🛠️ Domain Modifiers

Fetchez includes a Modifier Engine in its ModifierRegistry that can automatically mutate your YAML recipes as they are loaded, allowing for complete runtime control of the pipeline.

Using a Modifier

Add a modifiers argument to the top of your YAML recipe:

---
project:
  name: "My_Project"

modifiers:
  - name: exclude_module
    args:
      modules: margrav/charts
region: [-120.0, -119.75, 33.0, 33.25]
modules:
  - bundle: my-bathymetry-bundle

What happens under the hood?

By specifying the modifier: exclude_module, the engine intercepts your recipe and removes the named margrav and charts modules from the module Bundle my-bathymetry-bundle. Modifiers take an input recipe config and do something to or with it and return the possibly mutated bundle, right before sending to the core Fetchez engine for processing.

Extending Modifiers (Plugins and Extensions)

Fetchez is generic. If you are building a custom tool (like a specialized DEM engine), you can register your own recipe modifiers in Python. Make a directory called ‘my_project/recipes/modifiers’ and put all your modifier python files within it:

from fetchez.recipes.modifiers import BaseModifier

class WeatherModifier(BaseModifier):
    name = "wrf_weather"

    @classmethod
    def apply(cls, config):
        config["region"] = [-180, 180, -90, 90] # Force global fetch
        return config

Then register your project with fetchez in your pyproject.toml:

[project.entry-points."fetchez.recipes.modifiers"]
my_project_modifiers = "my_project.recipes.modifiers"