Add more declaratives to prevent possible errors and make construction more direct

AGENTS.md

@@ -22,7 +22,8 @@ poetry add flask-inputfilter
 Create validation schemas by inheriting from `InputFilter`:
 
 ```python
-from flask_inputfilter import InputFilter, field
+from flask_inputfilter import InputFilter
+from flask_inputfilter.declarative import field, global_filter
 from flask_inputfilter.filters import ToIntegerFilter, StringTrimFilter
 from flask_inputfilter.validators import IsIntegerValidator, LengthValidator
 
@@ -41,8 +42,7 @@ class UserInputFilter(InputFilter):
     )
 
     # Global filters/validators apply to all fields
-    _global_filters = [StringTrimFilter()]
-    _global_validators = []
+    global_filter(StringTrimFilter())
 ```
 
 ### 2. Usage in Flask Routes

README.md

@@ -68,7 +68,7 @@ A more detailed guide can be found [in the docs](https://leandercs.github.io/fla
 
 ```python
 from flask_inputfilter import InputFilter
-from flask_inputfilter.declarative import field
+from flask_inputfilter.declarative import condition, field
 from flask_inputfilter.conditions import ExactlyOneOfCondition
 from flask_inputfilter.enums import RegexEnum
 from flask_inputfilter.filters import StringTrimFilter, ToIntegerFilter, ToNullFilter
@@ -101,9 +101,9 @@ class UpdateZipcodeInputFilter(InputFilter):
         ]
     )
 
-    _conditions = [
+    condition(
         ExactlyOneOfCondition(['zipcode', 'city'])
-    ]
+    )
 ```
 
 

docs/source/changelog.rst

@@ -4,6 +4,53 @@ Changelog
 All notable changes to this project will be documented in this file.
 
 
+[0.7.2] - 2025-09-28
+--------------------
+
+Changed
+^^^^^^^
+- Changed the way how to use the new decorator ``_condition``, ``_global_filter``, ``_global_validator`` and ``_model``.
+  They should no longer be assigned to a variable, but should be set with the corresponding declarative method.
+
+  ``_condition = [Example()]`` => ``condition(Example())``
+
+  ``_global_filter = [Example()]`` => ``global_filter(Example())``
+
+  ``_global_validator = [Example()]`` => ``global_validator(Example())``
+
+  ``_model = Example`` => ``model(Example)``
+
+  The previous way is still supported, but is not recommended because it is not streightforward and could lead to confusion.
+  The new methods also support multiple calls and also mass assignment.
+
+  Both of the following examples are valid and have the same effect:
+
+  .. code-block:: python
+
+        class ExampleInputFilter(InputFilter):
+            field1: str = field()
+            field2: str = field()
+            condition(ExactlyOneOfCondition(['field1', 'field2']))
+
+            field3: str = field()
+            field4: str = field()
+            condition(AtLeastOneOfCondition(['field3', 'field4']))
+
+
+  .. code-block:: python
+
+        class ExampleInputFilter(InputFilter):
+            field1: str = field()
+            field2: str = field()
+            field3: str = field()
+            field4: str = field()
+
+            condition(
+                ExactlyOneOfCondition(['field1', 'field2']),
+                AtLeastOneOfCondition(['field3', 'field4'])
+            )
+
+
 [0.7.1] - 2025-09-27
 --------------------
 
@@ -24,13 +71,13 @@ Added
 
   ``self.add`` => ``field``
 
-  ``self.add_condition`` => ``_conditions``
+  ``self.add_condition`` => ``condition``
 
-  ``self.add_global_filter`` => ``_global_filters``
+  ``self.add_global_filter`` => ``global_filter``
 
-  ``self.add_global_validator`` => ``_global_validators``
+  ``self.add_global_validator`` => ``global_validator``
 
-  ``self.add_model`` => ``_model``
+  ``self.add_model`` => ``model``
 
   **Before**:
     .. code-block:: python
@@ -65,13 +112,13 @@ Added
                 validators=[IsIntegerValidator()]
             )
 
-            _conditions = [ExactlyOneOfCondition(['zipcode', 'city'])]
+            condition(ExactlyOneOfCondition(['zipcode', 'city']))
 
-            _global_filters = [StringTrimFilter()]
+            global_filter(StringTrimFilter())
 
-            _global_validators = [IsStringValidator()]
+            global_validator(IsStringValidator())
 
-            _model = UserModel
+            model(UserModel)
 
   The Change is fully backward compatible, but the new way is more readable
   and maintainable.

docs/source/index.rst

@@ -77,7 +77,7 @@ Definition
             validators=[IsStringValidator()]
         )
 
-        _conditions = [ExactlyOneOfCondition(['zipcode', 'city'])]
+        condition(ExactlyOneOfCondition(['zipcode', 'city']))
 
 Usage
 ^^^^^

docs/source/options/condition.rst

@@ -6,7 +6,7 @@ Condition
 Overview
 --------
 
-Conditions are added using the ``_conditions`` class attribute. They evaluate the combined input data, ensuring that inter-field dependencies and relationships (such as equality, ordering, or presence) meet predefined rules.
+Conditions are added using the ``condition()`` declarative. They evaluate the combined input data, ensuring that inter-field dependencies and relationships (such as equality, ordering, or presence) meet predefined rules.
 
 Example
 -------
@@ -24,7 +24,7 @@ Example
             validators=[IsStringValidator()]
         )
 
-        _conditions = [OneOfCondition(['id', 'name'])]
+        condition(OneOfCondition(['id', 'name']))
 
 Available Conditions
 --------------------

docs/source/options/declarative_api.rst

@@ -0,0 +1,227 @@
+Declarative API
+===============
+
+Overview
+--------
+
+The Declarative API is the modern, recommended way to define InputFilters in flask-inputfilter.
+It uses Python decorators and class-level declarations to create clean, readable, and maintainable
+input validation definitions.
+
+Key Features
+------------
+
+- **Clean Syntax**: Define fields, conditions, and global components directly in class definition
+- **Type Safety**: Integrates well with type hints and IDEs
+- **Inheritance Support**: Full support for class inheritance and MRO
+- **Model Integration**: Automatic serialization to dataclasses, Pydantic models, and more
+- **Multiple Element Support**: Register multiple components at once for concise definitions
+
+Core Components
+---------------
+
+The Declarative API consists of four main decorators:
+
++----------------------+--------------------------------------------+
+| Decorator            | Purpose                                    |
++======================+============================================+
+| ``field()``          | Define individual input fields             |
++----------------------+--------------------------------------------+
+| ``condition()``      | Add cross-field validation conditions     |
++----------------------+--------------------------------------------+
+| ``global_filter()``  | Add filters applied to all fields         |
++----------------------+--------------------------------------------+
+| ``global_validator()``| Add validators applied to all fields      |
++----------------------+--------------------------------------------+
+| ``model()``          | Associate with a model class              |
++----------------------+--------------------------------------------+
+
+Quick Example
+-------------
+
+.. code-block:: python
+
+    from flask_inputfilter import InputFilter
+    from flask_inputfilter.declarative import field, condition, global_filter, global_validator, model
+    from flask_inputfilter.filters import StringTrimFilter, ToLowerFilter
+    from flask_inputfilter.validators import IsStringValidator, LengthValidator, EmailValidator
+    from flask_inputfilter.conditions import EqualCondition
+    from dataclasses import dataclass
+
+    @dataclass
+    class User:
+        username: str
+        email: str
+        password: str
+
+    class UserRegistrationFilter(InputFilter):
+        # Field definitions with individual configuration
+        username = field(
+            required=True,
+            validators=[LengthValidator(min_length=3, max_length=20)]
+        )
+
+        email = field(
+            required=True,
+            validators=[EmailValidator()]
+        )
+
+        password = field(required=True, validators=[LengthValidator(min_length=8)])
+        password_confirmation = field(required=True)
+
+        # Global components - applied to all fields
+        global_filter(StringTrimFilter(), ToLowerFilter())
+        global_validator(IsStringValidator())
+
+        # Cross-field validation
+        condition(EqualCondition('password', 'password_confirmation'))
+
+        # Model association
+        model(User)
+
+ Declarative API
+----------------
+
+.. code-block:: python
+
+    class MyFilter(InputFilter):
+        name = field(required=True, validators=[IsStringValidator()])
+        email = field(required=True, validators=[EmailValidator()])
+
+        global_filter(StringTrimFilter())
+        condition(RequiredCondition('name'))
+
+Inheritance and MRO
+-------------------
+
+The Declarative API fully supports Python's inheritance and Method Resolution Order (MRO):
+
+.. code-block:: python
+
+    class BaseUserFilter(InputFilter):
+        # Base fields
+        name = field(required=True, validators=[IsStringValidator()])
+
+        # Base global components
+        global_filter(StringTrimFilter())
+
+    class ExtendedUserFilter(BaseUserFilter):
+        # Additional fields
+        email = field(required=True, validators=[EmailValidator()])
+        age = field(required=False, validators=[IsIntegerValidator()])
+
+        # Additional global components (inherited ones are preserved)
+        global_validator(LengthValidator(min_length=1))
+
+        # Conditions
+        condition(RequiredCondition('email'))
+
+Field Override
+~~~~~~~~~~~~~~
+
+You can override fields from parent classes:
+
+.. code-block:: python
+
+    class BaseFilter(InputFilter):
+        name = field(required=False)  # Optional in base
+
+    class StrictFilter(BaseFilter):
+        name = field(required=True, validators=[LengthValidator(min_length=2)])  # Override
+
+Multiple Element Registration
+-----------------------------
+
+You can register multiple components at once for cleaner definitions:
+
+.. code-block:: python
+
+    class CompactFilter(InputFilter):
+        name = field(required=True)
+        email = field(required=True)
+
+        # Multiple global filters
+        global_filter(StringTrimFilter(), ToLowerFilter(), RemoveExtraSpacesFilter())
+
+        # Multiple global validators
+        global_validator(IsStringValidator(), NotEmptyValidator())
+
+        # Multiple conditions
+        condition(
+            RequiredCondition('name'),
+            RequiredCondition('email'),
+            EqualCondition('password', 'password_confirmation')
+        )
+
+Model Integration
+-----------------
+
+The Declarative API seamlessly integrates with various model types:
+
+Dataclasses
+~~~~~~~~~~~
+
+.. code-block:: python
+
+    from dataclasses import dataclass
+
+    @dataclass
+    class User:
+        name: str
+        email: str
+
+    class UserFilter(InputFilter):
+        name = field(required=True, validators=[IsStringValidator()])
+        email = field(required=True, validators=[EmailValidator()])
+
+        model(User)
+
+    # Usage
+    filter_instance = UserFilter()
+    user = filter_instance.validate_data({'name': 'John', 'email': '[email protected]'})
+    # user is a User dataclass instance
+
+Pydantic Models
+~~~~~~~~~~~~~~~
+
+.. code-block:: python
+
+    from pydantic import BaseModel
+
+    class User(BaseModel):
+        name: str
+        email: str
+
+    class UserFilter(InputFilter):
+        name = field(required=True, validators=[IsStringValidator()])
+        email = field(required=True, validators=[EmailValidator()])
+
+        model(User)
+
+TypedDict
+~~~~~~~~~
+
+.. code-block:: python
+
+    from typing import TypedDict
+
+    class UserDict(TypedDict):
+        name: str
+        email: str
+
+    class UserFilter(InputFilter):
+        name = field(required=True, validators=[IsStringValidator()])
+        email = field(required=True, validators=[EmailValidator()])
+
+        model(UserDict)
+
+Next Steps
+----------
+
+For detailed information about each component, see:
+
+- :doc:`Field Decorator <field_decorator>` - Complete field configuration options
+- :doc:`Global Decorators <global_decorators>` - Global filters, validators, and conditions
+- :doc:`Conditions <condition>` - Cross-field validation conditions
+- :doc:`Filters <filter>` - Available filters and custom filter creation
+- :doc:`Validators <validator>` - Available validators and custom validator creation