how to apply date filter on ancestor query

Question

I have two entity model Student and attendance such that each attendance entity has associated student parent.

Attendance model:

@Entity         


        

Answer 1

Answering Question 1:

Appengine uses UTC timestamps. Therefor your timestamp is converted from your time zone to UTC. It is still the same date and time though. During output you need to consider that the timestamp may contain the timezone and format / calculate the local time accordingly.

Answering Question 2:

You have all the information you need in your error. If you add

to your datastore-indexes.xml your query should work. If the file doesn't exist yet, create it under src/main/webapp/WEB-INF/datastore-indexes.xml, next to your web.xml and appengine-web.xml files. You can find an example on this page.

As for why: The answer with this error is always: Because datastore requires a composite index for this query.