Decorator Metdata: expose array element type

TSC 175, target ES6, Node 5.6

Sample class with decorated properties:

@sg.DMClass
export class User implements IUser {
    @sg.DMProperty
    firstName: string;
    @sg.DMProperty
    lastName: string;
    @sg.DMProperty
    friends: User[];
}

Property decorator:

export function DMProperty(target: any, key: string) {
    var type = Reflect.getMetadata("design:type", target, key);
}

Current behaviour: When the decorator gets called for property “friends”, “type” is “Array” and the captured type (“User”) is lost.

Expected behaviour “type” should contain the captured type (“User”), too

Following very dirty work-around does the job: I modified tsc’s method “emitSerializedTypeNode”:

function emitSerializedTypeNode(node) {
    if (node) {
        console.log("*** emitSerializedTypeNode: node.kind: ", node.kind);
        switch (node.kind) {
            ...
            case 157:
                // Begin dirty ---------------------------------------------------------------------------
                var _elemType = node.elementType.typeName.text;
                write("{name: 'Array<" + _elemType + ">', type:'Array', elemType:'" + _elemType + "'}");
                console.log("*** emitSerializedTypeNode: Array, type: ", node.elementType.typeName.text);
                // End dirty -----------------------------------------------------------------------------
                return;
            case 150:
            ...

Best Mind

[IonelLupu]

You may see low reaction numbers for this feature but it is waited by a lot of people. We need to transform JavaScript/Typescript and make it compete with languages like Java.

For example, this feature will allow me to build a very beautiful database ORM just by using class properties and no any workarounds with decorators.

[listepo-alterpost]

Hi, any news?