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TypeScript extension for Yellicode

Generate TypeScript code using powerful TypeScript code generation templates! This Yellicode extension lets you generate TypeScript classes, interfaces, enumerations and their members from different kinds of models, using a fully typed code writer.

License: MIT

About Yellicode

Yellicode lets you build your own code generation templates with TypeScript. It consists of a Node.js CLI and extensible APIs, making it easy for developers to create, share and re-use code generators for their favorite programming languages and frameworks.

Check out our website for more.

Using the TypeScript package


In order to run a code generation template, you must have the CLI installed (@yellicode/cli) globally and have a valid codegenconfig.json file in your working directory. Please refer to the installation instructions and the quick start for more.


Open a terminal/command prompt in your working directory and install this package as a dev dependency:

npm install @yellicode/typescript --save-dev

Using the TypeScriptWriter

The main class for generating TypeScript code is the TypeScriptWriter. The TypeScriptWriter can work with 2 different model kinds as input:

Most TypeScriptWriter functions have 2 overloads which can be used for each different kind of input. For example, the writeClassBlock function has the following overloads:

  1. public writeClassBlock(cls: ClassDefinition, contents: (writer: TypeScriptWriter) => void): void
  2. public writeClassBlock(cls: elements.Type, contents: (writer: TypeScriptWriter) => void, options?: opts.ClassOptions): void

The first overload accepts a ClassDefinition, which has the following structure (comments left out for brevity):

export interface ClassDefinition extends TypeDefinition {   
    isAbstract?: boolean;    
    implements?: string[];    
    extends?: string[];    
    properties?: PropertyDefinition[];

When using this overload, you should build the definition in your code generation template. You can do this manually, but typically you would configure a JSON file as model (see the Yellicode quick start for a how-to) and transform that JSON structure to a TypeScript definition.

The second overload accepts a class instance from a Yellicode model and accepts an optional ClassOptions object to control code generation (internally, the Yellicode class is transformed to a ClassDefinition).


Note: a ZIP archive with working examples is also available for download here.

Example using a TypeScript code definition

This sample creates a simple TypeScript definition of a Task class, which is then provided to the TypeScriptWriter. You would typically create this definition from another structure (your own JSON model, using the 'model' parameter).

import { TextWriter } from '@yellicode/core';
import { Generator } from '@yellicode/templating';
import { TypeScriptWriter, ClassDefinition } from '@yellicode/typescript';

Generator.generate({ outputFile: './custom-sample.ts' }, (output: TextWriter) => {    
    const classDefinition: ClassDefinition = {
        name: 'Task',
        export: true,
        description: ['Represents an activity to be done.']
    }; = [
        { name: 'TaskDescription', typeName: 'string', accessModifier: 'public', description: ['Gets or sets a description of the task.'] },
        { name: 'IsFinished', typeName: 'boolean', accessModifier: 'public', description: ['Indicates if the task is finished.'] }

    const ts = new TypeScriptWriter(output);
    ts.writeClassBlock(classDefinition, () => { => {

The generated TypeScript code will look as follows:

* Represents an activity to be done.
export class Task {
	* Gets or sets a description of the task.
	public TaskDescription: string;

	* Indicates if the task is finished.
	public IsFinished: boolean;

Example using a Yellicode model

For navigating a Yellicode model in template code, you should also have the @yellicode/elements package installed in your working directory:

npm install @yellicode/elements --save-dev

This template generates a TypeScript code file with all classes in the model and, for each class, write property for each class attribute.

import { TextWriter } from '@yellicode/core';
import { Generator } from '@yellicode/templating';
import { TypeScriptWriter } from '@yellicode/typescript';
import * as elements from '@yellicode/elements';

Generator.generateFromModel({ outputFile: './model-based-sample.ts' }, (output: TextWriter, model: elements.Model) => {
    const ts = new TypeScriptWriter(output);

    model.getAllClasses().forEach(cls => {
        ts.writeClassBlock(cls, () => {
            cls.ownedAttributes.forEach(att => {
        }, { export: true });

API Documentation

For all TypeScriptWriter functions and options, check out the API documentation.