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InputFilter

Input filter prevents the insertion of characters matching (or not matching) a particular pattern(regex_string), by replacing the characters with the given replacement_string. When this parameter changes, the new filter will not be applied until the next time the user inserts or deletes text. Note that, similar to the on_change callback, the input filters are not applied when the text is changed programmatically.

InputFilter class takes 3 parameters:

  • regex_string: a regular expression pattern for the filter
  • allow: a boolean value indicating whether to allow or deny/block the matched patterns - default is True
  • replacement_string: string used to replace banned/denied patterns - default is an empty string.

The following helper classes are equally available:

  • NumbersOnlyInputFilter() - only allow numbers
  • TextOnlyInputFilter() - only allow text characters

Examples of usage:​

ft.CupertinoTextField(
    placeholder_text="Only numbers are allowed :)",
    input_filter=ft.InputFilter(allow=True, regex_string=r"[0-9]", replacement_string=""),
)
ft.TextField(
    label="Only numbers are allowed :)",
    input_filter=ft.InputFilter(allow=True, regex_string=r"[0-9]", replacement_string=""),
    # input_filter=ft.NumbersOnlyInputFilter()
)