Please read part II at https://dzone.com/articles/doing-more-with-springdoc-openapi.. Also, please read part III at https://dzone.com/articles/extending-swagger-and-spring-doc-open-api. Press the Try it out button. Finally, let's write the spring boot application class. We will be designing an API for a record label.
This was about 130 lines of specification, and the spec will only get longer as the API gets bigger. What we have just described are just 2 endpoints and 3 actions. We will define the /artists endpoint and the GET method for this endpoint. "http://www.w3.org/2001/XMLSchema-instance", "http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd", logging.level.org.springframework.boot.autoconfigure, https://spring.io/guides/gs/rest-service/, https://github.com/teq-niq/sample/tree/springdoc-openapi-intro, https://dzone.com/articles/doing-more-with-springdoc-openapi, https://dzone.com/articles/extending-swagger-and-spring-doc-open-api, 7 Reasons to Choose Apache Pulsar over Apache Kafka, Building an IoT Security Camera With Raspberry Pi and Render, Stop Using OAuth 2.0 Scopes for Microservices Authorization. Query parameters are the most common type of parameters. OpenAPI Specification (formerly known as Swagger Specification) is an open-source format for describing and documenting APIs. Also note how the API version and description is being leveraged from application.properties. The latest version of OpenAPI is 3.0. The path parameters can be used to isolate a specific component of the data that the client is working with, for example, https://example.io/v1/artists/{username}. You can find more information about HTTP status codes here. Path parameters are part of the hierarchical component of the URL, and are thus stacked sequentially.
At this stage, this is what the project looks like in Eclipse: Above are the project contents. OpenAPI 3.0 is an open-source format for describing and documenting APIs. So, a client will use GET https://example.io/v1/artists to get a list of artists. All Rights Reserved. Below, you will see the pom.xml to use: Note the "springdoc-openapi-ui" dependency and "springdoc-openapi-maven-plugin" plugin. One of the things you may notice in the spec we have so far is that we have the same Artist schema (artist name, genre, username and albums published) that gets repeated in various 200 and 400 responses. In this tutorial, we are going to try out a Spring Boot Open API 3-enabled REST project and explore some of its capabilities. The GET method, under the artists endpoint, lets the consumer of the API obtain the details of a list of artists from the https://example.io/v1 database. Here is how we can use components to store the schema for an HTTP 200 OK response. A simple OpenAPI 3.0 specification looks like this: The syntax above will make sense once we finish this walkthrough. SwaggerHub is free with loads of features to get you started quickly, so give it a try! The OpenAPI Specification has a solution reusable components that can be used across multiple endpoints in the same API.
This is an example of a Java bean. In the Swagger UI, if you are unable to access the Schema definitions link, it might be because you need to come out of the try it out mode. In our example, it would make sense to let the client limit the information required instead of returning the entire list of artists from the database, which would lead to unnecessary load on the server. Here, we have specified the username as a path parameter. If you want to become an OpenAPI expert, you can refer to the full OpenAPI 3.0 specification and to the how-to guide, or try out our certification courses! Bigger APIs would involve rewriting and reusing a lot of the same specs, so it would be a tedious task writing a more complex API. The spec is not only shorter, but anytime a new endpoint with the same schema is needed, the designer does not need to spend time writing the piece. The servers array specifies one or more server URLs for API calls. Path parameters (username in this case) have to be mandatorily described in the parameters object under the method. In our example, the server URL is https://example.io/v1. OpenAPI definitions can be written in JSON or YAML. We have successfully designed a RESTful API which exposes the artists present in the database of a record label! Let's make some entries in src\main\resources\application.properties. Join the DZone community and get the full member experience. We are going to refer to https://spring.io/guides/gs/rest-service/ and https://springdoc.org/. An API defined using the OpenAPI Specification can be divided into 3 main sections . Then, execute java -jar target\sample-0.0.1.jar. The components section also has subsections for storing reusable parameters and responses. We also define a reusable 400Error response, which we then reference from all the endpoints. Now, let's create a controller.
You can also launch the application by running the SampleApplication.java class from your IDE. For this API, lets add the ability for a user to post an artist to our database. A successful response will return the artist name, genre, username and albums recorded. Click on one or two Cancel buttons that might be visible. These components are defined in the global components section and then are referenced in individual endpoints. See Describing Responses for more information on responses. In this tutorial, we will write a simple API definition in the OpenAPI 3.0 format. The nice thing is how the contract is automatically detailed leveraging JSR-303 annotations on the model. Lets create a new endpoint which returns a specific artists information based on the username provided. The above entries will pass on Maven build-related information to the OpenAPI documentation. If using the Eclipse IDE, we might need to do a Maven update on the project after creating all the files. An unsuccessful request is described under the 400 HTTP code, with a corresponding error message detailing why the response is invalid. Start by creating a Maven JAR project. The path parameter here would be the username of the artist whose info we need. Lets start with a simple API definition that contains just meta information, such as the API title, version, server URL and other descriptive information. The thing to note is that path parameters have to have a true property set to the required parameter, for the spec to be valid. You have just designed a simple API for a record label! These endpoints are relative to the server URL, which in our example is https://example.io/v1. Over 2 million developers have joined DZone. Our API definition already had the components section containing securitySchemes, now we have moved components to the bottom and added the schemas subsection. Each API definition starts with the version of the OpenAPI Specification that this definition uses. Next, execute the mvn clean package from the command prompt or terminal. If you are using OpenAPI 2.0 (Swagger 2.0), see this tutorial instead. Let's feed that valid input into the Request Body Section. The info object contains the API title and version, which are required, and an optional description. However, I did not see it support out of the box @javax.validation.constraints.Email and @org.hibernate.validator.constraints.CreditCardNumber at this point in time. The request body is defined by using the requestBody object. Some APIs have a single server, others may have multiple servers, such as production and sandbox. We recommend using SwaggerHubs built-in editor and validator to quickly write and visualize the OpenAPI definition described in this tutorial. It is a non-hierarchical component of the URL. The Specification was originally developed in 2010 by Reverb Technologies (formerly Wordnik) as a way to keep the API design and documentation in sync. Query parameters are optional and non unique, so they can be specified multiple times in the URL. The API endpoint paths are appended to the server URL. In the spec below, we define the reusable query parameters offset and limit and then reference them in the /artists endpoint. We have only covered the basics of OpenAPI, as the specification can be anything you want it to be (mostly). Every response would need at least one HTTP status code to describe the kind of responses a consumer is likely to expect. We recommend YAML, because it is easier to read and write. The Specification defines various types of reusable components: The schemas subsection of the global components section can contain various data models consumed and returned by the API. POST, PUT and PATCH requests typically contain the request body. The path items are the endpoints of your API under which you can specify HTTP verbs for manipulating the resources in the desired manner. RESTful parameters specify the variable part of the resource a user works with.
To jump to a definition, simply click the $ref link. See here for more information about components. In this tutorial, we will guide you through building a simple API while covering all the important aspects of the OpenAPI Specification. The description gives details on what the responses of the API would be.
If you followed through till here, then congratulation!
On pressing the blue Execute button we see the below: This was only a brief introduction to the capabilities of the dependency: Source Code is here: https://github.com/teq-niq/sample/tree/springdoc-openapi-intro.Git Clone URL: https://github.com/teq-niq/sample.git.Branch: springdoc-openapi-intro. They appear at the end of a URL following a question mark. Thus, the specification would now look as follows . It out-of-the-box covers many of the important annotations and documents them. Now, let's create a small Java bean class. The client could describe the page number (offset) and the amount of information on the page (limit), for example: These variables are defined under the parameters object in the OpenAPI definition. Join the TestComplete Introductory Training on March 22, Calling Zephyr Scale users to contribute to the product and community, Number of albums published under the label. For more advanced security, see Authentication. 2021 SmartBear Software. Springdoc-openapi java library is fast becoming very compelling. In our example, it is openapi: 3.0.0. Opinions expressed by DZone contributors are their own. Lets assume that the record label has a database of artists with the following information: The API will let consumers obtain the list of artists stored in the database and add a new artist to the database. This would be under the /artists resource. We also secure the API using Basic authentication, so that only authorized users can consume the API. If you want to get some advanced information on parameters, see Describing Parameters. It has since become a de-facto standard for designing and describing RESTful APIs, and is used by millions of developers and organizations for developing their APIs, be it internal or client facing. For completeness, let's post a request. In our sample code, we have specified 200, which is a successful client request, while 400 is an unsuccessful request. Now, let's visit the Swagger UI http://localhost:8080/swagger-ui.html: Click the green Post button and expand the > symbol on the right of Person under Schemas.