Creating a Composite Index for AppEngine in Android-Studio-based project

Question

I used Android Studio to create both an Android project, and its backend AppEngine Endpoints counterpart. I have a datastore for which I am using Objectify. The system worked great, until I added a filter to my Query (to show only specific given emails).

Query<Report> query = ofy().load().type(Report.class).filter("email", user.getEmail()).order("email").order("-when").limit(limit);

This is the POJO Datastore Entity:

@Entity
public class Report {
    @Id
    Long id;

    String who;

    @Index
    Date when;

    String what;

    @Index
    String email;
}

However, I receive such an error from the Google API Explorer when I attempt to test it:

com.google.appengine.api.datastore.DatastoreNeedIndexException: no matching index found.
The suggested index for this query is:
    <datastore-index kind=\"AccessReport\" ancestor=\"false\" source=\"manual\">
    <property name=\"email\" direction=\"asc\"/>
    <property name=\"when\" direction=\"desc\"/>
    </datastore-index>

As I understand it, I simply need to create a composite index including the specific fields email and when, with their specific sort direction.

However, most documentation that I find tell me to edit datastore-indexes.xml.

App Engine predefines a simple index on each property of an entity. An App Engine application can define further custom indexes in an index configuration file named datastore-indexes.xml, which is generated in your application's /war/WEB-INF/appengine-generated directory.

Unfortunately, this file does not seem to exist anywhere in my project.

Is anyone familiar with the way to change this when working with Android Studio?

Andrei Volgin Andrei Volgin · Accepted Answer · 2015-12-19T21:27:18

Create datastore-indexes.xml file and put it in /WEB-INF/ folder. The content will look like this:

<datastore-indexes
  autoGenerate="true">

    <datastore-index kind=\"AccessReport\" ancestor=\"false\" source=\"manual\">
        <property name=\"email\" direction=\"asc\"/>
        <property name=\"when\" direction=\"desc\"/>
    </datastore-index>
</datastore-indexes>

Creating a Composite Index for AppEngine in Android-Studio-based project

1 Answers