--- title: How to plugin --- ## How to write a plugin A short introductory guide for plugin beginners. ### Should it be a plugin? First of all figure out what your plugin / code should do. If you want to change how InvenTree base mechanics and business logic work, a plugin will not be sufficient. Maybe fork the project or better [start a discussion](https://github.com/inventree/InvenTree/discussions) on GitHub. There might be an easier / established way to do what you want. If you want to remove parts of the user interface -> remove the permissions for those objects / actions and the users will not see them. If you add a lot of code (over ~1000 LOC) maybe split it into multiple plugins to make upgrading and testing simpler. ### It will be a plugin! Great. Now please read the [plugin documentation](./plugins.md) to get an overview of the architecture. It is rather short as a the (builtin) mixins come with extensive docstrings. ### Pick your building blocks Consider the usecase for your plugin and define the exact function of the plugin, maybe wrtie it down in a short readme. Then pick the mixins you need (they help reduce custom code and keep the system reliable if internal calls change). - Is it just a simple REST-endpoint that runs a function ([ActionMixin](./plugins/action.md)) or a parser for a custom barcode format ([BarcodeMixin](./plugins/barcode.md))? - How does the user interact with the plugin? Is it a UI separate from the main InvenTree UI ([UrlsMixin](./plugins/urls.md)), does it need multiple pages with navigation-links ([NavigationMixin](./plugins/navigation.md)). - Will it make calls to external APIs ([APICallMixin](./plugins/api.md) helps there)? - Do you need to run in the background ([ScheduleMixin](./plugins/schedule.md)) or when things in InvenTree change ([EventMixin](./plugins/event.md))? - Does the plugin need configuration that should be user changeable ([SettingsMixin](./plugins/settings.md)) or static (just use a yaml in the config dir)? - You want to receive webhooks? Do not code your own untested function, use the WebhookEndpoint model as a base and override the perform_action method. - Do you need the full power of Django with custom models and all the complexity that comes with that – welcome to the danger zone and [AppMixin](./plugins/app.md). The plugin will be treated as a app by django and can maybe rack the whole instance. ### Define the metadata Do not forget to [declare the metadata](./plugins.md#plugin-options) for your plugin, those will be used in the settings. At least provide a weblink so users can file issues / reach you. ### Development guidelines If you want to make your life easier, try to follow these guidelines; break where it makes sense for your use case. - keep it simple - more that 1000 LOC are normally to much for a plugin - use mixins where possible - we try to keep coverage high for them so they are not likely to break - do not use internal functions - if a functions name starts with `_` it is internal and might change at any time - keep you imports clean - the APIs for plugins and mixins are young and evolving. Use ``` from plugin import IntegrationPluginBase, registry from plugin.mixins import APICallMixin, SettingsMixin, ScheduleMixin, BarcodeMixin ``` - deliver as a package - pip is great for dependency management and pypi can serve as a transparent and reliable delivery infrastructure - if you need to use a private infrastructure, use the 'Releases' functions in GitHub or Gitlab. Point to the 'latest' release endpoint when installing to make sure the update function works - tag your GitHub repo with 'inventree' and 'inventreeplugins' to make discovery easier - use GitHub actions to test your plugin regularly (you can [schedule actions](https://docs.github.com/en/actions/learn-github-actions/events-that-trigger-workflows#schedule)) against the 'latest' [docker-build](https://hub.docker.com/r/inventree/inventree) of InvenTree - if you use the AppMixin pin your plugin against the stable branch of InvenTree, your migrations might get messed up otherwise ### A simple example This example adds a new action under `/api/action/sample` using the ActionMixin. ``` py title="sampleactionplugin.py" # -*- coding: utf-8 -*- # (1) """sample implementation for ActionPlugin""" # (2) from plugin import IntegrationPluginBase from plugin.mixins import ActionMixin class SampleActionPlugin(ActionMixin, IntegrationPluginBase): """ Use docstrings for everything... pls # (2) """ PLUGIN_NAME = "SampleActionPlugin" ACTION_NAME = "sample" # metadata AUTHOR = "Sample Author" DESCRIPTION = "A very basic plugin with one mixin" PUBLISH_DATE = "22.02.2222" VERSION = "1.2.3" # We recommend semver and increase the major version with each new major release of InvenTree WEBSITE = "https://example.com/" LICENSE = "MIT" # use what you want - OSI approved is ♥ # Everything form here is for the ActionMixin def perform_action(self): print("Action plugin in action!") def get_info(self): return { "user": self.user.username, "hello": "world", } def get_result(self): return True # This is returned to the client ``` 1. It is recommended to put each plugin into it's own file, this is not required 2. Please document you functions and classes - following PEP8 or black is recommended