(name = "lastName", required = false) String lastName) {

                Map<String, Object> myDetails = new HashMap<>();

                if (firstName != null) {
                        myDetails.put("firstName", firstName);
                }

                if (lastName != null) {
                        myDetails.put("lastName", lastName);
                }

                return ResponseEntity.ok(myDetails);

        }

}

Step 4: Define main application class.

 

App.java

package com.sample.app;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class App {
        public static void main(String[] args) {

                SpringApplication.run(App.class, args);

        }
}

Total project structure looks like below.

Run App.java.

 

Open the url ‘http://localhost:8080/swagger-ui/index.html’ to experiment with swagger documentation.

 

You can download the complete working application from this link.

   

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