Building a server module

In this tutorial we’ll show you how to build a Group Office module. As an example we’re going to build a Music module.


Group Office is a JMAP-based server API and a webclient. We’ll start with implementing the JMAP server API.

Development environment

If you haven’t got your development environment set up, then please do this first.

You can install Group-Office like described in this manual and get started or use our Docker compose project that installs our images for development:

Required software

To follow this tutorial you need the following software installed:

  1. git. For version management.

  2. An editor to edit PHP and Javascript files.

  3. A HTTP client like Postman for testing the backend API without the User Interface.

Code standards

When writing code we following standards:

  1. Use tabs to indent code

  2. Use braces with all structures

  3. Don’t use ?> close tag at the end of class files

  4. One class per file

  5. YAGNI

Naming conventions







Database tables

lower_underscored (For windows compatibility) and singular eg. “contact” and not “contacts”

Database fields





We’re currently refactoring the whole code base. So you will encounter the namespaces “go” and “GO”. The “GO” namespace with capitals is old and you should not use it in new code. Legacy modules are found in “modules” folder and new modules are in “go/modules/<package>/<name>”.

Server module

The code for the module can be found at

The server modules are created in the following path:


The package is a group of modules that belong to each other. It is used to group modules per type or per customer.

So our music module will be created in:



Start with creating the database tables. The tables would be prefixed with the module name. For example “music_artist”.

Create the tables by importing this SQL into your database:

CREATE TABLE `music_album` (
  `id` int(11) NOT NULL,
  `artistId` int(11) NOT NULL,
  `name` varchar(190) COLLATE utf8mb4_unicode_ci NOT NULL,
  `releaseDate` date NOT NULL,
  `genreId` int(11) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

CREATE TABLE `music_artist` (
  `id` int(11) NOT NULL,
  `name` varchar(190) COLLATE utf8mb4_unicode_ci NOT NULL,
  `photo` binary(40) DEFAULT NULL,
  `createdAt` datetime NOT NULL,
  `modifiedAt` datetime NOT NULL,
  `createdBy` int(11) NOT NULL,
  `modifiedBy` int(11) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

CREATE TABLE `music_genre` (
  `id` int(11) NOT NULL,
  `name` varchar(190) COLLATE utf8mb4_unicode_ci NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

INSERT INTO `music_genre` (`id`, `name`) VALUES
(1, 'Pop'),
(2, 'Rock'),
(3, 'Blues'),
(4, 'Jazz');

ALTER TABLE `music_album`
  ADD KEY `artistId` (`artistId`),
  ADD KEY `genreId` (`genreId`);

ALTER TABLE `music_artist`
  ADD KEY `photo` (`photo`);

ALTER TABLE `music_genre`

ALTER TABLE `music_album`

ALTER TABLE `music_artist`

ALTER TABLE `music_genre`

ALTER TABLE `music_album`
  ADD CONSTRAINT `music_album_ibfk_1` FOREIGN KEY (`artistId`) REFERENCES `music_artist` (`id`) ON DELETE CASCADE,
  ADD CONSTRAINT `music_album_ibfk_2` FOREIGN KEY (`genreId`) REFERENCES `music_genre` (`id`);

ALTER TABLE `music_artist`
  ADD CONSTRAINT `music_artist_ibfk_1` FOREIGN KEY (`photo`) REFERENCES `core_blob` (`id`);

Database rules

  1. Also see naming conventions.

  2. Date’s use column type “DATE”.

  3. Date and time columns use type “DATETIME”.

  4. Foreign key’s must be defined for relationships. Think about cascading delete set to null or restrict. In general. Properties should always be cascaded and entities should be restricted. They should be cascaded by overriding the internalSave() function so all the application logic will be executed like cleaning up links, logging etc.

  5. We often choose a varchar to be 190 characters so it can be indexed on all database versions.

  6. Columns modifiedBy (int), createdBy (int), createdAt (DATETIME), modifiedAt (DATETIME) are automatically set by Group Office.

Code generator

We’ve written a command line tool to make it easy to start with a new module. When you’ve created your database tables then you can run it to generate the models and controllers. You need to install the “Development tools” module that is part of the “Community” package. Login as administrator and go to System Settings -> Modules.

Then you can run it at any time from within the project directory to add new model properties, models or controllers:

php {PATH_TO_GROUPOFFICE}/cli.php community/dev/Module/init --package=tutorial --name=music


When using docker-compose use: command with:

docker-compose exec groupoffice-master php /usr/local/share/groupoffice/cli.php community/dev/Module/init --package=tutorial --name=music

the command should output:

Generating model/Album.php
Updating go\modules\community\music\model\Album with new properties
Generating model/Artist.php
Updating go\modules\community\music\model\Artist with new properties
Generating model/Genre.php
Updating go\modules\community\music\model\Genre with new properties

This will generate:

  1. Module.php, required for every module. Contains Author info and controls the installation.

  2. views/extjs3, The webclient code. We’ll get to that later.

  3. language/en.php, translation file.

  4. install/install.sql, uninstall.sql and updates.php, these files handle installation and upgrading.

  5. model, this folder contains all models.


Docker runs as root and will write these files as root.

So you need to change the ownership to your own user by running:

sudo chown -R $USER:$USER src/master/www/go/modules/tutorial

Property and Entity models

You can read more about entities and properties here. By default, the tool generates only “Property” models. It doesn’t know which models should be “Entities”. An entity can be modified by the API directly and a property is only modifiable through an entity. For example an email address of a contact is a property of the entity contact.

So the first step is to change some properties into JMAP entities. In this example Artist and Genre are entities.

So in model/Artist.php change:

use go\core\orm\Property;

class Artist extends Property {


use go\core\jmap\Entity;

class Artist extends Entity {

Do the same for Genre.

Now run the code generator tool again and it will generate controllers for these entities. It should output:

Generating controller/Artist.php
Generating controller/Genre.php


Now we must define relations in the models. Add the “albums” relation to the artist by creating a new public property:

 * The albums created by the artist
 * @var array
 public $albums;

And then change the mapping:

protected static function defineMapping() {
    return parent::defineMapping()
            ->addTable("music_artist", "artist")
            ->addArray('albums', Album::class, ['id' => 'artistId']);


When making changes to the database, model properties or mappings, you must run http://localhost/install/upgrade.php in your browser to rebuild the cache.

Custom properties

For the sake of learning, we will add a property to our model, that does not directly stem from its own table. In this example, we want to display the number of albums for a certain artist in the artist grid.

The first step is to declare the property in the model and to implement a getter:

/** @var int */
protected $albumCount;

// (...)

public function getAlbumCount() :int
  return $this->albumCount;

The next step is to update the defineMapping method, to actually count the albums:

protected static function defineMapping() {
              return parent::defineMapping()
                                              ->addTable("music_artist", "artist")
                                              ->addMap('albums', Album::class, ['id' => 'artistId']);
                                              ->addQuery((new Query())->select('COUNT( AS albumCount')
                                                      ->join('music_album', 'alb','')->groupBy(['alb.artistId']) );

The albumCount property is simply retrieved by counting the albums that are related to the current artist.


Please note that in this example, we do not define a setter method. It should not be possible to manually set an album counter, since it is a counter of related properties.

There is actually a better way of getting an album count. In order to keep things simple, one can remove the extra query and redefine the getAlbumCount() function as follows:

public function getAlbumCount() :int
  return count($this->albums);


To define a nice name for the module create language/en.php:

return [
                'name' => 'Music',
                'description' => 'Simple module for the Group-Office tutorial'

If you’re interested you can read more about translating here.

Install the module

Now we’ve got our basic server API in place. Now it’s time to install the module at:

System Settings -> Modules. There should be a Tutorial package with the “music” module.

Check the box to install it.


If it doesn’t show up it might be due to cache. Run /install/upgrade.php to clear it.

Connecting to the API with POSTMan

Using the API with Postman is not strictly necessary but it’s nice to get a feel on how the backend API works.

Install Postman or another tool to make API requests. Download it from here:


Send a POST request to:


use content type:


And the following request body:

   "username": "admin",
   "password": "adminadmin"

When successfully logged on you should get a response with status:

201 Authentication is complete, access token created

Find the “accessToken” property and save it. From now on you can do API requests to:


You must set the access token as a header on each request:

Auhorization: Bearer 5b7576e5c50ac30f0e53373f0fa614cedbdbe49df7637
Content-Type: application/json

Create an artist

To create an artist, POST this JSON body:

  ["Artist/set", {
    "create": {
    "clientId-1": {
      "name": "The Doors",
      "albums": [
        {"name": "The Doors", "artistId": 1, "releaseDate": "1967-01-04", "genreId" :2},
        {"name": "Strange Days", "artistId": 1, "releaseDate": "1967-09-25", "genreId" :2}


  }, "call1"],

  ["community/dev/Debugger/get", {}, "call4"]

Query artists

The Artist/query method is used to retrieve an ordered / filtered list of id’s for displaying a list of artists. We’ll do a direct followup call to “Artist/get” to retrieve the full artist data as well. We can Use the special “#” parameter to use a previous query result as parameter. Read more on this at the JMAP website.

POST the following to make the request:

["Artist/query", {}, "call1"],
  "#ids": {
    "resultOf": "call1",
    "path": "/ids"
["community/dev/Debugger/get", {}, "call3"]

Query filters

When doing “Artist/query” requests, it’s possible to filter the results. You can pass for example:

{"filter": {"text" : "Foo"}}

We generally use the “text” filter for a quick search query. We also want to filter artists by their album genres. We can implement this in our “Artist” entity in by overriding the “filter” method:

 * This function returns the columns to search when using the "text" filter.
public static function textFilterColumns() {
  return ['name'];

       * Defines JMAP filters
       * Adds the 'genres' filter which can be an array of genre id's.
       * @link
       * @return Filters
      protected static function defineFilters() {
              return parent::defineFilters()
                      ->add('genres', function (\go\core\db\Criteria $criteria, $value, \go\core\orm\Query $query, array $filter) {
                              if (!empty($value)) {
                                      $query->join('music_album', 'album', 'album.artistId =')
                                      ->groupBy(['']) // group the results by id to filter out duplicates because of the join
                                      ->where(['album.genreId' => $value]);

After defining this you can filter on genre by posting:

["Artist/query", {"filter":{"genres":[1,2,3]}}, "call1"],

JMAP API protocol

These are some basic request examples. Read more on about the protocol.

Module installation

When you’re done with the module, you should export your finished database into:


Put all ‘DROP TABLE x’ commands in:


Module upgrades

When the database changes later on you can put upgrade queries and php functions in:


For example:

$updates["201808161606"][] = "ALTER TABLE ...";
$updates["201808161606"][] = function() {
  //some migration code here

The timestamp is important. Use YYYYMMDDHHII. All the module upgrades will be mixed together and put into chronological order so dependant modules won’t break.

Custom Fields

Custom development is a fact of life, even for your simple tutorial module. In this example, we will add a few custom fields to different entities.

First, we need to update the database. For an entity to be customized, we need to add a table that follows the convention below:


We will have to write a database migration. Open go/modules/tutorial/music/updates.php and add the following code:

$updates['202002041445'][] = <<<'EOT'
CREATE TABLE IF NOT EXISTS `music_artist_custom_fields`
    CONSTRAINT `music_artist_custom_fields_ibfk_1` FOREIGN KEY(id) REFERENCES music_artist (id)

The next step is to add the CustomFieldsTrait trait to the Artist model.

namespace go\modules\tutorial\music\model;

use go\core\jmap\Entity;
use go\core\orm\CustomFieldsTrait;

 * Artist model
 * @copyright (c) 2020, Intermesh BV
 * @author Merijn Schering <>
 * @license AGPLv3
class Artist extends Entity {
    use CustomFieldsTrait;

    // Et cetera...

After rerunning the install script, the Custom fields screen in System settings should look somewhat like this:


For now, we are done. In the next chapter, we will see how custom fields are made available in the web client.

ACL Entities

In certain cases, you want to either have some private entities or entities that are shared with certain groups of other users. This section deals with developing entities that have some form of access control.

In our tutorial module, we will add a ACL entity named ‘review’, which will allow you to add reviews to albums and control with whom you want to share your guilty pleasures.

The first step is to create the music_review table. Open install/updates.php and add the code below:

$updates['202002071045'][] = <<<'EOT'
    ( `id` INT(11) NOT NULL PRIMARY KEY,
    `albumId` INT(11) NOT NULL,
    `aclId` INT(11) NOT NULL,
    `createdBy` int(11) NOT NULL,
    `modifiedBy` int(11) NOT NULL,
    `title` VARCHAR(190) COLLATE utf8mb4_unicode_ci NOT NULL,
    `body` TEXT collate utf8mb4_unicode_ci NOT NULL

     ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
$updates['202002071045'][] = <<<'EOT'
ALTER TABLE `music_review`
    ADD KEY `aclId` (`aclId`),
    ADD KEY `albumId` (`albumId`);
$updates['202002071045'][] = <<<'EOT'
ALTER TABLE `music_review`
    ADD CONSTRAINT `music_review_fk1` FOREIGN KEY (`albumId`) REFERENCES `music_album` (`id`) ON DELETE CASCADE,
    ADD CONSTRAINT `music_review_fk2` FOREIGN KEY (`aclId`) REFERENCES `core_acl` (`id`);

Run the database install script again and you should see the newly created table in the database.

The next step is to create a model, which we extend from the AclOwnerEntity class:


namespace go\modules\tutorial\music\model;

use Exception;
use go\core\acl\model\AclOwnerEntity;
use go\core\orm\Query;

class Review extends AclOwnerEntity
    /** @var int */
    public $id;
    /** @var int */
    public $aclId;
    /** @var int */
    public $createdBy;
    /** @var int */
    public $albumId;
    /** @var int */
    public $modifiedBy;
    /** @var int */
    public $rating;
    /** @var string */
    public $title;
    /** @var string */
    public $body;
    /** @var string */
    public $albumtitle;

    protected static function defineMapping()
        return parent::defineMapping()
            ->addQuery((new Query())->select(' AS albumtitle')
                ->join('music_album', 'a', ''));

    protected function internalSave()
        if($this->isNew()) {
            $this->albumtitle = go()->getDbConnection()
                ->where(['id' => $this->albumId])


        return parent::internalSave();

    protected static function internalDelete(Query $query)
        //Create clone to avoid changes to the  original delete query object
        $deleteQuery = clone $query;

        //Select albums of artists affected by this delete


        return parent::internalDelete($query);

     * Our review has effect on Artist entities because they implement getAlbumCount().
     * @param array $albumIds
     * @throws Exception
    private static function changeArtist(array $albumIds) {
                ->select(', null, 0')
                ->from('music_artist', 'art')
                ->join('music_album', 'alb', 'alb.artistId =')
                ->where('', 'IN', $albumIds)

    protected static function defineFilters()
        return parent::defineFilters()
            ->add('albumId', function (\go\core\db\Criteria $criteria, $value, \go\core\orm\Query $query, array $filter) {
                if (!empty($value)) {
                    $query->where(['music_review.albumId' => $value]);



Interestingly, we need to make sure that the Artist entity is updated upon adding or deleting a review. We force this by overriding the internalSave and internalDelete methods.

The end

Now you’re done with the server code of the module. It is time to move on and build the web client!