如何在 GAE 数据存储中显示图像？

Question

我阅读了教程和所有我能找到的关于显示保存在数据存储中的图像的资源，但我仍然无法让它工作。我很感激任何帮助。 This is my previous question.

下面的代码，/displayimage 显示图像的链接断开；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 显示这个键：(((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>

我已经用我的修正测试了你的代码，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()