feat: allow passing a validator function to perform complex or customized validations on parameters

Author: Garcel

README.md

@@ -65,6 +65,7 @@ All parameters can have default values, and automatic validation.
 * whitelist: str, A string containing allowed characters for the value
 * blacklist: str, A string containing forbidden characters for the value
 * pattern: str, A regex pattern to test for string matches
+* func: Callable, A function containing a fully customized logic to validate the value
 
 `File` has the following options:
 * content_types: array of strings, an array of allowed content types.

flask_parameter_validation/parameter_types/parameter.py

@@ -1,6 +1,6 @@
 """
     Base Parameter class.
-    Should only be used as child class for othe params.
+    Should only be used as child class for other params.
 """
 import re
 
@@ -20,6 +20,7 @@ def __init__(
         whitelist=None,  # str: character whitelist
         blacklist=None,  # str: character blacklist
         pattern=None,  # str: regexp pattern
+        func=None,  # Callable: function performing a fully customized validation
     ):
         self.default = default
         self.min_list_length = min_list_length
@@ -31,6 +32,7 @@ def __init__(
         self.whitelist = whitelist
         self.blacklist = blacklist
         self.pattern = pattern
+        self.func = func
 
     # Validator
     def validate(self, value):
@@ -99,6 +101,13 @@ def validate(self, value):
                         f"pattern does not match: {self.pattern}."
                     )
 
+            # Callable
+            if self.func is not None:
+                if not self.func(value):
+                    raise ValueError(
+                        f"value does not match the validator function."
+                    )
+
         return True
 
     def convert(self, value, allowed_types):

setup.py

@@ -11,7 +11,7 @@
 
 setup(
     name='Flask-Parameter-Validation',
-    version='2.0.6',
+    version='2.1.0',
     url='https://github.com/Ge0rg3/flask-parameter-validation',
     license='MIT',
     author='George Omnet',