Storing images in google datastore using Flask (Python)

Question

I am using flask on google app engine and am desperately looking for help to solve this. The GAE documentation talks of storing images in the datastore using the BlobProperty , which should be done something like this:-

class MyPics(db.Model):
      name=db.StringProperty()
      pic=db.BlobProperty()

Now the image should be stored in the datastore by doing this:-

def storeimage():
    pics=MyPics()
    pics.name=request.form['name']
    uploadedpic=request.files['file']  #where file is the fieldname in the form of the                
                                        file uploaded
    pics.pic=db.Blob(uploadedpic)
    pics.put()
    redirect ... etc etc

But am unable to do this. as I get db.Blob accepts a string , but given a Filestorage object... Can someone help me with this. Also if anybody could hint me on how to stream the image back after uploading.

please consider posting your solution and marking it as the answer. That way the question is officially answered :) — Wolph
– Wolph, Commented Nov 3, 2010 at 14:01

Rasmus · Accepted Answer · 2010-11-04 13:37:47Z

6

Ok so this is how I finally solved it:-

@userreg.route('/mypics',methods=['GET','POST'])
def mypics():    
   if request.method=='POST':
      mydata=MyPics()
      mydata.name=request.form['myname']
      file=request.files['file']
      filedata=file.read()
      if file:
         mydata.pic=db.Blob(filedata)
      mydata.put()
      return redirect(url_for('home'))
   return render_template('mypicform.html')

The above stores the file as a blob in the datastore and then it can be retrieved by the below func:-

@userreg.route('/pic/<name>')
def getpic(name):
     qu=db.Query(MyPics).filter('name =',name).get()
     if qu.pic is None:
         return "hello"
     else:
         mimetype = 'image/png'
         return current_app.response_class(qu.pic,mimetype=mimetype,direct_passthrough=False)

answered Nov 4, 2010 at 13:37

Rasmus

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Comments

Wolph · Accepted Answer · 2010-10-26 11:04:14Z

1

You should consider using the BlobStore to store your data. Instead of a db.Blob you would be using blobstore.BlobReferenceProperty: http://code.google.com/appengine/docs/python/datastore/typesandpropertyclasses.html#BlobReferenceProperty

Uploading and download is quite easy as shown here: http://code.google.com/appengine/docs/python/blobstore/overview.html#Complete_Sample_App

answered Oct 26, 2010 at 11:04

Wolph

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2 Comments

Rasmus Over a year ago

But for blobstore wont I have to activate the payment mechanism. As of now I am just developing, deploying, changing things, working on it etc etc.

Wolph Over a year ago

@Alice; Yes, that's true. Enabling billing doesn't automatically cost you money though, the default quotas allow even most small websites to run for free. If enabling payments is an option that that's what I'd suggest.

user957557 · Accepted Answer · 2011-11-04 14:26:44Z

I have following model

class Picture(db.Model):    
    data = db.BlobProperty()
    ext = db.StringProperty()
    content_type = db.StringProperty()

and store it using next code:

def create_picture():
    if request.files['file']:                       
        picture.data = request.files['file'].read()
        picture.ext = request.files['file'].filename.rsplit('.', 1)[1]
        picture.content_type = request.files['file'].content_type
        picture.put()
        flash(u'File uploaded', 'correct')
        return redirect(url_for("edit_picture", id=picture.key()))
    else:
        return render_template('admin/pictures/new.html', title=u'Upload a picture', message=u'No picture selected')

To render a thumbnail you can use next code:

@frontend.route('/thumbnail/<id>/<width>x<height>.<ext>')
def thumbnail(id, width, height, ext):
    key = db.Key(id)
    picture = Picture.get(key)
    img = images.Image(picture.data)

    if width != '0':
        w = int(width)
    else:
        w = img.width

    if height != '0':
        h = int(height)
    else:
        h = img.height

    if img.height > h and h != 0:
        w = (int(width) * img.width) / img.height;

    if img.width > w:
        h = (int(height)  * img.height) / img.width;

    thumb = images.resize(picture.data, width=w, height=h)    
    response = make_response(thumb)
    response.headers['Content-Type'] = picture.content_type
    return response

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