python - 如何在GAE数据存储中显示图像？

Question

我阅读了教程以及我能找到的有关显示数据存储中保存的图像的所有资源，但仍然无法使其工作。我很感激任何帮助。 This is my previous question .

下面的 /displayimage 代码显示了图像的损坏链接；对于 /image ，它给出 BadKeyError: Invalid string key 。 根据 Nick Johnson reply here我必须为 img_id 传递一个空字符串，但 /display image 中的logging.info 显示此键:(((result.key():))) ) agpkZXZ-dGluZy0xcg8LEghIb21lUGFnZRjOCAw。感谢您的帮助。

class HomePage(db.Model):
    thumbnail = db.BlobProperty()
    firm_name = db.StringProperty()

class ImageUpload(webapp.RequestHandler):
    def get(self):
...        
        self.response.out.write("""
        <form action="/imagesave" enctype="multipart/form-data" method="post">
        <div><label>firm name:</label> <input type="text" name="firm_name" size=40></div>
        <div><input type="file" name="img" /></div>
        <div><input type="submit" value="Upload image"></div>
        </form>
        """)

class ImageSave(webapp.RequestHandler):
    def post(self):
        homepage = HomePage()
        thumbnail = self.request.get("img")
        firm_name = self.request.get("firm_name")
        homepage.thumbnail = db.Blob(thumbnail)
        homepage.firm_name = firm_name
        homepage.put()

        self.redirect("/imageupload")

class ImageResize(webapp.RequestHandler):
    def post(self):
        q = HomepageImage.all()
        q.filter("firm_name", "mta")
        qTable = q.get()

        if qTable:
            qTable.thumbnail = db.Blob(images.resize(self.request.get("img"), 32, 32))
            db.put(qTable)
        else:
            self.response.out.write("""firm not found""")
        self.redirect("/imageupload")

class DisplayImage(webapp.RequestHandler):
    def get(self):
...
        query = HomePage.all()
        query.filter("firm_name", "mta")
        result = query.get()

        self.response.out.write("""firm name: %s""" % result.firm_name)

        #self.response.out.write("""<img src="img?img_id=%s"></img>""" %
        #chenged this line as systempuntoout's comment to:
        self.response.out.write("""<img src="/image?img_id=%s"></img>""" %
        result.key())
        #but I still get the same error
class Image(webapp.RequestHandler):
    def get(self):
...
    #I am adding the next line to show that "img_id" is an empty string.
    #why "img_id" empty here?

    img_id = self.request.get("img_id")
    logging.info("""**************************img_id: %s**************************""" % img_id)
    #**************************img_id: **************************

        homepage = db.get(self.request.get("img_id"))

        if homepage.thumbnail:
            self.response.headers['Content-Type'] = "image/jpg"
            self.response.out.write(homepage.thumbnail)
        else:
            self.response.out.write("no image")


application = webapp.WSGIApplication(
[
("/imageresize",ImageResize),
("/imageupload", ImageUpload),
("/displayimage", DisplayImage),
("/imagesave", ImageSave),
("/image", Image),
],                                      
debug=True
)

def main():
    run_wsgi_app(application)
if __name__ == "__main__":
    main()

Answer 1

您将图像源指向未定义的错误 img 路由。
正确的链接应该指向 /image，如下所示:

<img src="/image?img_id=%s"></img>

我已经通过更正测试了您的代码，它运行良好:

from google.appengine.ext import db
from google.appengine.api import users
from google.appengine.ext import webapp
from google.appengine.ext.webapp.util import run_wsgi_app
import logging


class HomePage(db.Model):
    thumbnail = db.BlobProperty()
    firm_name = db.StringProperty()

class ImageUpload(webapp.RequestHandler):
    def get(self):
        self.response.out.write("""
        <form action="/imagesave" enctype="multipart/form-data" method="post">
        <div><label>firm name:</label> <input type="text" name="firm_name" size=40></div>
        <div><input type="file" name="img" /></div>
        <div><input type="submit" value="Upload image"></div>
        </form>
        """)

class ImageSave(webapp.RequestHandler):
    def post(self):
        homepage = HomePage()
        thumbnail = self.request.get("img")
        firm_name = self.request.get("firm_name")
        homepage.thumbnail = db.Blob(thumbnail)
        homepage.firm_name = firm_name
        homepage.put()
        self.redirect("/imageupload")

class ImageResize(webapp.RequestHandler):
    def post(self):
        q = HomepageImage.all()
        q.filter("firm_name", "mta")
        qTable = q.get()
        if qTable:
            qTable.thumbnail = db.Blob(images.resize(self.request.get("img"), 32, 32))
            db.put(qTable)
        else:
            self.response.out.write("""firm not found""")
        self.redirect("/imageupload")

class DisplayImage(webapp.RequestHandler):
    def get(self):
        query = HomePage.all()
        query.filter("firm_name", "mta")
        result = query.get()
        self.response.out.write("""firm name: %s""" % result.firm_name)
        self.response.out.write("""<img src="/image?img_id=%s"></img>""" %
        result.key())

class Image(webapp.RequestHandler):
    def get(self):
        img_id = self.request.get("img_id")
        logging.info("""**************************img_id: %s**************************""" % img_id)
        homepage = db.get(self.request.get("img_id"))
        if homepage.thumbnail:
                self.response.headers['Content-Type'] = "image/jpg"
                self.response.out.write(homepage.thumbnail)
        else:
                self.response.out.write("no image")


application = webapp.WSGIApplication(
[
("/imageresize",ImageResize),
("/imageupload", ImageUpload),
("/displayimage", DisplayImage),
("/imagesave", ImageSave),
("/image", Image),
],                                      
debug=True
)

def main():
    run_wsgi_app(application)
if __name__ == "__main__":
    main()