Merge pull request #174 from 0Hughman0/custom-validation-error

created MetaValidationError

cassini/meta.py

@@ -15,7 +15,14 @@
 )
 from typing_extensions import Tuple, cast, Self, Type
 
-from pydantic import BaseModel, ConfigDict, Field, create_model, JsonValue
+from pydantic import (
+    BaseModel,
+    ConfigDict,
+    Field,
+    create_model,
+    JsonValue,
+    ValidationError,
+)
 from pydantic.fields import FieldInfo
 
 
@@ -33,6 +40,15 @@ class MetaCache(BaseModel):
     )
 
 
+class MetaValidationError(ValueError):
+    def __init__(self, *, validation_error: ValidationError, file: Path):
+        message = f"Invalid data in file: {file}, due to the following validation error:\n\n{validation_error}"
+
+        super().__init__(message)
+        self.file = file
+        self.validation_error = validation_error
+
+
 class Meta:
     """
     Like a dictionary, except linked to a json file on disk. Caches the value of the json in itself.
@@ -80,10 +96,15 @@ def fetch(self) -> MetaCache:
         overwritten, it'll just be loaded.
         """
         if self.file.exists():
-            self._cache = self.model.model_validate_json(
-                self.file.read_text(), strict=False
-            )
+            try:
+                self._cache = self.model.model_validate_json(
+                    self.file.read_text(), strict=False
+                )
+            except ValidationError as e:
+                raise MetaValidationError(validation_error=e, file=self.file)
+
             self._cache_born = time.time()
+
         return self._cache
 
     def refresh(self) -> None:
@@ -100,7 +121,6 @@ def write(self) -> None:
         jsons = self._cache.model_dump_json(
             exclude_defaults=True, exclude={"__pydantic_extra__"}
         )
-        # Danger moment - writing bad cache to file.
         with self.file.open("w", encoding="utf-8") as f:
             f.write(jsons)
 
@@ -126,15 +146,25 @@ def __setattr__(self, name: str, value: Any) -> None:
             super().__setattr__(name, value)
         else:
             self.fetch()
-            setattr(self._cache, name, value)
+
+            try:
+                setattr(self._cache, name, value)
+            except ValidationError as e:
+                raise MetaValidationError(validation_error=e, file=self.file)
+
             self.write()
 
     def __delitem__(self, key: str) -> None:
         self.fetch()
         excluded = self._cache.model_dump(
             exclude={"__pydantic_extra__", key}, exclude_defaults=True
         )
-        self._cache = self.model.model_validate(excluded)
+        # it might not be possible for this to happen, because all fields have to have defaults.
+        try:
+            self._cache = self.model.model_validate(excluded)
+        except ValidationError as e:
+            raise MetaValidationError(validation_error=e, file=self.file)
+
         self.write()
 
     def __repr__(self) -> str:

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "cassini"
-version = "0.3.0a9"
+version = "0.3.0a10"
 description = "A tool to structure experimental work, data and analysis using Jupyter Lab."
 authors = ["0Hughman0 <rammers2@hotmail.co.uk>"]
 license = "GPL-3.0-only"

tests/test_meta.py

@@ -4,7 +4,7 @@
 
 import pytest # type: ignore[import]
 from cassini import HomeTierBase, NotebookTierBase
-from cassini.meta import MetaAttr, MetaManager, Meta, MetaCache
+from cassini.meta import MetaAttr, MetaManager, Meta, MetaCache, MetaValidationError
 from cassini.testing_utils import get_Project, patch_project, patched_default_project
 
 import pydantic
@@ -132,11 +132,11 @@ def test_jsonable(mk_meta):
     meta = mk_meta
 
     # attributes have to be serialisable in some way!
-    with pytest.raises(pydantic.ValidationError):
+    with pytest.raises(MetaValidationError):
         meta['object'] = object
 
     # values must be json values. If you want type coersion, define a meta attr!
-    with pytest.raises(pydantic.ValidationError):
+    with pytest.raises(MetaValidationError):
         meta['pathlike'] = pathlib.Path().absolute()
 
     # type changes are allowed without meta definition.
@@ -158,7 +158,7 @@ class Model(MetaCache):
 
     assert meta['strict_str'] == 'default'
 
-    with pytest.raises(pydantic.ValidationError):
+    with pytest.raises(MetaValidationError):
         meta['strict_str'] = 5
 
     meta['strict_str'] = 'new val'
@@ -205,7 +205,7 @@ def test_started_requires_timezone(patched_default_project):
 
     WP1, = create_tiers(['WP1'])
 
-    with pytest.raises(pydantic.ValidationError):
+    with pytest.raises(MetaValidationError):
         WP1.started = datetime.datetime.now()
 
 
@@ -269,7 +269,7 @@ class Fourth(NotebookTierBase):
 
     assert obj.description == 'new description'
 
-    with pytest.raises(pydantic.ValidationError):
+    with pytest.raises(MetaValidationError):
         obj.description = 124
 
     obj = project['Second1Third1']
@@ -286,6 +286,65 @@ class Fourth(NotebookTierBase):
     assert 'started' in obj.meta.model.model_fields
 
 
+def test_meta_validation_error_has_path(tmp_path):
+    class Model(MetaCache):
+        strict_str: str = 'default'
+
+    meta = Meta(tmp_path / 'test.json', Model)
+
+    with pytest.raises(MetaValidationError, match=str('test.json')):
+        meta.strict_str = 10
+
+
+def test_bad_setattr_raises_meta_error(tmp_path):
+    class Model(MetaCache):
+        strict_str: str = 'default'
+
+    meta = Meta(tmp_path / 'test.json', Model)
+
+    with pytest.raises(MetaValidationError, match=str('test.json')):
+        meta.strict_str = 10
+
+
+def test_bad_setitem_raises_meta_error(tmp_path):
+    class Model(MetaCache):
+        strict_str: str = 'default'
+
+    meta = Meta(tmp_path / 'test.json', Model)
+
+    with pytest.raises(MetaValidationError, match=str('test.json')):
+        meta['strict_str'] = 10
+
+
+def test_bad_fetch_raises_meta_error(tmp_path):
+    class Model(MetaCache):
+        strict_str: str = 'default'
+
+    file = tmp_path / 'test.json'
+
+    file.write_text('{"strict_str": 10}')
+
+    meta = Meta(tmp_path / 'test.json', Model)
+
+    with pytest.raises(MetaValidationError, match=str('test.json')):
+        meta.fetch()
+
+
+def test_bad_del_raises_meta_error(tmp_path):
+    class Model(MetaCache):
+        strict_str: str
+
+    file = tmp_path / 'test.json'
+
+    file.write_text('{"strict_str": "value"}')
+
+    meta = Meta(tmp_path / 'test.json')
+    meta.model = Model  # currently, we cannot set model=Model, because all fields must have defaults. 
+
+    with pytest.raises(MetaValidationError, match=str('test.json')):
+        del meta["strict_str"]
+
+
 def test_cas_field_meta():
     m = MetaAttr(None, str, str, cas_field='core')
     assert m.cas_field == 'core'