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Cached one-to-many collections
Extend ReferenceProperty so the collection would not be fetched every time you iterate though it. So instead of returning a query the back reference modelname_set property will return the whole collection from memory.
Please notice that in the returned collection the hidden attribute __RESOLVED_master is already set to the same instance of Master, so you can go back and forth like this effectively:
Similar code would fetch both Master and Detail again and again with original ReferenceProperty.
class Master(db.Model):
pass
class Detail(db.Model):
master=CachedReferenceProperty(Master)
m=Master()
m.save()
d=Detail(master=m)
d.save()
m.detail_set #fetches and returns [d]
m.detail_set #returns cached value, no DataStore access
delete m.detail_set #resets the cached value
m.detail_set #value fetched again
m.detail_set[0].master.detail_set[-1].master
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