django自定义Field实现一个字段存储以逗号分隔的字符串

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)