34 | Update error messages

Author: LeanderCS

.github/workflows/test-lib-building.yaml

@@ -25,7 +25,7 @@ jobs:
         id: build
 
       - name: Install built library
-        run: pip install dist/*.whl
+        run: pip install "$(ls dist/*.whl | head -n 1)[optional]"
 
       - name: Verify library usage - Part I
         run: |

docs/changelog.rst

@@ -4,6 +4,20 @@ Changelog
 All notable changes to this project will be documented in this file.
 
 
+[0.2.0] - 2025-04-07
+--------------------
+
+Added
+^^^^^
+- getErrorMessages
+
+Changed
+^^^^^^^
+- Updated error handling: The first error for each field is now returned in a combined format,
+  enabling more detailed and flexible error handling on the frontend. :doc:`Check it out <guides/frontend_validation>`
+- Errors received through external_api request get logged.
+
+
 [0.1.2] - 2025-03-29
 --------------------
 

docs/conf.py

@@ -1,7 +1,7 @@
 project = "flask-inputfilter"
 copyright = "2025, Leander Cain Slotosch"
 author = "Leander Cain Slotosch"
-release = "0.1.2"
+release = "0.2.0"
 
 extensions = ["sphinx_rtd_theme"]
 

docs/guides/frontend_validation.rst

@@ -0,0 +1,66 @@
+Frontend Validation
+===================
+
+Keeping frontend and backend validations synchronized can take a lot of time and
+may lead to unexpected behavior if not maintained properly.
+
+With ``flask_inputfilter`` you can easily implement an extra route to keep up with the validation and
+use the same ``InputFilter`` definition both for the frontend and backend validation.
+
+
+Example implementation
+~~~~~~~~~~~~~~~~~~~~~~~
+
+.. code-block:: python
+
+    from flask import Response, Flask
+    from flask_inputfilter import InputFilter
+    from flask_inputfilter.Condition import ExactlyOneOfCondition
+    from flask_inputfilter.Enum import RegexEnum
+    from flask_inputfilter.Filter import StringTrimFilter, ToIntegerFilter, ToNullFilter
+    from flask_inputfilter.Validator import IsIntegerValidator, IsStringValidator, RegexValidator
+
+    app = Flask(__name__)
+
+    class UpdateZipcodeInputFilter(InputFilter):
+        def __init__(self):
+            super().__init__()
+
+            self.add(
+                'id',
+                required=True,
+                filters=[ToIntegerFilter(), ToNullFilter()],
+                validators=[
+                    IsIntegerValidator()
+                ]
+            )
+
+            self.add(
+                'zipcode',
+                filters=[StringTrimFilter()],
+                validators=[
+                    RegexValidator(
+                        pattern=RegexEnum.POSTAL_CODE.value,
+                        error_message='The zipcode is not in the correct format.'
+                    )
+                ]
+            )
+
+    @app.route('/form-update-zipcode', methods=['POST'])
+    @UpdateZipcodeInputFilter.validate()
+    def updateZipcode():
+        return Response(status=200)
+
+This basic implementation allows you to validate the form in the frontend through the route ``/form-update-zipcode``.
+If the validation is successful, it returns an empty response with the status code 200.
+If it fails, it returns an response with the status code 400 and the corresponding errors in json format.
+
+If the validation for the zipcode fails, the response would be:
+
+.. code-block:: python
+
+    {
+        "zipcode": "The zipcode is not in the correct format."
+    }
+
+Validation errors of conditions can be found in the ``_condition`` field.

docs/guides/index.rst

@@ -6,3 +6,4 @@ Guides
     :glob:
 
     create_own_components
+    frontend_validation

flask_inputfilter/InputFilter.py

@@ -1,3 +1,4 @@
+import json
 import re
 from typing import Any, Callable, Dict, List, Optional, Tuple, Union
 
@@ -26,7 +27,7 @@ class InputFilter:
         "__global_validators",
         "__data",
         "__validated_data",
-        "__error_message",
+        "__errors",
     )
 
     def __init__(self, methods: Optional[List[str]] = None) -> None:
@@ -37,7 +38,7 @@ def __init__(self, methods: Optional[List[str]] = None) -> None:
         self.__global_validators: List[BaseValidator] = []
         self.__data: Dict[str, Any] = {}
         self.__validated_data: Dict[str, Any] = {}
-        self.__error_message: str = ""
+        self.__errors: Dict[str, str] = {}
 
     @final
     def add(
@@ -269,10 +270,10 @@ def clear(self) -> None:
         self.__global_validators.clear()
         self.__data.clear()
         self.__validated_data.clear()
-        self.__error_message = ""
+        self.__errors.clear()
 
     @final
-    def getErrorMessage(self) -> str:
+    def getErrorMessage(self, field_name: str) -> str:
         """
         Retrieves and returns a predefined error message.
 
@@ -286,7 +287,23 @@ def getErrorMessage(self) -> str:
         Returns:
             str: A string representing the predefined error message.
         """
-        return self.__error_message
+        return self.__errors.get(field_name)
+
+    @final
+    def getErrorMessages(self) -> Dict[str, str]:
+        """
+        Retrieves all error messages associated with the fields in the
+        input filter.
+
+        This method aggregates and returns a dictionary of error messages
+        where the keys represent field names, and the values are their
+        respective error messages.
+
+        Returns:
+            Dict[str, str]: A dictionary containing field names as keys and
+                            their corresponding error messages as values.
+        """
+        return self.__errors
 
     @final
     def getValue(self, name: str) -> Any:
@@ -516,8 +533,8 @@ def isValid(self) -> bool:
         try:
             self.validateData(self.__data)
 
-        except (ValidationError, Exception) as e:
-            self.__error_message = str(e)
+        except ValidationError as e:
+            self.__errors = e.args[0]
             return False
 
         return True
@@ -549,6 +566,7 @@ def validateData(
         """
         validated_data = self.__validated_data
         data = data or self.__data
+        errors = {}
 
         for field_name, field_info in self.__fields.items():
             value = data.get(field_name)
@@ -562,30 +580,38 @@ def validateData(
             external_api = field_info.external_api
             copy = field_info.copy
 
-            if copy:
-                value = validated_data.get(copy)
-
-            if external_api:
-                value = self.__callExternalApi(
-                    external_api, fallback, validated_data
-                )
+            try:
+                if copy:
+                    value = validated_data.get(copy)
 
-            value = self.__applyFilters(filters, value)
+                if external_api:
+                    value = self.__callExternalApi(
+                        external_api, fallback, validated_data
+                    )
 
-            value = self.__validateField(validators, fallback, value) or value
+                value = self.__applyFilters(filters, value)
+                value = (
+                    self.__validateField(validators, fallback, value) or value
+                )
+                value = self.__applySteps(steps, fallback, value) or value
+                value = self.__checkForRequired(
+                    field_name, required, default, fallback, value
+                )
 
-            value = self.__applySteps(steps, fallback, value) or value
+                validated_data[field_name] = value
 
-            value = self.__checkForRequired(
-                field_name, required, default, fallback, value
-            )
+            except ValidationError as e:
+                errors[field_name] = str(e)
 
-            validated_data[field_name] = value
+        try:
+            self.__checkConditions(validated_data)
+        except ValidationError as e:
+            errors["_condition"] = str(e)
 
-        self.__checkConditions(validated_data)
+        if errors:
+            raise ValidationError(errors)
 
         self.__validated_data = validated_data
-
         return validated_data
 
     @classmethod
@@ -626,7 +652,11 @@ def wrapper(
                     g.validated_data = input_filter.validateData()
 
                 except ValidationError as e:
-                    return Response(status=400, response=str(e))
+                    return Response(
+                        status=400,
+                        response=json.dumps(e.args[0]),
+                        mimetype="application/json",
+                    )
 
                 return f(*args, **kwargs)
 
@@ -724,8 +754,14 @@ def __callExternalApi(
                 Raised if the external API call does not succeed and no
                 fallback value is provided.
         """
+        import logging
+
         import requests
 
+        logger = logging.getLogger(__name__)
+
+        data_key = config.data_key
+
         requestData = {
             "headers": {},
             "params": {},
@@ -753,25 +789,22 @@ def __callExternalApi(
             response = requests.request(**requestData)
 
             if response.status_code != 200:
-                raise ValidationError(
-                    f"External API call failed with "
-                    f"status code {response.status_code}"
+                logger.error(
+                    f"External_api request inside of InputFilter "
+                    f"failed: {response.text}"
                 )
+                raise
 
             result = response.json()
 
-            data_key = config.data_key
             if data_key:
                 return result.get(data_key)
 
             return result
-        except Exception as e:
+        except Exception:
             if fallback is None:
-                self.__error_message = str(e)
-
                 raise ValidationError(
-                    f"External API call failed for field "
-                    f"'{config.data_key}'."
+                    f"External API call failed for field " f"'{data_key}'."
                 )
 
             return fallback
@@ -829,7 +862,9 @@ def __checkForRequired(
 
         raise ValidationError(f"Field '{field_name}' is required.")
 
-    def __checkConditions(self, validated_data: dict) -> None:
+    def __checkConditions(self, validated_data: Dict[str, Any]) -> None:
         for condition in self.__conditions:
             if not condition.check(validated_data):
-                raise ValidationError(f"Condition '{condition}' not met.")
+                raise ValidationError(
+                    f"Condition '{condition.__class__.__name__}' not met."
+                )

setup.py

@@ -2,11 +2,11 @@
 
 setup(
     name="flask_inputfilter",
-    version="0.1.2",
+    version="0.2.0",
     license="MIT",
     author="Leander Cain Slotosch",
     author_email="[email protected]",
-    description="A library to filter and validate input data in "
+    description="A library to easily filter and validate input data in "
     "Flask applications",
     long_description=open("README.rst").read(),
     long_description_content_type="text/x-rst",
@@ -16,10 +16,14 @@
     ),
     install_requires=[
         "flask>=2.1",
-        "pillow>=8.0.0",
-        "requests>=2.22.0",
         "typing_extensions>=3.6.2",
     ],
+    extras_require={
+        "optional": [
+            "pillow>=8.0.0",
+            "requests>=2.22.0",
+        ],
+    },
     classifiers=[
         "Operating System :: OS Independent",
         "Programming Language :: Python :: 3.14",