Guide to developing MOLGENIS Frontend

Tools and compiling

When developing client code, you will need to following tools:

  • Node v8.9.0 (LTS version) and included NPM version
  • Yarn v0.24.5 or greater

All client code and the corresponding package.json file should be located in a <molgenis-module>/src/main/frontend directory.

Node and Yarn are installed inside the frontend/node and frontend/node/yarn/dist directories, and are used by the maven build to deploy install and compile your client code. Your compiled client code is then placed inside the target/classes directory of your maven module.


To start developing a MOLGENIS plugin, we encourage you to use the molgenis-vue-template.

If you do not have the vue-cli, use

npm install -g vue-cli

If you have the vue-cli installed you can use the following steps to quickly install a working Vue template

cd <molgenis-module>/src/main
vue init molgenis/molgenis-vue-template frontend

then answer the questions to setup your frontend working directory:

  1. Name: The name of the project. The metadata-manager was created with the name 'metadata-manager', as you might expect.
  2. Description: A description of your project
  3. author: Email adres or name of the author
  4. Vuex: This is used for state management
  5. vue-router: This is used for routing
  6. Flow: This is used for typing
  7. MOLGENIS: And answering yes on the MOLGENIS plugin question will ensure that your compiled client code is placed inside the target/classes directory

Inside the newly created frontend directory, the following three commands can be used to install, develop and test client code:

yarn install
yarn run dev
yarn run tests

Third party libraries can be added:

yarn add <library_name>

or removed:

yarn remove <library_name>

using yarn.

Yarn produces a yarn.lock file. Commit this file to your Git repository as it ensures future builds to use the versions that were used to create the client code.

When running your client code in development on port 3000, it will help to run the MOLGENIS locally on port 8080. The molgenis-vue-template comes with a proxy table that will redirect any REST calls to localhost:8080

Some guidelines

Below you can find some guidelines + code examples for stuff that we view is standard when creating a MOLGENIS plugin.

Use Bootstrap for your CSS1

<div class="container">
    <div class="row">
        <div class="col">
            <h1>Bootstrap grid system is amazing!</h1>

Use Font awesome for icons1

<i class="fa fa-plus"></i>

Write unit tests for mutations, actions, getters and other pure JS code

// utils.spec.js

import { swapArrayElements } from 'utils'

describe('swapArrayElements', () => {
    it('should swap the location of two objects in an array', () => {
        const array = [1, 2, 3, 4, 5]

        const actual = swapArrayElements(array, 2, 3)
        const expected = [1, 2, 4, 3, 5]


Create named Vue components

// ComponentA.vue

    export default {
        name: 'component-A'

To allow theme changes to affect all specific color sets, use sass mixins and variables1 when setting colors

<style lang="scss">
  @import "~variables";
  @import "~mixins";

   .some_class {
      background-color: $red;

    .some_other_class {
      background-color: darken($red, 20%)

When using Vuex for your state, use Flow to add typing your state parameters1

// state.js

// @flow
export type State = {
  message: ?string
  isUpdated: boolean

const state: State = {
  message: null,
  isUpdated: false

Use i18n for labels

<button>{{ 'back-to-home-button' | i18n }}</button>

Use the INITIAL_STATE object to load configuration from the server inside Freemarker templates

// index.html

window.__INITIAL_STATE__ = {
    baseUrl: '/',
    lng: 'en',
    fallbackLng: 'en'

When writing actions or mutations for your store, use constants for the different types

// mutations.js

export const SET_MESSAGE = '__SET_MESSAGE__'

export default {
    [SET_MESSAGE] (state, message) {
        state.message = message

More to come...

1 Configuration is provided in the molgenis-vue-template


To run yarn commands on a windows machine, you will have to open up a shell terminal as administrator

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