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How to delete an image using default_storage.delete(file_name) in Django View?

So I have been creating a Fingerprint Matching system using Django Rest Framework. Whenever I send a fingerprint from frontend to backend to match with the stored fingerprints. The fingerprint is getting stored there which is not what I want. I want to delete it once it's use is over.
Here is the Error Image: https://i.stack.imgur.com/MCXcv.png
def post(self, request, format = None):
serializer = serializers.MatchSerializer(data = request.data)
if serializer.is_valid():
#Fetching the stored fingerprints in a different serializer.
queryset = models.Profile.objects.all()
serializer2 = serializers.ProfileSerializer(queryset, many=True)
data = serializer2.data
#Initialized a result list which will be appended with the name of the user whose
#fingerprint is matched.
result = []
file = request.FILES['fingerprint']
file_name = default_storage.save(file.name, file)
file = default_storage.open(file_name)
file_url = default_storage.url(file_name)
fImage = cv2.imread(str(file))
for i in range(len(data)):
print(data[i].get('fingerprint'))
DbImage = cv2.imread('C:/Users/ShalomAlexander/Documents/4th Year
Project/Django/FingerprintMatch/' + data[i].get('fingerprint'))
if(isMatch(fImage, DbImage)):
result.append(data[i].get('name'))
#This is not working as expected because its raising an error ie. " Process is still
#in use"
default_storage.delete(file_name)
return Response(result)
If you have any better approach to match fingerprints or images that will also be appreciated. Thanks in advance. The current code works fine and matches the fingerprint as expected but its storing the incoming fingerprint image and I don't want that.

For me this problem was solved using file_path instead of file_name:
file_name = default_storage.save(file.name, file)
file_path = os.path.join(settings.MEDIA_ROOT, file_name)
. . .
default_storage.delete(file_path)

file = default_storage.open(file_name)
...
default_storage.delete(file_name)
That is why that file is open when you try to delete it.
This has nothing to do with OpenCV. The point of a minimal reproducible example is to make you figure out where the issue is.

It looks like more an opencv issue than django-rest-framework's one.
Please refer to this issue:
https://github.com/opencv/opencv/issues/12342
Looks like your solution might be just to upgrade your opencv package version.

python self.session doesn't save data correctly

I'm developing a webapp using Google App Engine and Python.
I'm facing a strange problem and i don't know how to solve it and what causes it.
When I fill a form I send the data for checking them. If they aren't complete and some fields are missed the server send the form back with an advice "FILL ALL THE FIELDS!".
That's work pretty well.
What I'm trying to do is sending the form back with the "description" and "title" fields filled with what the user has written before submitting the form, so he must to fill only the unfilled fields (and he doesn't need to rewrite everything from the beginning).
That's the code:
class SaleAnnCheck(BaseHandler):
def post(self):
title = self.request.POST.get('title')
cat = self.request.POST.get('cat')
description = self.request.POST.get('description')
AcqOpt = self.request.POST.get('AcqOpt')
lat = self.request.POST.get('lat')
lng = self.request.POST.get('lng')
image1 = self.request.POST.get("file1", None)
image2 = self.request.POST.get("file2", None)
image3 = self.request.POST.get("file3", None)
logging.info("info sale announcment")
logging.info(title)
logging.info(cat)
logging.info(description)
logging.info(AcqOpt)
logging.info(lat)
logging.info(lng)
logging.info(image1)
logging.info(image2)
logging.info(image3)
self.session["ECommerceUser"]["description"]=description
self.session["ECommerceUser"]["title"]=title
logging.info('session')
logging.info(self.session["ECommerceUser"])
if title == '' or cat == None or description == '' or AcqOpt == None or lat == '' or lng == '':
error = 'empty'
urlR='/CreateSaleAnn?'+urllib.urlencode({'error':'empty'})
self.redirect(urlR)
class Create(BaseHandler):
def get(self):
error = self.request.get('error')
if error == 'empty':
logging.info('sbagliato')
logging.info(self.session["ECommerceUser"])
template = JINJA_ENVIRONMENT.get_template('templates/CreateAnnouncement.html')
w = self.response.write
w(template.render({'error':'FILL ALL THE MANDATORY FIELDS!', 'description': self.session["ECommerceUser"]["description"], 'title': self.session["ECommerceUser"]["title"]}))
else:
logging.info('giusto')
logging.info(self.session["ECommerceUser"])
template = JINJA_ENVIRONMENT.get_template('templates/CreateAnnouncement.html')
w = self.response.write
w(template.render({'description': self.session["ECommerceUser"]["description"], 'title': self.session["ECommerceUser"]["title"]}))
When I submit the form the content is checked by making an HTTP post request to a certain URL, handled by SaleAnnCheck.
Description and Title are saved in the session correctly (i checked it by printing the content of self.session["ECommerceUser"] in the logs). Then, if a field isn't filled, the server redirect again to the form page, by a GET request to a related URL.
The requests to that URL is handled by Create. But when i try to render the HTML template of the form (using jinja2) with the previous typed values of Description and Title the related text areas are not filled with that values.
It happens because self.session["ECommerceUser"]["description"] and self.session["ECommerceUser"]["title"] are empty, but they weren't when i checked them before (in SaleAnnCheck).
Why it happens? Any explanation? It's a weird problem and there aren't any tips or suggestion about on internet

This is because 'self.session' is not a Session, it's just a class variable and will not be readable outside the class. If you really want to use persistent sessions for storing variables, try something like this:
From the docs:
http://docs.python-requests.org/en/master/user/advanced/
s = requests.Session()
s.get('http://httpbin.org/cookies/set/sessioncookie/123456789')
r = s.get('http://httpbin.org/cookies')

Image Thumbnail in Web2py: Unable to display the thumbnail

I have used the suggestion here http://www.web2pyslices.com/slice/show/1387/upload-image-and-make-a-thumbnail
to make a thumbnail of an image.
I have got the thumbnail but I am unable to display it.
The following are my functions:
db.py :
db.define_table('uploads', Field('dataset', 'reference dataset'),
Field('filename', represent = lambda x, row: "None" if x == None else [:45]),
Field('image', 'upload', uploadseparate=True, requires=IS_NOT_EMPTY() and IS_IMAGE(extensions=('jpeg', 'png','jpg','tif')) ),
Field('thumb', 'upload', uploadseparate=True, requires=IS_NOT_EMPTY() and IS_IMAGE(extensions=('jpeg', 'png', 'jpg', 'tif'))))
default.py :
def makeThumbnail(dbtable,ImageID,size=(150,150)):
try:
thisImage=db(dbtable.id==ImageID).select()[0]
import os, uuid
from PIL import Image
except: return
im=Image.open(request.folder + 'uploads/' + thisImage.image)
im.thumbnail(size,Image.ANTIALIAS)
thumbName='uploads.thumb.%s.jpg' % (uuid.uuid4())
im.save(request.folder + 'uploads/' + thumbName,'jpeg')
thisImage.update_record(thumb=thumbName)
return
def insertImage():
response.menu = [
(T('Home'),False,URL('default','experimenter')),
(T('Manage Data Set'),False,URL('default','MDS')),
(T('Manage Experiment'),False,URL('default','ME')),
(T('Manage Workflow Element'),False,URL('default','MWE'))]
dbtable = db.uploads
record = None
record = db(db.dataset.id == request.args[0],ignore_common_filters=True).select().first()
form = FORM(dbtable, INPUT(_name='up_files', _type='file',
_multiple=True, requires=IS_NOT_EMPTY()),INPUT(_type='submit'))
# The multiple param lets us choose multiple files.
if form.process().accepted:
#onvalidation checks the uploaded files to make sure they are only txt, config, or log.
makeThumbnail(dbtable,form.vars.id,(300,300))
response.flash = 'files uploaded'
files = request.vars['up_files']
if not isinstance(files, list):
#convert files to a list if they are not one already.
files = [files]
for file in files:
db.uploads.insert(dataset=record.id, filename=file.filename, image=db.uploads.image.store(file, file.filename))
#store is a FIELD method that let's you save a file to disk. you can choose the directory if you want using the 'path' param.
else:
response.flash = 'Choose the Files you would like to upload'
return dict(form=form, record=record)
And then the view:
{{extend 'layout.html'}}
<h4>Manage Image of dataset: {{=record.name}}</h4>
{{if images:}}
<div style="overflow: auto;" width="80%">
<table>
<tr> <th> Image </th> </tr>
{{
for image in images:
=TR(TD(image.filename), IMG(_src=URL('default', 'download', args=image.thumb)), A(str(T('View')),_href=URL("show", args=[image.id,rowId])), A(str(T('Delete')),_href=URL('deleteImage',args=image.id)))}}
{{pass}}
</table>
</div>
{{pass}}
Note: I am trying to display the the thumbnails for a each image in a list of images.(see the View).
I am not getting the thumbnail but rather small question marks in its place.
PS: i am unable to upload the image.
I want images in place of question mark. I am doing something wrong in insertImage() function and also in the view.
Thanks in Advance for the help!

First, you appear to be conflating FORM and SQLFORM. The former is for creating custom forms (not connected with any database tables), and the latter is for building a form based on a database table (and therefore automatically handling inserts). You cannot pass a DAL Table object to FORM as in your code -- that will simply serialize the Table object to its string name, which will be included in the HTML form DOM to no effect. Further, in this case, form.vars.id will simply be None (FORM does not generate record IDs, as it does not do any database inserts).
Also, rather than directly saving the file in makeThumbnail, a better option would be to save the image to a StringIO object and then pass that object to db.uploads.thumbnail.store() (as you do for storing the original image). In that case, the .store() method of the thumbnail field will handle the file naming and saving automatically.
from cStringIO import StringIO
tmp = StringIO()
im.save(tmp, 'jpeg')
tmp.seek(0)
thisImage.update_record(thumb=db.uploads.thumb.store(tmp, filename='thumbnail.jpg'))
For more details, see http://web2py.com/books/default/chapter/29/06/the-database-abstraction-layer.

How to put css files to head by means UIModule in the tornado?

I want to add set of css files to head. For instance,
python file:
modules.py
class SomeModule(tornado.web.UIModule):
def css_files(self):
return [self.handler.static_url('css/modules/some-module.css'),]
def render(self, some_data=None):
result = ''
if some_data is not None:
"""to do something with data"""
return result
server.py
app = Application(
...
ui_module=modules
...
)
template file:
...
{% module SomeModule(some_data=put_data_here) %}
As the result, I see only data that were returned from render. But css files weren't set between head tags.

What's the result of the template file depends on how you generate the template file. As far as I can see, you didn't include the code for that in your question.
If you want to use css_files() or similar, you need to use self.render_string() in order to give Tornado a chance to insert the CSS tags in the proper places.
For an example of how to use tornado.web.UIModule, see this Slideshare presentation

Performing text processing on flatpage content to include handling of custom tag

I'm using flatpages app in my project to manage some html content. That content will include images, so I've made a ContentImage model allowing user to upload images using admin panel.
The user should then be able to include those images in content of the flatpages. He can of course do that by manually typing image url into <img> tag, but that's not what I'm looking for.
To make including images more convenient, I'm thinking about something like this:
User edits an additional, let's say pre_content field of CustomFlatPage model (I'm using custom flatpage model already)
instead of defining <img> tags directly, he uses a custom tag, something like [img=...] where ... is name of the ContentImage instance
now the hardest part: before CustomFlatPage is saved, pre_content field is checked for all [img=...] occurences and they are processed like this:
ContentImage model is searched if there's image instance with given name and if so, [img=...] is replaced with proper <img> tag.
flatpage actual content is filled with processed pre_content and then flatpage is saved (pre_content is leaved unchanged, as edited by user)
The part that I can't cope with is text processing. Should I use regular expressions? Apparently they can be slow for large strings.
And how to organize logic? I assume it's rather algorithmic question, but I'm not familliar with text processing in Python enough, to do it myself.
Can somebody give me any clues?

I finally imlemented this using regular expressions. I decided, that spaces are not allowed inside the custom tag. Main text processing function looks like this:
import re
from django.utils.translation import ugettext as _
def process_image_tags(text, ImageModel):
'''image tag usage:
... some text ... [img=image_name:image_class(optional)] ... some text ...
'''
t1 = re.split(r'(\[img=[a-z0-9\-_\:]+\])', text)
t2 = []
for i in t1:
if i[:5] == '[img=':
attrs = i[5:-1].split(':')
name_attr = attrs[0] #name attribute
error = None
try:
image = ImageModel.objects.get(name=name_attr)
except ImageModel.DoesNotExist:
error = '<span class="image_tag_error">%s</span>' % _('Image with given name not found')
except ImageModel.MultipleObjectsReturned:
error = '<span class="image_tag_error">%s</span>' % _('More than one image found')
if not error:
p = ['<img']
p.append('src="%s"' % image.image.url)
if len(attrs) > 1:
p.append('class="%s"' % attrs[1]) #class attribute
if image.description:
p.append('title="%s"' % image.description)
p.append('alt="%s"' % image.name)
p.append('/>')
t2.append(' '.join(p))
else:
t2.append(error)
else:
t2.append(i)
return ''.join(t2)
Above function is then used in save method of CustomFlatPage model, like this:
def save(self, *args, **kwargs):
self.content = process_image_tags(self.pre_content, ContentImage)
super(CustomFlatPage, self).save(*args, **kwargs)
It seems to work, so I'll probably end up using that solution. Maybe I'll add some javascript for user to insert image tags by picking images from generated list of images, but even now it's better than manually typing urls, I think.