Improve config final validation (#1917)

esphome/final_validate.py

@@ -0,0 +1,57 @@
+from abc import ABC, abstractmethod, abstractproperty
+from typing import Dict, Any
+import contextvars
+
+from esphome.types import ConfigFragmentType, ID, ConfigPathType
+import esphome.config_validation as cv
+
+
+class FinalValidateConfig(ABC):
+    @abstractproperty
+    def data(self) -> Dict[str, Any]:
+        """A dictionary that can be used by post validation functions to store
+        global data during the validation phase. Each component should store its
+        data under a unique key
+        """
+
+    @abstractmethod
+    def get_path_for_id(self, id: ID) -> ConfigPathType:
+        """Get the config path a given ID has been declared in.
+
+        This is the location under the _validated_ config (for example, with cv.ensure_list applied)
+        Raises KeyError if the id was not declared in the configuration.
+        """
+
+    @abstractmethod
+    def get_config_for_path(self, path: ConfigPathType) -> ConfigFragmentType:
+        """Get the config fragment for the given global path.
+
+        Raises KeyError if a key in the path does not exist.
+        """
+
+
+FinalValidateConfig.register(dict)
+
+# Context variable tracking the full config for some final validation functions.
+full_config: contextvars.ContextVar[FinalValidateConfig] = contextvars.ContextVar(
+    "full_config"
+)
+
+
+def id_declaration_match_schema(schema):
+    """A final-validation schema function that applies a schema to the outer config fragment of an
+    ID declaration.
+
+    This validator must be applied to ID values.
+    """
+    if not isinstance(schema, cv.Schema):
+        schema = cv.Schema(schema, extra=cv.ALLOW_EXTRA)
+
+    def validator(value):
+        fconf = full_config.get()
+        path = fconf.get_path_for_id(value)[:-1]
+        declaration_config = fconf.get_config_for_path(path)
+        with cv.prepend_path([cv.ROOT_CONFIG_PATH] + path):
+            return schema(declaration_config)
+
+    return validator