hide bottom space for error message when validation is None (#3660)

nicegui/elements/input.py

@@ -46,7 +46,7 @@ class Input(ValidationElement, DisableableElement, component='input.js'):
         :param password_toggle_button: whether to show a button to toggle the password visibility (default: False)
         :param on_change: callback to execute when the value changes
         :param autocomplete: optional list of strings for autocompletion
-        :param validation: dictionary of validation rules or a callable that returns an optional error message
+        :param validation: dictionary of validation rules or a callable that returns an optional error message (default: None for no validation)
         """
         super().__init__(value=value, on_value_change=on_change, validation=validation)
         if label is not None:

nicegui/elements/mixins/validation_element.py

@@ -8,11 +8,25 @@ from .value_element import ValueElement
 class ValidationElement(ValueElement):
 
     def __init__(self, validation: Optional[Union[Callable[..., Optional[str]], Dict[str, Callable[..., bool]]]], **kwargs: Any) -> None:
-        self.validation = validation if validation is not None else {}
+        self._validation = validation
         self._auto_validation = True
         self._error: Optional[str] = None
         super().__init__(**kwargs)
-        self._props['error'] = False  # NOTE: reserve bottom space for error message
+        self._props['error'] = None if validation is None else False  # NOTE: reserve bottom space for error message
+
+    @property
+    def validation(self) -> Optional[Union[Callable[..., Optional[str]], Dict[str, Callable[..., bool]]]]:
+        """The validation function or dictionary of validation functions."""
+        return self._validation
+
+    @validation.setter
+    def validation(self, validation: Optional[Union[Callable[..., Optional[str]], Dict[str, Callable[..., bool]]]]) -> None:
+        """Sets the validation function or dictionary of validation functions.
+
+        :param validation: validation function or dictionary of validation functions (``None`` to disable validation)
+        """
+        self._validation = validation
+        self.validate()
 
     @property
     def error(self) -> Optional[str]:
@@ -25,10 +39,11 @@ class ValidationElement(ValueElement):
 
         :param error: The optional error message
         """
-        if self._error == error:
+        new_error_prop = None if self.validation is None else (error is not None)
+        if self._error == error and self._props['error'] == new_error_prop:
             return
         self._error = error
-        self._props['error'] = error is not None
+        self._props['error'] = new_error_prop
         self._props['error-message'] = error
         self.update()
 
@@ -37,14 +52,15 @@ class ValidationElement(ValueElement):
 
         :return: True if the value is valid, False otherwise
         """
-        if callable(self.validation):
-            self.error = self.validation(self.value)
+        if callable(self._validation):
+            self.error = self._validation(self.value)
             return self.error is None
 
-        for message, check in self.validation.items():
-            if not check(self.value):
-                self.error = message
-                return False
+        if isinstance(self._validation, dict):
+            for message, check in self._validation.items():
+                if not check(self.value):
+                    self.error = message
+                    return False
 
         self.error = None
         return True

nicegui/elements/number.py

@@ -43,7 +43,7 @@ class Number(ValidationElement, DisableableElement):
         :param suffix: a suffix to append to the displayed value
         :param format: a string like "%.2f" to format the displayed value
         :param on_change: callback to execute when the value changes
-        :param validation: dictionary of validation rules or a callable that returns an optional error message
+        :param validation: dictionary of validation rules or a callable that returns an optional error message (default: None for no validation)
         """
         self.format = format
         super().__init__(tag='q-input', value=value, on_value_change=on_change, validation=validation)

nicegui/elements/select.py

@@ -49,7 +49,7 @@ class Select(ValidationElement, ChoiceElement, DisableableElement, component='se
         :param new_value_mode: handle new values from user input (default: None, i.e. no new values)
         :param multiple: whether to allow multiple selections
         :param clearable: whether to add a button to clear the selection
-        :param validation: dictionary of validation rules or a callable that returns an optional error message
+        :param validation: dictionary of validation rules or a callable that returns an optional error message (default: None for no validation)
         :param key_generator: a callback or iterator to generate a dictionary key for new values
         """
         self.multiple = multiple

nicegui/elements/textarea.py

@@ -27,7 +27,7 @@ class Textarea(Input, component='input.js'):
         :param placeholder: text to show if no value is entered
         :param value: the initial value of the field
         :param on_change: callback to execute when the value changes
-        :param validation: dictionary of validation rules or a callable that returns an optional error message
+        :param validation: dictionary of validation rules or a callable that returns an optional error message (default: None for no validation)
         """
         super().__init__(label, placeholder=placeholder, value=value, on_change=on_change, validation=validation)
         self._props['type'] = 'textarea'