Plugin Guide

Frictionless is built on top of a powerful plugins system which is used internally and allows to extend the framework.

Plugin Interface#

Here is a list of available hooks that you can implement in your plugin:

create_check
create_control
create_dialect
create_loader
create_parser
create_server
create_step
create_storage
create_type

To create a plugin you need:

create a module called frictionless_<name> available in PYTHONPATH
subclass the Plugin class and override one of the methods above

Please consult with "API Reference" for in-detail information about the Plugin interface and how these methods can be implemented.

Plugin Example#

Let's say we're interested in supporting the csv2k format that we have just invented. For simplicity, let's use a format that is exactly the same with CSV.

First of all, we need to create a frictionless_csv2k module containing a Plugin implementation and a Parser implementation but we're going to re-use the CsvParser as our new format is the same:

frictionless_csv2k.py

Python

from frictionless import Plugin, system
from frictionless.plugins.csv import CsvParser

class Csv2kPlugin(Plugin):
    def create_parser(self, file):
        if file.format == "csv2k":
            return Csv2kParser(file)

class Csv2kParser(CsvParser):
    pass

system.register('csv2k', Csv2kPlugin())

Now, we can use our new format in any of the Frictionless functions that accept a table source, for example, extract or Table:

Python

from frictionless import extract

rows = extract('data/table.csv2k')
print(rows)

This example is over-simplified to show the high-level mechanics but writing Frictionless Plugins is designed to be easy. For inspiration, you can check the frictionless/plugins directory and learn from real-life examples. Also, in the Frictionless codebase there are many Check, Control, Dialect, Loader, Parser, and Server implementations - you can read their code for better understanding of how to write your own subclass or reach out to us for support.