I've been checking the documentation example about how to manioulate
images in GAE, and I decided to translate the sample from webapp to
webpy ( the sample is here:
http://code.google.com/appengine/docs/images/usingimages.html
).
The problem is that I cannot find the way to display properly the
images stored in the datastore.
The weapp sample creates a handler for displaying the image as
follows:
class Image (webapp.RequestHandler):
def get(self):
greeting = db.get(self.request.get("img_id"))
if greeting.avatar:
self.response.headers['Content-Type'] = "image/png"
self.response.out.write(greeting.avatar)
else:
self.error(404)
And then, in the main handler, the images are displayed as follows
(simplified):
...
for greeting in greetings:
self.response.out.write("<div><img src='img?img_id=%s'></img>" %
greeting.key())
self.response.out.write(' %s</div>' %
cgi.escape(greeting.content))
...
Problems:
webapp outputs resullts with "self.response.out.write" which is
equivalent to a "print" statement, while webpy does it with "return".
I tried adding strings to a list and then return all as
''.join(mylist), as usual, but the image is not displayed.
I also tried requesting directly the Image handler and it doesn't
work.
I also tried using "yield" instead, with same result.
I believe that it has to do with mixing headers ("text/html" in main
handler and "image/png" in image handler) but I'm not sure.
I also tried a simple output of the image with an "image/png" header
and it doesn't work...
My translated script is this (using webpy version 0.3):
import web
from google.appengine.ext import db
from google.appengine.api import users
from google.appengine.api import images
app = web.auto_application()
class Greeting(db.Model):
author = db.UserProperty()
content = db.StringProperty(multiline=True)
avatar = db.BlobProperty()
date = db.DateTimeProperty(auto_now_add=True)
class index(app.page):
path = '/'
def GET(self):
web.header('Content-Type', "text/html")
greetings = db.GqlQuery ("SELECT * FROM Greeting ORDER BY date
DESC LIMIT 10")
s = []
for greeting in greetings:
if greeting.author:
s.append('<b>%s</b> wrote:' % greeting.author.nickname())
else:
s.append('An anonymous person wrote:')
s.append("<div><img src='img?img_id=%s'></img>" %greeting.key())
s.append('%s</div>' %greeting.content)
s.append("""
<form action="/sign" enctype="multipart/form-data"
method="POST">
<div><label>Message:</label></div>
<div><textarea name="content" rows="3" cols="60"></
textarea></div>
<div><label>Avatar:</label></div>
<div><input type="file" name="img"/></div>
<div><input type="submit" value="Sign Guestbook"></div>
</form>
</body>
</html>""")
return ''.join(s)
class img(app.page):
def GET(self, img_id):
greeting = db.get(img_id)
if greeting.avatar:
web.header('Content-Type', "image/png")
return greeting.avatar
else:
return "No image"
class sign(app.page):
def POST(self):
i = web.input()
greeting = Greeting()
if users.get_current_user():
greeting.author = users.get_current_user()
greeting.content = i.content
avatar = images.resize(i.img, 502, 502)
greeting.avatar = db.Blob(avatar)
greeting.put()
web.seeother('/')
def main():
app.cgirun()
if __name__=='__main__':
main()
Any hint?
Luis
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