How do I only save date and not datetime in google datasource

Question

I'm working on an android app with gae as backend. I have two queries around DateTime object com.google.gdata.data.DateTime

While inserting data, I only want to to insert date and not datetime. Here's current object creation and it saves both date and time.
```
stock.setDate(new DateTime(new Date()));
```

Also while retrieving stock object, where I have aggregated data, I want to group by date and not datetime. But as the data got stored as date and time, I'm getting group by datetime, where as I want date. What to do in such scenarios (yes, if we solve 1st problem this wont be required, but otherwise what should be done). My retrieval code is

List<AggregatedStock> execute = null;

PersistenceManager pm = getPersistenceManager();
Query query = pm
        .newQuery(" select date, vehicleCode, vehicleSubCode, colorCode, sum(count) from Stock as AggregatedStock ");

query.setFilter(" updatedByDealer == " + dealer);
query.setGrouping(" date, vehicleCode, vehicleSubCode, colorCode ");
query.setOrdering(" vehicleCode desc ");

query.declareImports("import com.sandeepapplabs.dms.Stock");

try {
    List<Object[]> results = (List<Object[]>) query.execute();

    execute = new ArrayList<AggregatedStock>();

    for (Object[] result : results) {
        execute.add(new AggregatedStock((Date) result[0],
                (String) result[1], (String) result[2],
                (String) result[3], ((Long) result[4]).intValue()));
    }

} finally {
    pm.close();
}

return execute;

Some people downvote without thinking. Don't be upset. And welcome to the community! — Andrei Volgin, Dec 24 '14 at 17:41
And sometimes a question is down-voted when it's author could not be bothered to search for the hundreds of pre-existing duplicate Qiestions and Answers. — Basil Bourque, Dec 25 '14 at 18:32
@BasilBourque: In which case it is useful (and polite) to explain to a *new* member why a question was downvoted. — Andrei Volgin, Dec 26 '14 at 03:05

score 1 · Answer 1 · edited May 23 '17 at 10:33

A Date is a single moment in time. It's a not a "day" that lasts 24 hours. When you call new Date(), you get a different moment - down to a millisecond - each time. Note that there is no difference here between Date and DateTime - the DateTime is simply a Date with a chronology.

You have three options if you want to use the "date as a day" to group your entities:

(a) Always set the date as a midnight (how to create a Java Date object of midnight today and midnight tomorrow?).

(b) Save it as new Date(), but extract the "day" portion or convert it into a String formatted to represent a calendar day before using it to group entities.

(c) Store and use dates as String values (i.e. "2014-12-24").

score 0 · Answer 2 · answered Dec 23 '14 at 21:16

0

App Engine supports java.util.Date as a property. Complete list of supported value types can be found here

answered Dec 23 '14 at 21:16

Jose Montes de Oca

879
6
9

Yes it does, but when I generate cloud endpoint libraries, it creates model classes with Date as DateTime. Sample from generated model `@SuppressWarnings("javadoc") public final class Stock extends com.google.api.client.json.GenericJson { /** * The value may be {@code null}. */ @com.google.api.client.util.Key private com.google.api.client.util.DateTime date;` – Sandeep Choudhary Dec 24 '14 at 05:15
Any why a downvote?? I'm new to this so please let me know so that I improve things at my end – Sandeep Choudhary Dec 24 '14 at 05:17

How do I only save date and not datetime in google datasource

2 Answers2