Adds wrapper code for ClassList routines in Project

RAT/classlist.py

@@ -63,12 +63,28 @@ def __repr__(self):
 
     def __setitem__(self, index: int, set_dict: dict[str, Any]) -> None:
         """Assign the values of an existing object's attributes using a dictionary."""
+        self._setitem(index, set_dict)
+
+    def _setitem(self, index: int, set_dict: dict[str, Any]) -> None:
+        """Auxiliary routine of "__setitem__" used to enable wrapping."""
         self._validate_name_field(set_dict)
         for key, value in set_dict.items():
             setattr(self.data[index], key, value)
 
+    def __delitem__(self, index: int) -> None:
+        """Delete an object from the list by index."""
+        self._delitem(index)
+
+    def _delitem(self, index: int) -> None:
+        """Auxiliary routine of "__delitem__" used to enable wrapping."""
+        del self.data[index]
+
     def __iadd__(self, other: Sequence[object]) -> 'ClassList':
         """Define in-place addition using the "+=" operator."""
+        return self._iadd(other)
+
+    def _iadd(self, other: Sequence[object]) -> 'ClassList':
+        """Auxiliary routine of "__iadd__" used to enable wrapping."""
         if not hasattr(self, '_class_handle'):
             self._class_handle = type(other[0])
         self._check_classes(self + other)

RAT/project.py

@@ -1,11 +1,14 @@
 """The project module. Defines and stores all the input data required for reflectivity calculations in RAT."""
 
+import copy
+import functools
 import numpy as np
-from pydantic import BaseModel, FieldValidationInfo, field_validator, model_validator
-from typing import Any
+from pydantic import BaseModel, FieldValidationInfo, field_validator, model_validator, ValidationError
+from typing import Any, Callable
 
 from RAT.classlist import ClassList
 import RAT.models
+from RAT.utils.custom_errors import formatted_pydantic_error
 
 try:
     from enum import StrEnum
@@ -46,6 +49,27 @@ class Geometries(StrEnum):
                       'contrasts': 'Contrast'
                       }
 
+values_defined_in = {'backgrounds.value_1': 'background_parameters',
+                     'backgrounds.value_2': 'background_parameters',
+                     'backgrounds.value_3': 'background_parameters',
+                     'backgrounds.value_4': 'background_parameters',
+                     'backgrounds.value_5': 'background_parameters',
+                     'resolutions.value_1': 'resolution_parameters',
+                     'resolutions.value_2': 'resolution_parameters',
+                     'resolutions.value_3': 'resolution_parameters',
+                     'resolutions.value_4': 'resolution_parameters',
+                     'resolutions.value_5': 'resolution_parameters',
+                     'layers.thickness': 'parameters',
+                     'layers.SLD': 'parameters',
+                     'layers.roughness': 'parameters',
+                     'contrasts.data': 'data',
+                     'contrasts.background': 'backgrounds',
+                     'contrasts.nba': 'bulk_in',
+                     'contrasts.nbs': 'bulk_out',
+                     'contrasts.scalefactor': 'scalefactors',
+                     'contrasts.resolution': 'resolutions',
+                     }
+
 
 class Project(BaseModel, validate_assignment=True, extra='forbid', arbitrary_types_allowed=True):
     """Defines the input data for a reflectivity calculation in RAT.
@@ -109,7 +133,9 @@ def check_class(cls, value: ClassList, info: FieldValidationInfo) -> ClassList:
         return value
 
     def model_post_init(self, __context: Any) -> None:
-        """Initialises the class in the ClassLists for empty data fields, and sets protected parameters."""
+        """Initialises the class in the ClassLists for empty data fields, sets protected parameters, and wraps
+        ClassList routines to control revalidation.
+        """
         for field_name, model in model_in_classlist.items():
             field = getattr(self, field_name)
             if not hasattr(field, "_class_handle"):
@@ -119,6 +145,17 @@ def model_post_init(self, __context: Any) -> None:
                                                                 fit=True, prior_type=RAT.models.Priors.Uniform, mu=0,
                                                                 sigma=np.inf))
 
+        # Wrap ClassList routines - when any of these routines are called, the wrapper will force revalidation of the
+        # model, handle errors and reset previous values if necessary.
+        class_lists = ['parameters', 'bulk_in', 'bulk_out', 'qz_shifts', 'scalefactors', 'background_parameters',
+                       'backgrounds', 'resolution_parameters', 'resolutions', 'custom_files', 'data', 'layers',
+                       'contrasts']
+        methods_to_wrap = ['_setitem', '_delitem', '_iadd', 'append', 'insert', 'pop', 'remove', 'clear', 'extend']
+        for class_list in class_lists:
+            attribute = getattr(self, class_list)
+            for methodName in methods_to_wrap:
+                setattr(attribute, methodName, self._classlist_wrapper(attribute, getattr(attribute, methodName)))
+
     @model_validator(mode='after')
     def cross_check_model_values(self) -> 'Project':
         """Certain model fields should contain values defined elsewhere in the project."""
@@ -170,5 +207,43 @@ def check_allowed_values(self, attribute: str, field_list: list[str], allowed_va
             for field in field_list:
                 value = getattr(model, field)
                 if value and value not in allowed_values:
-                    setattr(model, field, '')
-                    raise ValueError(f'The parameter "{value}" has not been defined in the list of allowed values.')
+                    raise ValueError(f'The value "{value}" in the "{field}" field of "{attribute}" must be defined in '
+                                     f'"{values_defined_in[attribute + "." + field]}".')
+
+    def _classlist_wrapper(self, class_list: 'ClassList', func: Callable):
+        """Defines the function used to wrap around ClassList routines to force revalidation.
+
+        Parameters
+        ----------
+        class_list : ClassList
+            The ClassList defined in the "Project" model that is being modified.
+        func : Callable
+            The routine being wrapped.
+
+        Returns
+        -------
+        wrapped_func : Callable
+            The wrapped routine.
+        """
+        @functools.wraps(func)
+        def wrapped_func(*args, **kwargs):
+            """Run the given function and then revalidate the "Project" model. If any exception is raised, restore
+            the previous state of the given ClassList and report details of the exception.
+            """
+            previous_state = copy.deepcopy(getattr(class_list, 'data'))
+            return_value = None
+            try:
+                return_value = func(*args, **kwargs)
+                Project.model_validate(self)
+            except ValidationError as e:
+                setattr(class_list, 'data', previous_state)
+                error_string = formatted_pydantic_error(e)
+                # Use ANSI escape sequences to print error text in red
+                print('\033[31m' + error_string + '\033[0m')
+            except (TypeError, ValueError):
+                setattr(class_list, 'data', previous_state)
+                raise
+            finally:
+                del previous_state
+            return return_value
+        return wrapped_func

RAT/utils/custom_errors.py

@@ -0,0 +1,26 @@
+"""Defines routines for custom error handling in RAT."""
+
+from pydantic import ValidationError
+
+
+def formatted_pydantic_error(error: ValidationError) -> str:
+    """Write a custom string format for pydantic validation errors.
+
+    Parameters
+    ----------
+    error : pydantic.ValidationError
+        A ValidationError produced by a pydantic model
+
+    Returns
+    -------
+    error_str : str
+        A string giving details of the ValidationError in a custom format.
+    """
+    num_errors = error.error_count()
+    error_str = f'{num_errors} validation error{"s"[:num_errors!=1]} for {error.title}'
+    for this_error in error.errors():
+        error_str += '\n'
+        if this_error['loc']:
+            error_str += ' '.join(this_error['loc']) + '\n'
+        error_str += '  ' + this_error['msg']
+    return error_str

tests/test_classlist.py

@@ -142,6 +142,20 @@ def test_setitem_same_name_field(two_name_class_list: 'ClassList', new_values: d
         two_name_class_list[0] = new_values
 
 
+def test_delitem(two_name_class_list: 'ClassList', one_name_class_list: 'ClassList') -> None:
+    """We should be able to delete elements from a ClassList with the del operator."""
+    class_list = two_name_class_list
+    del class_list[1]
+    assert class_list == one_name_class_list
+
+
+def test_delitem_not_present(two_name_class_list: 'ClassList') -> None:
+    """If we use the del operator to delete an index out of range, we should raise an IndexError."""
+    class_list = two_name_class_list
+    with pytest.raises(IndexError, match=re.escape("list assignment index out of range")):
+        del class_list[2]
+
+
 @pytest.mark.parametrize("added_list", [
     (ClassList(InputAttributes(name='Eve'))),
     ([InputAttributes(name='Eve')]),

tests/test_custom_errors.py

@@ -0,0 +1,20 @@
+"""Test the utils.custom_errors module."""
+
+from pydantic import create_model, ValidationError
+import pytest
+
+import RAT.utils.custom_errors
+
+
+def test_formatted_pydantic_error() -> None:
+    """When a pytest ValidationError is raised we should be able to take it and construct a formatted string."""
+
+    # Create a custom pydantic model for the test
+    TestModel = create_model('TestModel', int_field=(int, 1), str_field=(str, 'a'))
+
+    with pytest.raises(ValidationError) as exc_info:
+        TestModel(int_field='string', str_field=5)
+
+    error_str = RAT.utils.custom_errors.formatted_pydantic_error(exc_info.value)
+    assert error_str == ('2 validation errors for TestModel\nint_field\n  Input should be a valid integer, unable to '
+                         'parse string as an integer\nstr_field\n  Input should be a valid string')