Package com.google.cloud.datastore

Class Query<V>

java.lang.Object
com.google.cloud.datastore.Query<V>
Type Parameters:
V - the type of the values returned by this query.
All Implemented Interfaces:
Serializable
Direct Known Subclasses:
AggregationQuery, GqlQuery, StructuredQuery
public abstract class Query<V> extends Object implements Serializable
A Google Cloud Datastore query. For usage examples see GqlQuery, StructuredQuery and AggregationQuery.

Note that queries require proper indexing. See Cloud Datastore Index Configuration for help configuring indexes.

See Also:

  • Method Details

    • getNamespace

      public String getNamespace()

    • newGqlQueryBuilder

      public static GqlQuery.Builder<?> newGqlQueryBuilder(String gql)
      Returns a new GqlQuery builder.

      Example of creating and running a GQL query. 

      
 String kind = "my_kind";
 String gqlQuery = "select * from " + kind;
 Query<?> query = Query.newGqlQueryBuilder(gqlQuery).build();
 QueryResults<?> results = datastore.run(query);
 // Use results
      See Also:

    • newGqlQueryBuilder

      public static <V> GqlQuery.Builder<V> newGqlQueryBuilder(Query.ResultType<V> resultType, String gql)
      Returns a new GqlQuery builder.

      Example of creating and running a typed GQL query. 

      
 String kind = "my_kind";
 String gqlQuery = "select * from " + kind;
 Query<Entity> query = Query.newGqlQueryBuilder(Query.ResultType.ENTITY, gqlQuery).build();
 QueryResults<Entity> results = datastore.run(query);
 // Use results
      See Also:

    • newEntityQueryBuilder

      public static EntityQuery.Builder newEntityQueryBuilder()
      Returns a new StructuredQuery builder for full (complete entities) queries.

      Example of creating and running an entity query. 

      
 String kind = "my_kind";
 Query<Entity> query = Query.newEntityQueryBuilder().setKind(kind).build();
 QueryResults<Entity> results = datastore.run(query);
 // Use results

    • newKeyQueryBuilder

      public static KeyQuery.Builder newKeyQueryBuilder()
      Returns a new StructuredQuery builder for key only queries.

      Example of creating and running a key query. 

      
 String kind = "my_kind";
 Query<Key> query = Query.newKeyQueryBuilder().setKind(kind).build();
 QueryResults<Key> results = datastore.run(query);
 // Use results

    • newProjectionEntityQueryBuilder

      public static ProjectionEntityQuery.Builder newProjectionEntityQueryBuilder()
      Returns a new StructuredQuery builder for projection queries.

      Example of creating and running a projection entity query. 

      
 String kind = "my_kind";
 String property = "my_property";
 Query<ProjectionEntity> query = Query.newProjectionEntityQueryBuilder()
     .setKind(kind)
     .addProjection(property)
     .build();
 QueryResults<ProjectionEntity> results = datastore.run(query);
 // Use results

    • newAggregationQueryBuilder

      public static AggregationQuery.Builder newAggregationQueryBuilder()
      Returns a new AggregationQuery builder.

      Example of creating and running an AggregationQuery.

      StructuredQuery example: 

      
 EntityQuery selectAllQuery = Query.newEntityQueryBuilder()
    .setKind("Task")
    .build();
 AggregationQuery aggregationQuery = Query.newAggregationQueryBuilder()
    .addAggregation(count().as("total_count"))
    .over(selectAllQuery)
    .build();
 AggregationResults aggregationResults = datastore.runAggregation(aggregationQuery);
 // Use aggregationResults

      GqlQuery example: 

      
 GqlQuery<?> selectAllGqlQuery = Query.newGqlQueryBuilder(
         "AGGREGATE COUNT(*) AS total_count OVER(SELECT * FROM Task)"
     )
     .setAllowLiteral(true)
     .build();
 AggregationQuery aggregationQuery = Query.newAggregationQueryBuilder()
     .over(selectAllGqlQuery)
     .build();
 AggregationResults aggregationResults = datastore.runAggregation(aggregationQuery);
 // Use aggregationResults