CODEWITHSUNDEEP
pythongoogle-app-engineapp-engine-ndb
Omair Shamshir
Omair Shamshir

Reputation: 2136

google app engine Efficient way to put large data in datastore

I want to store data in a parent child hierarchy. I want to do so using the ndb.put_multi function. The problem is how will i get the corresponding keys of the parents after i have stored parent models using put multi. Kindly suggest a solution

Upvotes: 1

Views: 362

Answers (2)

Brent Washburne
Brent Washburne

Reputation: 13138

The trick is to store a "grandparent" or root entity, and have all parent entities reference it in their key:

root = BaseClass()
root.put()
parent = Parent(parent=root)
parent.put()
child = Child(parent=parent)
child.put()

Now you can examine the child's key using the Instance methods:

parent = child.key.parent()
ancestors = child.key.pairs()

The reason you want a root entity is for Ancestor queries:

parents = Parent.query(ancestor=root)
children = Child.query(ancestor=root)

You can then examine the child.key.parent() to see its parent key.

Upvotes: 0

Jimmy Kane
Jimmy Kane

Reputation: 16825

If you have already used put_multi for the parent keys then you already have them.

Eg

list_of_parent_keys = ndb.put_multi(list_of_entities)
child_keys = []
for parent_key in list_of_parent_keys:
  child_key = ndb.Key(Parent, parent_key, Child, child_key)
  child_keys.append(child_key)

Upvotes: 4

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