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Asked: 2026-06-10T19:11:48+00:00

I am using Google App Engine with python 2.7 and Django templates. My object

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I am using Google App Engine with python 2.7 and Django templates.

My object model is set up like this:

Class parent(db.Model):
  parentName = db.StringProperty()

Class child(db.Mode):
  childName = db.StringProperty()
  parent = db.ReferenceProperty(parent, collection_name='children')

My python code passes all the parents to the template

qry_parents = parent.all()
parents = qry_parents.fetch(30)
template_values = {'parents':parents}

self.response.out.write(template.render(path, template_values))

Now, what I am trying to do, but can’t seem to figure out, is how to display a count of the children from the implied collection “children” in the parent object. Here is a sample of my template.html

<html>
<body>
  <table>
  {% for p in parents %}
    <tr>
      <td>{{ p.parentName }}</td>
      <td>{{ p.children.items|length }}</td> <!-- always zero! -->
    </tr>
  {% endfor %}
  </table>
</body>
</html>

I can’t seem to reference the right thing to get the count of children out of there. I feel like I’m close, because I’m getting zero, not None or null. Can someone point me in the right direction? Thanks much!

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1 Answer

  1. Editorial Team

    You don’t need items. children is a db.Query object already. You’re best off doing p.children.count though.

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