Backend App Development

This document details instructions and guidelines for developing backend apps to be used with the SODAR Core framework.

It is recommended to read Project App Development before this document.

Backend App Basics

Backend apps are intended to be used by other apps via their plugin without requiring hard-coded imports. They may provide their own views for e.g. Ajax API functionality, but mostly they’re intended to be internal “helper” apps as the name suggests.

Prerequisites

See Project App Development.

Models

No specific model implementation is required. However, it is strongly to refer to objects using sodar_uuid fields instead of the database private key.

BackendAppPlugin

The plugin is detected and retrieved using a BackendAppPlugin.

Declaring the Plugin

Create a file plugins.py in your app’s directory. In the file, declare a BackendAppPlugin class implementing projectroles.plugins.BackendPluginPoint. Within the class, implement member variables and functions as instructed in comments and docstrings.

from projectroles.plugins import BackendPluginPoint
from .urls import urlpatterns

class BackendAppPlugin(BackendPluginPoint):
    """Plugin for registering a backend app"""
    name = 'example_backend_app'
    title = 'Example Backend App'
    urls = urlpatterns
    # ...

The following variables and functions are mandatory:

name: Plugin name. If only introducing a single plugin in your app, this should match the app name. For multiple plugins within a single app, additional plugins should start with the app name, e.g. yourapp_xxx. This ensures the correct highlighting of active apps in the UI. Note that the name variables of plugins are expected to be unique, although not currently strictly enforced.
title: Plugin title to be displayed in the UI. In the case of a backend plugin, this will be mostly visible in the Siteinfo App views.
icon: Iconify collection and icon name (e.g. mdi:home).
description: Verbose description of the app.
get_api(): Method for retrieving the API class for the backend. The user should implement this API class to be retrieved.

Implementing the following is optional:

javascript_url: Path to on demand includeable Javascript file.
css_url: Path to on demand includeable CSS file.
info_settings: List of names for app-specific Django settings to be displayed for administrators in the siteinfo app.
get_statistics(): Return statistics for the siteinfo app. See details in the siteinfo documentation.
get_object_link(): Return object link for a Timeline event.
get_extra_data_link(): Return extra data link for a Timeline event.

Hint

If you want to define multiple plugins within a single app, see the Multi-Plugin Apps documentation.

Using the Plugin

To retrieve the API for the plugin, use the function projectroles.plugins.get_backend_api() as follows:

from projectroles.plugins import get_backend_api
example_api = get_backend_api('example_backend_app')

if example_api:     # Make sure the API is there, and only after that..
    pass            # ..do stuff with the API

Including Backend Javascript/CSS

If you want Javascript or CSS files to be associated with your plugin you can set the javascript_url or css_url variables to specify the path to your file. Note that these should correspond to STATIC paths under your app directory.

class BackendPlugin(BackendPluginPoint):

    name = 'example_backend_app'
    title = 'Example Backend App'
    javascript_url = 'example_backend_app/js/example.js'
    css_url = 'example_backend_app/css/example.css'

The get_backend_include template-tag will return a <script> or <link> html tag with your specific file path, to be used in a template of your app making use of the backend plugin:

{% load projectroles_common_tags %}
{% get_backend_include 'example_backend_app' 'js' as javascript_include_tag %}
{{ javascript_include_tag|safe }}

{% get_backend_include 'example_backend_app' 'css' as css_include_tag %}
{{ css_include_tag|safe }}

This will result in the following HTML:

<script type="text/javascript" src="/static/example.js"></script>
<link rel="stylesheet" type="text/css" href="/static/example.css"/>

Be sure to use the backend plugin’s name (not the title) as the key and filter the result by safe, so the tag won’t be auto-escaped.