rapid-django/src/rapid/rapidfields.py

# coding=utf-8

from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
from __future__ import unicode_literals

from django.contrib.contenttypes.fields import GenericForeignKey
from django.contrib.contenttypes.models import ContentType
from rapid.rapidforms import RapidAlternativesField
from django.db import models

__author__ = 'marcos'

"""
Model fields specific for Rapid Django.
"""


class AlternativeData(GenericForeignKey):
    """
    A generic relation that Rapid will display as an inline form or a group of data at the
     edit and view actions.

    Create like a Django GenericForeignKey, but use an AlternativeDataTables instead of a
    ForeignKey to ContentTypes.

    That is, a model becomes something like this:
    class MyModel(models.Model):
        alt_data_type = rapidfields.AlternativeDataTables((Model1, Model2))
        alt_data_id = models.PositiveIntegerField()
        alt_data = rapidfields.AlternativeData('alt_data_type', 'alt_data_id', verbose_name='fill either a model1 or
        a model2 object')

    In forms, Rapid will display a select widget with the options "model1" and "model2",
    and show the appropriate form after selected.
    """
    is_rapid_alternatives = True

    def __init__(self, *args, **kwargs):
        verbose_name = kwargs.get('verbose_name')
        if 'verbose_name' in kwargs:
            del(kwargs['verbose_name'])
        super(AlternativeData, self).__init__(*args, **kwargs)
        if verbose_name:
            self.verbose_name = verbose_name
        elif self.name:
            self.verbose_name = self.name.replace('_', ' ')

    def formfield(self, **kwargs):
        kwargs['form_class'] = RapidAlternativesField
        # noinspection PyUnresolvedReferences
        return super(GenericForeignKey, self).formfield(**kwargs)


class AlternativeDataTables(models.ForeignKey):
    """
    Use an AlternativeDataTables model field on AlternativeData representations, instead of
    a ForeignKey with ContentTypes.
    """
    is_rapid_alternatives = True

    def __init__(self, alternatives=(), **kwargs):
        """
        Receives the same named parameters of a ForeignKey, but instead of a target table,
        receives a list of the tables that may keep the alternative data.
        :param alternatives: List of the tables that hold the alternative data.
        :param kwargs: Arguments to the ForeignKey, without a relationship target.
        """
        pks = []
        try:
            pks = [ContentType.objects.get_for_model(a).pk for a in alternatives]
        except RuntimeError:
            # Querying ContentType within a content type is an issue at migrations
            pass
        kwargs['limit_choices_to'] = {'pk__in': pks}
        kwargs['to'] = ContentType
        super(AlternativeDataTables, self).__init__(**kwargs)
        self.alternatives = alternatives