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
public class Attendance {

 @Id
 Long id;
 @Index
 Date date;
 @Parent
 @Index
 @ApiResourceProperty(ignored = AnnotationBoolean.TRUE)
 Ref<Student> studentRef;

 public Long getId() {
 return id;
 }

 public Date getDate() {
 return date;
 }

 public void setDate(Date date) {
 this.date = date;
 }
 public String getWebsafeKey() {
 return Key.create(studentRef.getKey(), Attendance.class, id).getString();
 }
}

Student model:

@Entity
public class Student {

 @Id
 Long id;
 @Index
 String name;

 String student_id;

 Long mobile_number;
 String email;

 @Index
 @ApiResourceProperty(ignored = AnnotationBoolean.TRUE)
 List<Ref<Shift>> shiftRef = new ArrayList<Ref<Shift>>();

 public Long getId() {
 return id;
 }

 public String getStudent_id() {
 return student_id;
 }

 public void setStudent_id(String student_id) {
 this.student_id = student_id;
 }

 public String getName() {
 return name;
 }

 public void setName(String name) {
 this.name = name;
 }

 public Long getMobile_number() {
 return mobile_number;
 }

 public void setMobile_number(Long mobile_number) {
 this.mobile_number = mobile_number;
 }

 public String getEmail() {
 return email;
 }

 public void setEmail(String email) {
 this.email = email;
 }

 public String getWebsafeKey() {
 return Key.create(Student.class, id).getString();
 }
}

This how I am inserting an attendance entity into datastore:

Key<Student> studentKey = Key.create(student_web_safe_key);
Date date = new Date();
date.setTime(System.currentTimeMillis());
attendance.setDate(date);
attendance.studentRef = Ref.create(studentKey);
ofy().save().entity(attendance).now();

Questions:

The above query store the date in datastore in format:2016-06-15 (18:01:18.845)IST
But when I retrieve the same entity without specifying its parent then its gives me date as: "date ": "2016-06-15T12:31:18.845Z". please explain this?
I am able to store attendance corresponds to each student and also able to retrieve all the attendance of a student. but how can retrieve attendance of student on specified date or range of dates? I tried blow query: Query query = ofy().load().type(Attendance.class).ancestor(studentKey).filter("date =",date);

but it gives me following exception:

com.google.api.client.googleapis.json.GoogleJsonResponseException: 

503 Service Unavailable
    {
      "code": 503,
      "errors": [
        {
          "domain": "global",
          "message": "com.google.appengine.api.datastore.DatastoreNeedIndexException: no matching index found. recommended index is:\n- kind: Attendance\n  ancestor: yes\n  properties:\n  - name: date\n\nThe suggested index for this query is:\n    <datastore-index kind=\"Attendance\" ancestor=\"true\" source=\"manual\">\n        <property name=\"date\" direction=\"asc\"/>\n    </datastore-index>\n\n",
          "reason": "backendError"
        }
      ],
      "message": "com.google.appengine.api.datastore.DatastoreNeedIndexException: no matching index found. recommended index is:\n- kind: Attendance\n  ancestor: yes\n  properties:\n  - name: date\n\nThe suggested index for this query is:\n    <datastore-index kind=\"Attendance\" ancestor=\"true\" source=\"manual\">\n        <property name=\"date\" direction=\"asc\"/>\n    </datastore-index>\n\n"
    }

Micro Micro · Accepted Answer · 2016-06-16T15:34:30

Just wanted to add to konqi's answer based on comments:

If you are using Cloud Endpoints with Android Studio you must first switch to "project" view in your navigation panel, then navigate to your "backend" folder then src->main->webapp->WEB-INF and then in that folder you must manually create a datastore-indexes.xml file. Here is what yours would look like:

<?xml version="1.0" encoding="utf-8"?>
<datastore-indexes autoGenerate="true">
    <!-- NOTE: Not necessary to create composite indexes here for single property indices b.c. they are build in.-->

    <!-- If you do not specify direction, default is: direction="asc" -->

    <datastore-index kind="Attendance" ancestor="true" source="manual">
        <property name="date" direction="asc"/>
    </datastore-index>

</datastore-indexes>

how to apply date filter on ancestor query

2 Answers