Prevent django admin from escaping html

As of Django 1.9, you can use format_html(), format_html_join(), or allow_tags in your method. See the list_display docs for more info.

The code in the question using mark_safe will work. However a better option for methods like these might be format_html, which will escape arguments.

def _get_thumbnail(self, obj):    return format_html(u'<img src="{}" />', obj.admin_thumbnail.url)

In earlier versions of Django, using mark_safe() would not work, and Django would escape the output. The solution was to give the method an allow_tags attribute with the value set to True.

class PhotoAdmin(admin.ModelAdmin):    fields = ('title', 'image',)    list_display = ('title', '_get_thumbnail',)    def _get_thumbnail(self, obj):         return u'<img src="%s" />' % obj.admin_thumbnail.url    _get_thumbnail.allow_tags = True

I know this is a rather late answer, but I thought a more complete implementation would be helpful to others...

If you don't have it already with django-filer, get easy_thumbnails pip install easy-thumbnails.

# -*- coding: utf-8 -*-from django.contrib import adminfrom easy_thumbnails.files import get_thumbnailerfrom models import Photoclass PhotoAdmin(admin.ModelAdmin):    list_display = ('_thumbnail', 'title', )    list_display_links = ('_thumbnail', 'title', )  # This makes the icon clickable too    readonly_fields = ('_thumbnail', )    fields = ('title', 'photo', )    def _thumbnail(self, obj):        if obj.photo:            thumbnailer = get_thumbnailer(obj.photo)            thumb = thumbnailer.get_thumbnail({                'crop': True,                'size': (50, 50),                # Sharpen it up a little, since its so small...                'detail': True,                # Put other options here...            })            # Note: we get the actual width/height rather than            # hard-coding 50, 50, just to be DRYer            return u'<img src="%s" alt="thumbnail: %s" width="%d" height="%d"/>' % (thumb.url, obj.photo.name, thumb.width, thumb.height)        else:            return "[No Image]"    # Optional, Provide a nicer label in the display    _thumbnail.short_description = 'Thumbnail'    # Required, leaves the markup un-escaped    _thumbnail.allow_tags = Trueadmin.site.register(Photo, PhotoAdmin)