How to browse local Java App Engine datastore?

Question

It seems there is no equivalent of Python App Engine\'s _ah/admin for the Java implementation of Google App Engine.

Is there a manual way I can browse the datastore?

Answer 1

For me the fix was to do the login using below gcloud command

gcloud auth application-default login

Answer 2

Because Google App Engines Datastore viewer does not support displaying collections of referenced entities, I modified Paul's version to display all descendant entities:

public void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException {
    String entityParam = req.getParameter("e");

    resp.setContentType("text/plain");
    final DatastoreService datastore = DatastoreServiceFactory.getDatastoreService();

    // Original query
    final Query queryOrig = new Query(entityParam);
    queryOrig.addSort(Entity.KEY_RESERVED_PROPERTY, Query.SortDirection.ASCENDING);

    for (final Entity entityOrig : datastore.prepare(queryOrig).asIterable()) {

        // Query for this entity and all its descendant entities and collections
        final Query query = new Query();
        query.setAncestor(entityOrig.getKey());
        query.addSort(Entity.KEY_RESERVED_PROPERTY, Query.SortDirection.ASCENDING);

        for (final Entity entity : datastore.prepare(query).asIterable()) {
            resp.getWriter().println(entity.getKey().toString());

            // Print properties
            final Map<String, Object> properties = entity.getProperties();
            final String[] propertyNames = properties.keySet().toArray(new String[properties.size()]);
            for(final String propertyName : propertyNames) {
                resp.getWriter().println("-> " + propertyName + ": " + entity.getProperty(propertyName));
            }
        }
    }
}

It should be noted that nothing is displayed for empty collections/referenced entities.

Answer 3

I have local datastore on my Windows+Eclipse environment on \war\WEB-INF\appengine-generated\local_db.bin

As far as I understood it uses internal format named "protocol buffers". I don't have external tools to present the file in human-readable format.

I'm using simple "viewer" code like this:

public void doGet(HttpServletRequest req, HttpServletResponse resp) 
    throws IOException 
{

    resp.setContentType("text/plain");

    final DatastoreService datastore = DatastoreServiceFactory.getDatastoreService();
    final Query query = new Query("Table/Entity Name");
    //query.addSort(Entity.KEY_RESERVED_PROPERTY, Query.SortDirection.DESCENDING);

    for (final Entity entity : datastore.prepare(query).asIterable()) {
        resp.getWriter().println(entity.getKey().toString());

        final Map<String, Object> properties = entity.getProperties();
        final String[] propertyNames = properties.keySet().toArray(
            new String[properties.size()]);
        for(final String propertyName : propertyNames) {
            resp.getWriter().println("-> " + propertyName + ": " + entity.getProperty(propertyName));
        }
    }
}

Answer 4

Open the \war\WEB-INF\appengine-generated\local_db.bin file with a text editor, like Notepad++.

The data is scrambled but at least you can read it and you can copy to extract it.

Answer 5

In the newest versions of the SDK (1.7.6+) the admin part of the dev server comes with it changed its location

Analyzing the server output logs we can see that it is accessible at:

http://localhost:8000

And the Datastore viewer:

http://localhost:8000/datastore

Looks pretty neat - according to google's new design guidlines.

Answer 6

There's currently no datastore viewer for the Java SDK - one should be coming in the next SDK release. In the meantime, your best bet is to write your own admin interface with datastore viewing code - or wait for the next SDK release.

Java App Engine now has a local datastore viewer, accessible at http://localhost:8080/_ah/admin.