Load partially valid settings files.

This will load all the keys that are valid and log errors for the rest.

Author: rwb27

src/labthings_fastapi/thing.py

@@ -6,8 +6,10 @@
 """
 
 from __future__ import annotations
+import json
 from typing import TYPE_CHECKING, Any, Optional
 from pydantic import ValidationError
+from pydantic_core import InitErrorDetails
 from typing_extensions import Self
 from collections.abc import Mapping
 import logging
@@ -212,14 +214,48 @@ def load_settings(self) -> None:
 
         try:
             with open(setting_storage_path, "r", encoding="utf-8") as file_obj:
-                settings_model = self.settings.model.model_validate_json(
-                    file_obj.read()
+                settings = json.load(file_obj)
+                if not isinstance(settings, Mapping):
+                    raise TypeError("The settings file must be a JSON object.")
+            validation_errors: dict[str, ValidationError] = {}
+            for name, value in settings:
+                try:
+                    setting = self.settings[name]
+                    # Load the key from the JSON file using the setting's model
+                    model = setting.model.model_validate(value)
+                    setting.set_without_emit_from_model(model)
+                except ValidationError as e:
+                    validation_errors[name] = e
+                except KeyError:
+                    self.logger.warning(
+                        f"An extra key {name} was found in the settings file. "
+                        "It will be deleted the next time settings are saved."
+                    )
+            if validation_errors:
+                # If one or more settings didn't validate, combine them into a single
+                # Pydantic validation error.
+                error_details: list[InitErrorDetails] = []
+                for name, exc in validation_errors.items():
+                    for err in exc.errors():
+                        error_details.append(
+                            {
+                                "type": err["type"],
+                                "loc": (name,) + err["loc"],
+                                "input": err["input"],
+                                "ctx": err["ctx"] if "ctx" in err else {},
+                            }
+                        )
+                raise ValidationError.from_exception_data(
+                    "Some settings were not valid.",
+                    error_details,
                 )
-            for key, value in settings_model:
-                if value is None:
-                    continue  # `None` means the key was missing
-                self.settings[key].set_without_emit_from_model(value)
-        except (FileNotFoundError, JSONDecodeError, PermissionError, ValidationError):
+        except (
+            FileNotFoundError,
+            JSONDecodeError,
+            PermissionError,
+            ValidationError,
+            TypeError,
+        ):
             # Note that if the settings file is missing, we should already have returned
             # before attempting to load settings.
             self.logger.warning(