= Vert.x OpenAPI
:toc: left

Vert.x OpenAPI extends Vert.x Web to support https://www.openapis.org/[OpenAPI 3], bringing to you a simple interface to build a Vert.x Web Router conforming your API contract.

Vert.x OpenAPI can:

* Parse and validate the your OpenAPI 3 contract
* Generate a router according to your spec, with correct path & methods
* Provide request parsing and validation based on your contract using https://vertx.io/docs/vertx-web-validation/java/[Vert.x Web Validation]
* Mount required security handlers
* Path conversion between OpenAPI style and Vert.x style
* Route requests to event bus using https://vertx.io/docs/vertx-web-api-service/java/[Vert.x Web API Service]

== Using Vert.x OpenAPI

To use Vert.x OpenAPI, add the following dependency to the _dependencies_ section of your build descriptor:

* Maven (in your `pom.xml`):

[source,xml,subs="+attributes"]
----
<dependency>
 <groupId>io.vertx</groupId>
 <artifactId>vertx-web-openapi</artifactId>
 <version>4.0.2</version>
</dependency>
----

* Gradle (in your `build.gradle` file):

[source,groovy,subs="+attributes"]
----
dependencies {
 compile 'io.vertx:vertx-web-openapi:4.0.2'
}
----

== `RouterBuilder`

`link:../../apidocs/io/vertx/ext/web/openapi/RouterBuilder.html[RouterBuilder]` is the main element of this module: It provides the interface to mount request handlers and generates the final `link:../../apidocs/io/vertx/ext/web/Router.html[Router]`

To start using Vert.x Web OpenAPI, you must instantiate `link:../../apidocs/io/vertx/ext/web/openapi/RouterBuilder.html[RouterBuilder]` with your contract using
`link:../../apidocs/io/vertx/ext/web/openapi/RouterBuilder.html#create-io.vertx.core.Vertx-java.lang.String-io.vertx.core.Handler-[RouterBuilder.create]`

For example to load a spec from the local filesystem:

[source,java]
----
RouterBuilder.create(vertx, "src/main/resources/petstore.yaml").onComplete(ar -> {
  if (ar.succeeded()) {
    // Spec loaded with success
    RouterBuilder routerBuilder = ar.result();
  } else {
    // Something went wrong during router builder initialization
    Throwable exception = ar.cause();
  }
});
----

You can construct a router builder from a remote spec:

[source,java]
----
RouterBuilder.create(
  vertx,
  "https://raw.githubusercontent" +
    ".com/OAI/OpenAPI-Specification/master/examples/v3.0/petstore.yaml"
).onComplete(ar -> {
  if (ar.succeeded()) {
    // Spec loaded with success
    RouterBuilder routerBuilder = ar.result();
  } else {
    // Something went wrong during router builder initialization
    Throwable exception = ar.cause();
  }
});
----

You can access a private remote spec configuring `link:../../apidocs/io/vertx/ext/web/openapi/OpenAPILoaderOptions.html[OpenAPILoaderOptions]`:

[source,java]
----
OpenAPILoaderOptions loaderOptions = new OpenAPILoaderOptions()
  .putAuthHeader("Authorization", "Bearer xx.yy.zz");
RouterBuilder.create(
  vertx,
  "https://raw.githubusercontent" +
    ".com/OAI/OpenAPI-Specification/master/examples/v3.0/petstore.yaml",
  loaderOptions
).onComplete(ar -> {
  if (ar.succeeded()) {
    // Spec loaded with success
    RouterBuilder routerBuilder = ar.result();
  } else {
    // Something went wrong during router builder initialization
    Throwable exception = ar.cause();
  }
});
----

You can modify different behaviours of the router builder with `link:../../apidocs/io/vertx/ext/web/openapi/RouterBuilderOptions.html[RouterBuilderOptions]`:

[source,java]
----
routerBuilder.setOptions(new RouterBuilderOptions());
----

== Access to operations

To access to an https://github.com/OAI/OpenAPI-Specification/blob/master/versions/3.0.1.md#operationObject[Operation] defined in contract, use `link:../../apidocs/io/vertx/ext/web/openapi/RouterBuilder.html#operation-java.lang.String-[operation]`.
This method returns an `link:../../apidocs/io/vertx/ext/web/openapi/Operation.html[Operation]` instance that you can use to both access the model and assign handlers

To mount an handler to an operation use `link:../../apidocs/io/vertx/ext/web/openapi/Operation.html#handler-io.vertx.core.Handler-[handler]`,
to mount a failure handler use `link:../../apidocs/io/vertx/ext/web/openapi/Operation.html#failureHandler-io.vertx.core.Handler-[failureHandler]`

You can **add multiple handlers to same operation**, without overwrite the existing ones.

For example:

[source,java]
----
routerBuilder
  .operation("awesomeOperation")
  .handler(routingContext -> {
    RequestParameters params =
      routingContext.get(ValidationHandler.REQUEST_CONTEXT_KEY);
    RequestParameter body = params.body();
    JsonObject jsonBody = body.getJsonObject();
    // Do something with body
  }).failureHandler(routingContext -> {
  // Handle failure
});
----

[IMPORTANT]
====
You can't access to contract operations without `operationId`. The operations without `operationId` are ignored by the `RouterBuilder`
====

Vert.x OpenAPI mounts the correct `link:../../apidocs/io/vertx/ext/web/validation/ValidationHandler.html[ValidationHandler]` for you, so you can access to request parameters and request body.
Refer to https://vertx.io/docs/vertx-web-validation/java/[Vert.x Web Validation documentation] to learn how to get request parameters & request body and how to manage validation failures

== Map `AuthenticationHandler` to OpenAPI security schemes

You can map an `link:../../apidocs/io/vertx/ext/web/handler/AuthenticationHandler.html[AuthenticationHandler]` to a security schema defined in the contract.

For example, given your contract has a security schema named `security_scheme_name`:

[source,java]
----
routerBuilder.securityHandler("security_scheme_name", authenticationHandler);
----

You can mount `link:../../apidocs/io/vertx/ext/web/handler/AuthenticationHandler.html[AuthenticationHandler]` included in Vert.x Web, for example:

[source,java]
----
routerBuilder.securityHandler("jwt_auth",
  JWTAuthHandler.create(jwtAuthProvider));
----

When you generate the `link:../../apidocs/io/vertx/ext/web/Router.html[Router]` the router builder will solve the security schemes required for an operation.
It fails if there is a missing `AuthenticationHandler` required by a configured operation.

For debugging/testing purpose you can disable this check with `link:../../apidocs/io/vertx/ext/web/openapi/RouterBuilderOptions.html#setRequireSecurityHandlers-boolean-[setRequireSecurityHandlers]`

== Not Implemented Error

Router builder automatically mounts a default handler for operations without a specified handler.
This default handler fails the routing context with 405 `Method Not Allowed`/501 `Not Implemented` error.
You can enable/disable it with `link:../../apidocs/io/vertx/ext/web/openapi/RouterBuilderOptions.html#setMountNotImplementedHandler-boolean-[setMountNotImplementedHandler]`
and you can customize this error handling with `link:../../apidocs/io/vertx/ext/web/Router.html#errorHandler-int-io.vertx.core.Handler-[errorHandler]`

== Response Content Type Handler

Router builder automatically mounts a `link:../../apidocs/io/vertx/ext/web/handler/ResponseContentTypeHandler.html[ResponseContentTypeHandler]` handler when contract requires it.
You can disable this feature with `link:../../apidocs/io/vertx/ext/web/openapi/RouterBuilderOptions.html#setMountResponseContentTypeHandler-boolean-[setMountResponseContentTypeHandler]`

== Operation model

If you need to access to your operation model while handling the request,
you can configure the router builder to push it inside the `RoutingContext` with `link:../../apidocs/io/vertx/ext/web/openapi/RouterBuilderOptions.html#setOperationModelKey-java.lang.String-[setOperationModelKey]`:

[source,java]
----
options.setOperationModelKey("operationModel");
routerBuilder.setOptions(options);

// Add an handler that uses the operation model
routerBuilder
  .operation("listPets")
  .handler(
    routingContext -> {
      JsonObject operation = routingContext.get("operationModel");

      routingContext
        .response()
        .setStatusCode(200)
        .setStatusMessage("OK")
        // Write the response with operation id "listPets"
        .end(operation.getString("operationId"));
    });
----

== Body Handler

Router builder automatically mounts a `link:../../apidocs/io/vertx/ext/web/handler/BodyHandler.html[BodyHandler]` to manage request bodies.
You can configure the instance of `link:../../apidocs/io/vertx/ext/web/handler/BodyHandler.html[BodyHandler]` (e.g. to change upload directory) with `link:../../apidocs/io/vertx/ext/web/openapi/RouterBuilder.html#bodyHandler-io.vertx.ext.web.handler.BodyHandler-[bodyHandler]`.

== `multipart/form-data` validation

The validation handler separates file uploads and form attributes as explained:

* If the parameter doesn't have an encoding associated field:
 - If the parameter has `type: string` and `format: base64` or `format: binary` is a file upload with content-type `application/octet-stream`
 - Otherwise is a form attribute
* If the parameter has the encoding associated field is a file upload

The form attributes are parsed, converted in json and validated,
while for file uploads the validation handler just checks the existence and the content type.

== Custom global handlers

If you need to mount handlers that must be executed for each operation in your router before the operation specific handlers, you can use `link:../../apidocs/io/vertx/ext/web/openapi/RouterBuilder.html#rootHandler-io.vertx.core.Handler-[rootHandler]`

== Router builder handlers mount order

Handlers are loaded by the router builder in this order:

1. Body handler
2. Custom global handlers
4. Configured `link:../../apidocs/io/vertx/ext/web/handler/AuthenticationHandler.html[AuthenticationHandler]`s
5. Generated `link:../../apidocs/io/vertx/ext/web/validation/ValidationHandler.html[ValidationHandler]`
6. User handlers or "Not implemented" handler (if enabled)

== Generate the router

When you are ready, generate the router and use it:

[source,java]
----
Router router = routerBuilder.createRouter();

HttpServer server =
  vertx.createHttpServer(new HttpServerOptions().setPort(8080).setHost(
    "localhost"));
server.requestHandler(router).listen();
----

This method can fail with a `link:../../apidocs/io/vertx/ext/web/openapi/RouterBuilderException.html[RouterBuilderException]`.

[TIP]
====
If you need to mount all the router generated by router builder under the same parent path, you can use `link:../../apidocs/io/vertx/ext/web/Router.html#mountSubRouter-java.lang.String-io.vertx.ext.web.Router-[mountSubRouter]`:

[source,java]
----
Router global = Router.router(vertx);

Router generated = routerBuilder.createRouter();
global.mountSubRouter("/v1", generated);
----
====