CODEWITHSUNDEEP
pythongoogle-app-engine
Saravanan
Saravanan

Reputation: 119

While retrieving image from datastore i am getting this error

I am new to google appengine.

I have stored the image in blob field. I am trying to get the image it shows error.

Below i have pasted my code and output.

main.py

import cgi 
import webapp2
from google.appengine.api import users
from google.appengine.ext.webapp.template \
    import render
from os import path
from google.appengine.ext import db
from google.appengine.api import images
import urllib
import re
import datetime



class imgstore(db.Model):
    name=db.StringProperty(multiline=True, default='')
    image=db.BlobProperty()


class MainHandler(webapp2.RequestHandler):
    def get(self):
        moviequery=db.GqlQuery('SELECT * FROM imgstore')
        context={
                'list':moviequery
                }   
        tmpl = path.join(path.dirname(__file__), 'static/html/index.html')
        self.response.out.write(render(tmpl, context))

    def post(self):
       name1 =images.resize(self.request.get("file"), 32, 32) 
       formdata = db.Blob(name1)
       insert = imgstore()
       insert.name="name"
       insert.image=formdata
       insert.put()


routes=[
        (r'/', MainHandler),
        ]
app = webapp2.WSGIApplication(routes=routes,debug=True)

index.html

> <html>
>     <head><title>test</title></head>
>     <body>hello
>        <form id="form" action="/" method="post" ENCTYPE="multipart/form-data">
>            <input type="file" name="file" >
>            <input type="submit" name="submit">
>        </form>
>        {% for lis in list%}
>        <img src="{{lis.image}}">
>        {% endfor %}
>     </body>
>         </html>

Output

Traceback (most recent call last):
  File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/lib/webapp2/webapp2.py", line 1536, in __call__
    rv = self.handle_exception(request, response, e)
  File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/lib/webapp2/webapp2.py", line 1530, in __call__
    rv = self.router.dispatch(request, response)
  File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/lib/webapp2/webapp2.py", line 1278, in default_dispatcher
    return route.handler_adapter(request, response)
  File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/lib/webapp2/webapp2.py", line 1102, in __call__
    return handler.dispatch()
  File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/lib/webapp2/webapp2.py", line 572, in dispatch
    return self.handle_exception(e, self.app.debug)
  File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/lib/webapp2/webapp2.py", line 570, in dispatch
    return method(*args, **kwargs)
  File "/Users/saravase/test/main.py", line 44, in get
    self.response.out.write(render(tmpl, context))
  File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/google/appengine/ext/webapp/template.py", line 92, in render
    return t.render(Context(template_dict))
  File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/google/appengine/ext/webapp/template.py", line 172, in wrap_render
    return orig_render(context)
  File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/google/appengine/_internal/django/template/__init__.py", line 173, in render
    return self._render(context)
  File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/google/appengine/_internal/django/template/__init__.py", line 167, in _render
    return self.nodelist.render(context)
  File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/google/appengine/_internal/django/template/__init__.py", line 794, in render
    bits.append(self.render_node(node, context))
  File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/google/appengine/_internal/django/template/__init__.py", line 807, in render_node
    return node.render(context)
  File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/google/appengine/_internal/django/template/defaulttags.py", line 173, in render
    nodelist.append(node.render(context))
  File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/google/appengine/_internal/django/template/__init__.py", line 847, in render
    return _render_value_in_context(output, context)
  File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/google/appengine/_internal/django/template/__init__.py", line 827, in _render_value_in_context
    value = force_unicode(value)
  File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/google/appengine/_internal/django/utils/encoding.py", line 88, in force_unicode
    raise DjangoUnicodeDecodeError(s, *e.args)
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Please guide me how to proceed further.

Upvotes: 1

Views: 682

Answers (1)

Adam Crossland
Adam Crossland

Reputation: 14213

You need to do two things. First, you need to change your HTML such that the src of the img tag contains a URL that is served by your application. Second, you need to implement a handler to server the URL.

Let's say that your application will serve stored images with a URL like this: /image/15 where 15 is the id of the imgstore entity. You'll need to add a route:

routes=[
        (r'/image/(\d+)', ImageHandler),
        (r'/', MainHandler),
        ]
app = webapp2.WSGIApplication(routes=routes,debug=True)

And then you'll need to add a new RequestHandler class:

class ImageHandler(webapp2.RequestHandler):
    def get(self, image_id):
        requestedImage = imgstore.get_by_id(int(image_id))
        if requestedImage is not None:
            self.response.out.write(requestedImage.image)
        else:
            # return a default image when we can't located the
            # one that was requested?

The new route includes a numeric capture -- (\d+) -- that will be passed to the request handler as a parameter. We can then use that id to get the image entity directly from the datastore; it's much faster than using a query.

So, where do we get the id from? Every entity in the datastore is automatically assigned an integer id unless you give it an id or a name when you store it.

The last thing that you need to do is provide an easy way to embed the URL that will server your image into the template that contains the img tag. Add a method to your imgstore class:

class imgstore(db.Model):
    name=db.StringProperty(multiline=True, default='')
    image=db.BlobProperty()

    def url_for(self):
        return "/image/%d" % self.id

Now you can change your template to use the new method:

<img src="{{lis.url_for}}">

Upvotes: 1

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