[Developers] Reverse sort with non-null values last or only non-null values

[Jack Alves]

I built a query to find all properties with expected_type=datetime. I want
to reverse sort by the instance_count of the type that contains the property
but I want null values to appear at the end of the results. 

Initially I tried the query below and discovered null values are returned
first.

{
  "query":[{
    "properties":[{
      "expected_type":"/type/datetime",
      "name":null,
      "schema":{
        "/freebase/type_profile/instance_count":null,
        "name":null
      }
    }],
    "sort":"-properties.schema./freebase/type_profile/instance_count",
    "type":"/type/type"
  }]
}


Then I figured out how to reverse sort the non-null results (thanks to
previous email thread Ketan/Dae).

{
  "query":[{
    "properties":[{
      "expected_type":"/type/datetime",
      "name":null,
      "schema":{
        "/freebase/type_profile/instance_count":{
          "value":null
        },
        "name":null
      }
    }],
    "sort":"-properties.schema./freebase/type_profile/instance_count.value",
    "type":"/type/type"
  }]
}

How do query for only null values? Is there a better way to do this? Do I
need to parse the results in my script?