CSS Color Validator for Django models and forms

validators.py

import re
from django.core.exceptions import ValidationError


def validate_css_color(value):
    """
    Custom validation function for background color field.

    Args:
        value (str): The value entered for the background color field.

    Returns:
        str: The cleaned value (if valid color) or raises a ValidationError.
    """
    # Regexes for different color formats
    hex_regex = r"^#[0-9a-fA-F]{3}$|^#[0-9a-fA-F]{6}$|^#[0-9a-fA-F]{8}$"
    rgb_regex = r"^rgb\(\s*(?:\d{1,3}\s+|\d{1,3})\s*(?:,\s+|\s+)(?:\d{1,3}\s+|\d{1,3})\s*(?:,\s+|\s+)\d{1,3}\s*\)$"
    rgba_regex = r"^rgba\(\s*(?:\d{1,3}\s+|\d{1,3})\s*(?:,\s+|\s+)(?:\d{1,3}\s+|\d{1,3})\s*(?:,\s+|\s+)(?:\d{1,3}\s+|\d{1,3})\s*(?:,\s*0?\.\d+|\d)(?:,\s*0?\.\d+|\d)?\s*\)$"
    hsla_regex = r"^hsla\(\s*(?:\d{1,3}|\d{0,2}\.\d{1,3})?\s*,\s*\d{1,3}\%?\s*,\s*\d{1,3}\%?\s*(?:,\s*0?\.\d+|\d)?\s*\)$"
    named_color_regex = r"^(yellowgreen|yellow|whitesmoke|white|wheat|violet|turquoise|transparent|tomato|thistle|teal|tan|steelblue|springgreen|snow|slategrey|slategray|slateblue|skyblue|silver|sienna|seashell|seagreen|sandybrown|salmon|saddlebrown|royalblue|rosybrown|red|rebeccapurple|purple|powderblue|plum|pink|peru|peachpuff|papayawhip|palevioletred|paleturquoise|palegreen|palegoldenrod|orchid|orangered|orange|olivedrab|olive|oldlace|navy|navajowhite|moccasin|mistyrose|mintcream|midnightblue|mediumvioletred|mediumturquoise|mediumspringgreen|mediumslateblue|mediumseagreen|mediumpurple|mediumorchid|mediumblue|mediumaquamarine|maroon|magenta|linen|limegreen|lime|lightyellow|lightsteelblue|lightslategrey|lightslategray|lightskyblue|lightseagreen|lightsalmon|lightpink|lightgrey|lightgreen|lightgray|lightgoldenrodyellow|lightcyan|lightcoral|lightblue|lemonchiffon|lawngreen|lavenderblush|lavender|khaki|ivory|indigo|indianred|hotpink|honeydew|grey|greenyellow|green|gray|goldenrod|gold|ghostwhite|gainsboro|fuchsia|forestgreen|floralwhite|firebrick|dodgerblue|dimgrey|dimgray|deepskyblue|deeppink|darkviolet|darkturquoise|darkslategrey|darkslategray|darkslateblue|darkseagreen|darksalmon|darkred|darkorchid|darkorange|darkolivegreen|darkmagenta|darkkhaki|darkgrey|darkgreen|darkgray|darkgoldenrod|darkcyan|darkblue|cyan|crimson|cornsilk|cornflowerblue|coral|chocolate|chartreuse|cadetblue|burlywood|brown|blueviolet|blue|blanchedalmond|black|bisque|beige|azure|aquamarine|aqua|antiquewhite|aliceblue)$"

    # Check for valid hex color
    if re.match(hex_regex, value):
        return value.upper()

    # Check for RGB or RGBA color
    elif re.match(rgb_regex, value) or re.match(rgba_regex, value) or re.match(hsla_regex, value):
        return value.lower()

    # Check for named color (using predefined list)
    elif re.match(named_color_regex, value):
        return value.lower()

    # If none of the above matches, raise a validation error
    else:
        raise ValidationError(
            "Invalid color format. Please use a valid hex, rgb(a), hsl(a), or named color."
        )