Question

how do i query for a list of entities where a certain field of those entities is or (as shown in the datastore viewer).

Query query = pm.newQuery(DataObject.class, "this.SomeString == null");

The above code is not working for me, albeit there are entities in the datastore for which SomeString is either or when looking at the entities with the datastore viewer.

Answer 1

You can’t query for missing values. From Restrictions on Queries:

Entities lacking a property named in the query are ignored.

Entities of the same kind need not have the same properties. To be eligible as a query result, an entity must possess a value (possibly null) for every property named in the query’s filters and sort orders. If not, the entity is omitted from the indexes used to execute the query and consequently will not be included in the query’s results.

You can filter by null, however, so that part of your query should be working.