CODEWITHSUNDEEP
google-app-enginegoogle-cloud-datastoreobjectifydatastore
VitalyT
VitalyT

Reputation: 1691

App engine Datastore : How make a query / filter that return entity count with specific array size?

I have an Entity with different properties, one of the propery is Array of Objects , I'm working with Java using Objectify

now I want to make a query with filter to return count of all entities only with specific array size , E.g messages size=2

Example:

Kind: Request

and propery : 

    name messeges 
        {
          "values": [
            {
              "K1": "V1",
              "K2": "V2"
            },
            {
              "K3": "V3",
              "K4": "V4"
            },
            {
              "K5": "V5",
              "K6": "V6"
            }
          ]
        }

Something like : 

int count = ofy().load().type(Request.class).filter("?? return count , to query with messages size is 2..").count()

Any suggestions plesae?

Upvotes: 1

Views: 462

Answers (1)

Dan Cornilescu
Dan Cornilescu

Reputation: 39824

There is no way to make such query with the datastore.

But you could add a property to your entity, let's call it values_count, to reflect the values array size and make an equality query on that property instead (e.g. values_count=2)

I'd make it a computed property, automatically updated whenever the entity is updated, see Is it possible to have a computed property on Google App Engine using Java?

Upvotes: 1

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