什么是空白的GQL结果？ [英] What Does a Blank GQL Result Look Like?

问题描述

我正在研究Google App Engine应用程序，并且在使用GQL查询和if语句时遇到了一些问题。这是代码：

I am working on a Google App Engine application, and have been facing some issues with a GQL query and an if statement. This is the code:

q = Song.gql("WHERE title = :1", self.request.get('song_title'))
q.get()
  if q:
    r = "Excisting Results Found: <br />"
    print q
    for song in q:
      r += song.title+" by "+song.artist+"<br />"
    self.response.out.write(r)
  else: 
    ...

运行此操作时，页面会返回找到的已发现结果：但我知道实际上没有找到结果。有没有办法检查查询返回的结果是否为空？从 GqlQuery look 返回的空白结果是什么样的？

When this is run, the page returns "Excisting Results Found:" however I know that no results were in fact found. Is there a way to check if the results returned by the query are empty? What would a blank result returned from GqlQuery look like?

非常感谢，

谢谢。

Any help would be greatly appreciated,
Thanks.

推荐答案

在这个例子中，q是一个GQL查询对象。虽然你可以把它当作一个迭代对象，但是调用get（）会返回一个结果，并且你需要将这个结果赋值给一个变量。您也可以通过检查q.count（1）是否大于0来检查是否有结果。

In this example, q is a GQL query object. Although you can treat it as an iterable, calling get() on it will return a single result, and you'd need to assign this result to a variable. You can also check if there are results by checking if q.count(1) is greater than 0.

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