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Development Team/Almanac/sugar.datastore.datastore: Difference between revisions

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{{Sugar Almanac TOC}}
{{Almanac}}
{{Almanac TOC}}


= High Level Functionality of the Datastore =
= High Level Functionality of the Datastore =
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=== How do I provide a query to the datastore.find() method so that I can find datastore objects with a particular property? ===
=== How do I provide a query to the datastore.find() method so that I can find datastore objects with a particular property? ===
'''IMPORTANT''' Do not rely on datastore.find() method in all cases, its behaviour could be changed in future releases;<br>there is only on thing for sure: to treat jobjects that were created within activity use:<br>datastore.find({'activity_id': <activity-id-of(and only of)-current-activity>, ...})
The datastore package includes a find() helper function that allows you to find things in the datastore. Belows is a very simple example use of find where I simply search for journal entries that have a title of 'file1.txt'. I think print out the title and file path for each retreived entry.  
The datastore package includes a find() helper function that allows you to find things in the datastore. Belows is a very simple example use of find where I simply search for journal entries that have a title of 'file1.txt'. I think print out the title and file path for each retreived entry.  


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         print "Number of Objects: " + str(num_objects)
         print "Number of Objects: " + str(num_objects)


         for i in xrange (0, num_objects, 1):
         for i in xrange (num_objects):
             print "File Path: " + ds_objects[i].get_file_path()
             print "File Path: " + ds_objects[i].get_file_path()
             print "Title: " + ds_objects[i].metadata['title']
             print "Title: " + ds_objects[i].metadata['title']
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<pre>
<pre>
  datastore.find({'title':['this','that'],
  datastore.find({'title':['this','that'],
                 'activity':'org.laptop.ReadActivity',
                 'activity':'org.laptop.sugar.ReadActivity',
                 'mime_type':'application/pdf',
                 'mime_type':'application/pdf',
                 'mtime':{'start':datetime.today().replace(hour=0, minute=0, second=0),'end':datetime.today().replace(hour=23, minute=59, second=59)}})
                 'mtime':{'start':datetime.today().replace(hour=0, minute=0, second=0),
                          'end':datetime.today().replace(hour=23, minute=59, second=59)}})
</pre>
</pre>


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         #loop through and delete each datastore object found.  
         #loop through and delete each datastore object found.  
         for i in xrange (0, num_objects, 1):
         for i in xrange (num_objects):
             print 'DELETING ' + ds_objects[i].metadata['title'] + '...'
             print 'DELETING ' + ds_objects[i].metadata['title'] + '...'
             ds_objects[i].destroy()
             ds_objects[i].destroy()
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         #loop through list of values and print them out.  
         #loop through list of values and print them out.  
         for i in xrange(0, len(unique_val_array), 1):
         for x in unique_val_array:
             print str(unique_val_array[i])
             print x
</pre>
</pre>


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         print '------------------------MOUNTS--------------------------------'
         print '------------------------MOUNTS--------------------------------'
         ds_mounts = datastore.mounts()
         ds_mounts = datastore.mounts()
         for i in xrange(0, len(ds_mounts), 1):
         for x in ds_mounts:
             print '---------MOUNT---------'
             print '---------MOUNT---------'
             print 'title: '+ ds_mounts[i]['title']
             print 'title: '+ x['title']
             print 'uri: '+ ds_mounts[i]['uri']
             print 'uri: '+ x['uri']
             print 'id: ' + ds_mounts[i]['id']
             print 'id: ' + x['id']
          
          
</pre>
</pre>
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= Class: DSObject =
= Class: DSObject =
=== How do I access the metadata entries for a datastore object? ===
Every DSObject created by datastore.create() has a metadata property. This property refers to a [[Low-level_Activity_API#Meta_Data|DS Object]], which contains the metadata for your datastore object. The code below shows how to read metadata values by referring to the metadata property of a DSObject. metadata is a Python dictionary object.
<pre>
from sugar.datastore import datastore
...
        #my_dsobject is of type datastore.DSObject
        #object_id is a datastore object (e.g., returned from the datastore Chooser)
        my_dsobject = datastore.get(object_id)
       
        #Access the 'description' property
        print my_dsobject.metadata['description']
</pre>
This code snippet shows how to create a pixbuf from the preview entry in the datastore:
<pre>
from sugar.datastore import datastore
...
        #my_dsobject is of type datastore.DSObject
        #object_id is a datastore object
        my_dsobject = datastore.get(object_id)
        pixbufloader = gtk.gdk.pixbuf_loader_new_with_mime_type('image/png')
        #Access the 'preview' property
        #Note that the preview image is 300x225
        pixbufloader.write(dsobject.metadata['preview'])
        pixbufloader.close()
        pixbuf = pixbufloader.get_pixbuf()
</pre>


=== How do I create new metadata entries or reassign metadata for a datastore object that has been created? ===
=== How do I create new metadata entries or reassign metadata for a datastore object that has been created? ===
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