django 修改model field后台默认的显示方式

我们都知道django模型在后台有默认的显示方式，它的显示是靠widget(不了解widget参考:https://docs.djangoproject.com/en/dev/ref/forms/widgets/)这种方式,所以要修改feild的默认显示方式，需要自定义widget,下面是一个自定义ImageField的widget

django默认的ImageField在后台显示的是image的url，我们更希望看到image的thumbnail,那要怎么做呢：

1、model

class RecommendApp(models.Model):    slider_image=models.ImageField('幻灯截图',upload_to="slider",null=True,blank=True)

2、在widget.py中自定义imageWidget

#coding=utf8from django.forms.widgets import ClearableFileInput,CheckboxInputfrom django.utils.html import escape, conditional_escapefrom django.utils.encoding import StrAndUnicode, force_unicodefrom django.utils.safestring import mark_safeclass ImageWidget(ClearableFileInput):    def render(self, name, value, attrs=None):        substitutions = {            'initial_text': self.initial_text,            'input_text': self.input_text,            'clear_template': '',            'clear_checkbox_label': self.clear_checkbox_label,        }        template = u'%(input)s'        substitutions['input'] = super(ClearableFileInput, self).render(name, value, attrs)        if value and hasattr(value, "url"):            template = self.template_with_initial            substitutions['initial'] = (u'<a href="%s" target="_blank"><img width="100px" height="100px" src="%s"></a>'                                        % (escape(value.url),                                           escape(value.url)))            if not self.is_required:                checkbox_name = self.clear_checkbox_name(name)                checkbox_id = self.clear_checkbox_id(checkbox_name)                substitutions['clear_checkbox_name'] = conditional_escape(checkbox_name)                substitutions['clear_checkbox_id'] = conditional_escape(checkbox_id)                substitutions['clear'] = CheckboxInput().render(checkbox_name, False, attrs={'id': checkbox_id})                substitutions['clear_template'] = self.template_with_clear % substitutions        return mark_safe(template % substitutions)

3、在admin.py中添加自定义widget

class RecommendAppAdmin(admin.ModelAdmin):        def formfield_for_dbfield(self, db_field, **kwargs):        if db_field.name=='slider_image':            kwargs['widget']=ImageWidget            try:                del kwargs['request']            except KeyError:                pass            return db_field.formfield(**kwargs)        return super(RecommendAppAdmin, self).formfield_for_dbfield(db_field, **kwargs)admin.site.register(RecommendApp,RecommendAppAdmin);

通过上面这3步就能在后台看到image的缩略图了