实现了在一个字段存储以逗号分隔的字符串，返回一个相应的列表

复制代码 代码如下:
from django import forms
from django.db import models
from django.utils.text import capfirst
from django.core import exceptions

class MultiSelectFormField(forms.MultipleChoiceField):
    widget = forms.CheckboxSelectMultiple

    def __init__(self, *args, **kwargs):
        self.max_choices = kwargs.pop(\’max_choices\’, 0)
        super(MultiSelectFormField, self).__init__(*args, **kwargs)

    def clean(self, value):
        if not value and self.required:
            raise forms.ValidationError(self.error_messages[\’required\’])
        # if value and self.max_choices and len(value) > self.max_choices:
        #     raise forms.ValidationError(\’You must select a maximum of %s choice%s.\’
        #             % (apnumber(self.max_choices), pluralize(self.max_choices)))
        return value

class MultiSelectField(models.Field):
    __metaclass__ = models.SubfieldBase

    def get_internal_type(self):
        return \”CharField\”

    def get_choices_default(self):
        return self.get_choices(include_blank=False)

    def _get_FIELD_display(self, field):
        value = getattr(self, field.attname)
        choicedict = dict(field.choices)

    def formfield(self, **kwargs):
        # don\’t call super, as that overrides default widget if it has choices
        defaults = {\’required\’: not self.blank, \’label\’: capfirst(self.verbose_name),
                    \’help_text\’: self.help_text, \’choices\’: self.choices}
        if self.has_default():
            defaults[\’initial\’] = self.get_default()
        defaults.update(kwargs)
        return MultiSelectFormField(**defaults)

    def get_prep_value(self, value):
        return value

    def get_db_prep_value(self, value, connection=None, prepared=False):
        if isinstance(value, basestring):
            return value
        elif isinstance(value, list):
            return \”,\”.join(value)

    def to_python(self, value):
        if value is not None:
            return value if isinstance(value, list) else value.split(\’,\’)
        return \’\’

    def contribute_to_class(self, cls, name):
        super(MultiSelectField, self).contribute_to_class(cls, name)
        if self.choices:
            func = lambda self, fieldname = name, choicedict = dict(self.choices): \”,\”.join([choicedict.get(value, value) for value in getattr(self, fieldname)])
            setattr(cls, \’get_%s_display\’ % self.name, func)

    def validate(self, value, model_instance):
        arr_choices = self.get_choices_selected(self.get_choices_default())
        for opt_select in value:
            if (int(opt_select) not in arr_choices):  # the int() here is for comparing with integer choices
                raise exceptions.ValidationError(self.error_messages[\’invalid_choice\’] % value)
        return

    def get_choices_selected(self, arr_choices=\’\’):
        if not arr_choices:
            return False
        list = []
        for choice_selected in arr_choices:
            list.append(choice_selected[0])
        return list

    def value_to_string(self, obj):
        value = self._get_val_from_obj(obj)
        return self.get_db_prep_value(value)