Skip to content

Injection

Injection

Coyaml injects configuration values into functions using @coyaml and Annotated[..., YResource].

Explicit path

from typing import Annotated
from coyaml import YResource, coyaml

@coyaml
def handler(user: Annotated[str, YResource('debug.db.user')]) -> str:
    return user

By name with optional mask

When YResource has no path, Coyaml searches by parameter name. Use mask to constrain search to dotted paths.

from typing import Annotated
from coyaml import YResource, coyaml

@coyaml(mask='debug.**')
def connect(user: Annotated[str | None, YResource()] = None) -> str | None:
    return user

Notes: - Optional or default None → injects None when not found - Multiple matches + unique=True (default) → error with candidate paths; restrict the mask or set unique=False - If the value is a YNode and the annotation expects a Pydantic model, it is converted via .to(Model)

Relative path in YResource

You can provide a relative dotted path in YResource(path) and combine it with a decorator mask.

Relative means "suffix match" over full dotted paths, filtered by mask first. The first match is injected; if multiple matches exist and unique=True, an error is raised with candidates.

from typing import Annotated
from coyaml import YResource, coyaml

@coyaml(mask='env.**')
def handler(svcs: Annotated[dict[str, int] | None, YResource('services')] = None) -> dict[str, int] | None:
    return svcs

To force an absolute path, prefix with ^:

@coyaml
def handler_abs(svcs: Annotated[dict[str, int], YResource('^env.services')]) -> dict[str, int]:
    return svcs