Swagger

Overview

Elide supports the generation of Swagger documentation from Elide annotated beans. Specifically, it generates a JSON document conforming to the swagger specification that can be used by tools like Swagger UI (among others) to explore, understand, and compose queries against your Elide API.

Only JSON-API endpoints are documented. The GraphQL API schema can be explored directly with tools like Graphiql.

Features Supported

  • JaxRS Endpoint - Elide ships with a customizable JaxRS endpoint that can publish one or more swagger documents.
  • Path Discovery - Given a set of entities to explore, Elide will generate the minimum, cycle-free, de-duplicated set of URL paths in the swagger document.
  • Filter by Primitive Attributes - All GET requests on entity collections include filter parameters for each primitive attribute.
  • Prune Fields - All GET requests support JSON-API sparse fields query parameter.
  • Include Top Level Relationships - All GET requests support the ability to include direct relationships.
  • Sort by Attribute - All GET requests support sort query parameters.
  • Pagination - All GET requests support pagination query parameters.
  • Permission Exposition - Elide permissions are exported as documentation for entity schemas.
  • Attribute Properties - The required, readOnly, example and value fields are extracted from ApiModelProperty annotations.

Getting Started

Maven

Pull in the following elide dependencies :

<dependency>
  <groupId>com.yahoo.elide</groupId>
  <artifactId>elide-swagger</artifactId>
</dependency>

<dependency>
  <groupId>com.yahoo.elide</groupId>
  <artifactId>elide-core</artifactId>
</dependency>

Pull in swagger core :

<dependency>
  <groupId>io.swagger</groupId>
  <artifactId>swagger-core</artifactId>
</dependency>

Elide Standalone Setup

If you are using Elide Standalone, you can extend ElideStandaloneSettings to configure swagger. The enableSwagger function returns a map of Swagger documents keyed by a name for each document that will be exposed in the swagger document URL.

    @Override
    public Map<String, Swagger> enableSwagger() {

        //Create a dictionary of the entities that will be exposed in swagger
        EntityDictionary dictionary = new EntityDictionary(new HashMap());
        dictionary.bindEntity(ArtifactGroup.class);
        dictionary.bindEntity(ArtifactProduct.class);
        dictionary.bindEntity(ArtifactVersion.class);

        //Title and version your service
        Info info = new Info().title("Test Service").version("1.0");

        //Build the swagger document with the base API path
        SwaggerBuilder builder = new SwaggerBuilder(dictionary, info);
        Swagger swagger = builder.build().basePath("/api/v1");

        //Return the map of swagger documents
        Map<String, Swagger> docs = new HashMap<>();
        docs.put("test", swagger);
        return docs;
    }

The code above exposes a single swagger document at the URL /swagger/doc/test. To change the path where swagger will be exposed, override this function in ElideStandaloneSettings:

    @Override
    public String getSwaggerPathSepc() {
        return "/mySwaggerPath/*";
    }

Basic Setup

If you are using Elide directly as a library (and not using Elide Standalone), follow these instructions:

Create and initialize an entity dictionary.

EntityDictionary dictionary = new EntityDictionary(Maps.newHashMap());

dictionary.bindEntity(Book.class);
dictionary.bindEntity(Author.class);
dictionary.bindEntity(Publisher.class);

Create a swagger info object.

Info info = new Info().title("My Service").version("1.0");

Initialize a swagger builder.

SwaggerBuilder builder = new SwaggerBuilder(dictionary, info);

Build the swagger document

Swagger document = builder.build();

Convert Swagger to JSON

You can directly convert to JSON:

String jsonOutput = SwaggerBuilder.getDocument(document);

Configure JAX-RS Endpoint

Or you can use the Swagger document directly to configure the provided JAX-RS Endpoint:

Map<String, Swagger> swaggerDocs = new HashMap<>();
docs.put("publishingModels", document)

//Dependency Inject the DocEndpoint JAX-RS resource
bind(docs).named("swagger").to(new TypeLiteral<Map<String, Swagger>>() { });

Supporting OAuth

If you want swagger UI to acquire & use a bearer token from an OAuth identity provider, you can configure the swagger document similar to:

SecuritySchemeDefinition oauthDef = new OAuth2Definition().implicit(CONFIG_DATA.zuulAuthorizeUri());
SecurityRequirement oauthReq = new SecurityRequirement().requirement("myOauth");

SwaggerBuilder builder = new SwaggerBuilder(entityDictionary, info);
Swagger document = builder.build();
    .basePath("/my/url/path")
    .securityDefinition("myOauth", oauthDef)
    .security(oauthReq)
    .scheme(Scheme.HTTPS));

Adding a global parameter

A query or header parameter can be added globally to all Elide API endpoints:

HeaderParameter oauthParam = new HeaderParameter()
    .name("Authorization")
    .type("string")
    .description("OAuth bearer token")
    .required(false);

SwaggerBuilder crashBuilder = new SwaggerBuilder(dictionary, info)
    .withGlobalParameter(oauthParam);

Adding a global response code

An HTTP response can be added globally to all Elide API endpoints:

Response rateLimitedResponse = new Response().description("Too Many Requests");

SwaggerBuilder crashBuilder = new SwaggerBuilder(dictionary, info)
    .withGlobalResponse(429, rateLimitedResponse);

Performance

Path Generation

The Swagger UI is very slow when the number of generated URL paths exceeds a few dozen. For large, complex data models, it is recommended to generate separate swagger documents for subgraphs of the model.

Set<Class<?>> entities = Sets.newHashSet(
    Book.class,
    Author.class,
    Publisher.class
);
 
SwaggerBuilder coreBuilder = new SwaggerBuilder(dictionary, info)
    .withExplicitClassList(entities);

In the above example, swagger will only generate paths that exclusively traverse the provided set of entities.

Document Size

The size of the swagger document can be reduced significantly by limiting the number of filter operators that are used to generate query parameter documentation.

SwaggerBuilder crashBuilder = new SwaggerBuilder(dictionary, info)
   .withFilterOps(Sets.newHashSet(Operator.IN));

In the above example, filter query parameters are only generated for the IN operator.

Attribute Properties

Elide extracts properties from the ApiModelProperty annotation and adds them to the swagger documentation.

class Book {

    @ApiModelProperty(required = true)
    public String title;
}

Only the required, value, example, and readOnly properties are extracted. This is currently only supported for attributes on Elide models.