CODEWITHSUNDEEP
pythongoogle-app-enginegoogle-cloud-datastore
Min Min
Min Min

Reputation: 135

Google DataStore - how to fetch data by date

I'm trying to write a fetch query for DataStore.

In datastore it has date field column with this format 2018-02-20 (11:07:36.000) MMT

I want to fetch only data of the specified date

I'm doing the following but it's not working:

def query(self, date=None):

    query = self.client.query(kind='Test')
    if date != None:
        query.add_filter('date', '>', datetime.strptime(date, '%Y%m%d').strftime('%Y-%m-%d'))
        query.add_filter('date', '<', datetime.strptime(date, '%Y%m%d').strftime('%Y-%m-%d'))

    results = list(query.fetch())
    print(results)

    return results


if __name__ == '__main__':
    date = 20181012
    data_list = query(date)

What am I doing wrong?

Upvotes: 1

Views: 3512

Answers (2)

Pratap Singh
Pratap Singh

Reputation: 429

Here is one way of doing a Date equality filtering via JDO Queries in GAE with JAVA Runtime:

public List<User> findByOrganizationIdAndDOB(Long organizationID, Date dateOfBirth) {
    PersistenceManager pm = PMF.get().getPersistenceManager();
    List<User> userList = null;
    try {

        Query q = pm.newQuery(User.class);
                q.declareImports("import java.util.Date");
                q.setFilter("organizationId ==organizationID && dateOfBirth==dateOfBirthParam");
                q.declareParameters("Long organizationID, Date dateOfBirthParam");
            
                userList = (List<User>) q.execute(organizationID,dateOfBirth);      
        
        return userList;
    } catch (Exception e) {
        e.printStackTrace();
        return null;
    } finally {
        pm.close();
    }

}

Upvotes: 0

Dan Cornilescu
Dan Cornilescu

Reputation: 39834

Side note: your date is an integer, passing it to datetime.strptime(date, '%Y%m%d') won't work, you'll get a TypeError: strptime() argument 1 must be string, not int. You'd need to use a string, not an int. But that's not really the problem.

In datastore it has date field column with this format 2018-02-20 (11:07:36.000) MMT

The format is irrelevant, you shouldn't operate with timestamp properties as strings. In other words you shouldn't needs to use strftime/strptime. You should deal with them as datetime objects instead. You can find an example in Restrictions on queries:

start_date = datetime.datetime(1990, 1, 1)
end_date = datetime.datetime(2000, 1, 1)
query = client.query(kind='Task')
query.add_filter(
    'created', '>', start_date)
query.add_filter(
    'created', '<', end_date)

Another important note is that your query with the filters added will never produce any result: no 'date' property value can simultaneously be both greater than and smaller than the same other value - your datetime.strptime(date, '%Y%m%d').strftime('%Y-%m-%d'), present in both filters. You need to provide 2 different start and end timestamp values in the 2 filters.

Adapting the above example for your question it'd be something like:

    query.add_filter('date', '>=', date)
    query.add_filter('date', '<', date + datetime.timedelta(days=1))

and you'd specify 'date' as a datetime:

date = datetime.datetime(2018, 10, 12)

Upvotes: 7

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