Question

What is the recommended (read most efficient) way to obtain a single entity out of the datastore based on a value that’s closest to one provided.

For example, I have the following DataModel:

class MyObject(db.Model):
    someValue = db.IntegerProperty()
    shortDescription = db.TextProperty()

During a GET a value is passed in, I would like to query the datastore for the object(s) that are the closest to the provided value.

Multiple results are fine if they are the same distance. I.e. if I have two objects with someValue at 2 and 4 and I pass in 3.

Any advice would be appreciated.

Answer 1

An ascending and descending index is automatically created for all properties, so you can do something like this:

results1 = MyObject.all().order('someValue').filter('someValue >=', 3).fetch(50)
results2 = MyObject.all().order('-someValue').filter('someValue <', 3).fetch(50)

This will give you two result sets with up to 100 objects in the proximity of your search value.