我正在制作一个应用程序来上传文字和图片。我对blobstore和Google高性能图像服务有很多了解,最后我找到了一种方法来实现它。
我想知道的是,如果一切都做得好或可以更好的方式做,并且如果最好将serving_url保存在模型中,或者每次我想要打印图像时都必须计算页。
只有用户和图片。
这是代码(总结一下,忘了我的custom.PageHandler,它只有轻松渲染页面的函数,以及检查表单值的东西等):
class User(ndb.Model):
""" A User """
username = ndb.StringProperty(required=True)
password = ndb.StringProperty(required=True)
email = ndb.StringProperty(required=True)
class Picture(ndb.Model):
""" All pictures that a User has uploaded """
title = ndb.StringProperty(required=True)
description = ndb.StringProperty(required=True)
blobKey = ndb.BlobKeyProperty(required=True)
servingUrl = ndb.StringProperty()
created = ndb.DateTimeProperty(auto_now_add=True)
user = ndb.KeyProperty(kind=User)
# This class shows the user pics
class List(custom.PageHandler):
def get(self):
# Get the actual user pics
pics = Picture.by_user(self.user.key)
for pic in pics:
pic.servingUrl = images.get_serving_url(pic.blobKey, size=90, crop=True)
self.render_page("myPictures.htm", data=pics)
# Get and post for the send page
class Send(custom.PageHandler, blobstore_handlers.BlobstoreUploadHandler):
def get(self):
uploadUrl = blobstore.create_upload_url('/addPic')
self.render_page("addPicture.htm", form_action=uploadUrl)
def post(self):
# Create a dictionary with the values, we will need in case of error
templateValues = self.template_from_request()
# Test if all data form is valid
testErrors = check_fields(self)
if testErrors[0]:
# No errors, save the object
try:
# Get the file and upload it
uploadFiles = self.get_uploads('picture')
# Get the key returned from blobstore, for the first element
blobInfo = uploadFiles[0]
# Add the key to the template
templateValues['blobKey'] = blobInfo.key()
# Save all
pic = Picture.save(self.user.key, **templateValues)
if pic is None:
logging.error('Picture save error.')
self.redirect("/myPics")
except:
self.render_page("customMessage.htm", custom_msg=_("Problems while uploading the picture."))
else:
# Errors, render the page again, with the values, and showing the errors
templateValues = custom.prepare_errors(templateValues, testErrors[1])
# The session for upload a file must be new every reload page
templateValues['form_action'] = blobstore.create_upload_url('/addPic')
self.render_page("addPicture.htm", **templateValues)
基本上,我列出了所有的照片,用这一行在jinja2模板中显示图像:
{% for line in data %}
<tr>
<td class="col-center-data"><img src="{{ line.servingUrl }}"></td>
因此,在List类中,我计算每个服务URL并将其临时添加到Model中。我不知道是否将它直接保存在模型中是好的,因为我不知道url是否随时间变化。将是图像永久的网址?在那种情况下,我可以保存而不是计算,是吗?
Send类仅显示上传图像的表单并将数据保存到Model。在重新呈现页面的情况下,我总是生成一个新的form_action链接,因为docs会谈论它。是不是?
代码正在运行,但我想知道在性能和资源节省方面哪种方式更好。
答案 0 :(得分:4)
请注意,当您完成网址时,会有一个delete_serving_url(),就像删除blob一样。