JSON schema

In MIDL, we use classes to describe the JSON schema for request content or response content. Client-side SDKs and server-side stubs will convert class instances from/to JSON.

Request content JSON schema

A MIDL method that has a @:requestContentType describes an endpoint that requires a request content body. For these method, the last parameter will be send to server as request content body, and the type of the last parameter references to a JSON schema for the request content body.

interface IMyService {
  @:route("PUT", "users/{userId}")
  function setProfile(userId:String, contentBody:RequestType):Future<Void>;

In the above code block, RequestType must be a type that describes JSON schema for request content body.

Response content JSON schema

The return type of a MIDL method must be jsonStream.rpc.Future<ResponseType>, where ResponseType is the data structure of JSON for HTTP response.

interface IMyService {
  @:route("PUT", "users/{userId}")
  function getProfile(userId:String):Future<ResponseType>;

In the above code block, RequestType must be a type that describes JSON schema for response content body.

Built-in types for JSON schema

Primary types

MIDL reuses some standard types in Haxe language as primary types of JSON schema.

  • Int and Float correspond to JavaScript Number literal, e.g. 1.2, -3.4, 3.2349E-13
  • String corresponds to JavaScript String literal, e.g. "string value".
  • Bool corresponds to JavaScript Boolean literal, which could be false or true.

Array types

In MIDL, haxe.ds.Vector corresponds to JavaScript Array literal, and the type parameter of Vector is the element type.

For example, Vector<Int> accepts JSON like [2, 4, 5], and Vector<Bool> accepts JSON like [false, true, true].

Custom class types

In MIDL, a class defines the schema of a JSON object literal.

For example,

// This file is at src/haxe/userSdk/model/Models.hx
package userSdk.model;

@:final class UserProfile {
  public function new() {}
  public var name:String;
  public var email:String;
  public var age:Int;

This class accepts JSON like { "name": "Zhang San", "email": "zs@host.com", age: 18 }.

Note that you must not omit the constructor public function new() {}, otherwise client-side SDKs and server-side stubs will not be able to convert a UserProfile from/to JSON.