from sqlalchemy import types
from ..exceptions import ImproperlyConfigured
from .scalar_coercible import ScalarCoercible
colour = None
try:
import colour
python_colour_type = colour.Color
except (ImportError, AttributeError):
python_colour_type = None
[docs]class ColorType(ScalarCoercible, types.TypeDecorator):
"""
ColorType provides a way for saving Color (from colour_ package) objects
into database. ColorType saves Color objects as strings on the way in and
converts them back to objects when querying the database.
::
from colour import Color
from sqlalchemy_utils import ColorType
class Document(Base):
__tablename__ = 'document'
id = sa.Column(sa.Integer, autoincrement=True)
name = sa.Column(sa.Unicode(50))
background_color = sa.Column(ColorType)
document = Document()
document.background_color = Color('#F5F5F5')
session.commit()
Querying the database returns Color objects:
::
document = session.query(Document).first()
document.background_color.hex
# '#f5f5f5'
.. _colour: https://github.com/vaab/colour
"""
STORE_FORMAT = 'hex'
impl = types.Unicode(20)
python_type = python_colour_type
cache_ok = True
def __init__(self, max_length=20, *args, **kwargs):
# Fail if colour is not found.
if colour is None:
raise ImproperlyConfigured(
"'colour' package is required to use 'ColorType'"
)
super().__init__(*args, **kwargs)
self.impl = types.Unicode(max_length)
def process_bind_param(self, value, dialect):
if value and isinstance(value, colour.Color):
return str(getattr(value, self.STORE_FORMAT))
return value
def process_result_value(self, value, dialect):
if value:
return colour.Color(value)
return value
def _coerce(self, value):
if value is not None and not isinstance(value, colour.Color):
return colour.Color(value)
return value