Frictionless is built on top of a powerful plugins system which is used internally and allows to extend the framework.
To create a plugin you need:
frictionless_<name>available in PYTHONPATH
Please consult with System/Plugin for in-detail information about the Plugin interface and how these methods can be implemented.
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:
from frictionless import Plugin, system from frictionless.plugins.csv import CsvParser class Csv2kPlugin(Plugin): def create_parser(self, resource): if resource.format == "csv2k": return Csv2kParser(resource) 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,
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
Server implementations - you can read their code for better understanding of how to write your own subclass or reach out to us for support.
Plugin representation It's an interface for writing Frictionless plugins. You can implement one or more methods to hook into Frictionless system.
(source: Any, *, control: Optional[Control] = None) -> Optional[Adapter]
(resource: Resource) -> Optional[Loader]
(resource: Resource) -> Optional[Parser]
Detect field candidates
(candidates: List[dict]) -> Optional[List[dict]]
Hook into resource detection
(resource: Resource) -> None