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,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)