Bigtable: update helloworld example (#1670)

* Update helloworld example

* Use iterable PartialRowsData

bigtable/hello/main.py

@@ -25,8 +25,11 @@
 """
 
 import argparse
+import datetime
 
 from google.cloud import bigtable
+from google.cloud.bigtable import column_family
+from google.cloud.bigtable import row_filters
 
 
 def main(project_id, instance_id, table_id):
@@ -38,23 +41,25 @@ def main(project_id, instance_id, table_id):
     # [END connecting_to_bigtable]
 
     # [START creating_a_table]
-    print('Creating the {} table.'.format(table_id))
+    print 'Creating the {} table.'.format(table_id)
     table = instance.table(table_id)
-    table.create()
+    print 'Creating column family cf1 with Max Version GC rule...'
+    # Create a column family with GC policy : most recent N versions
+    # Define the GC policy to retain only the most recent 2 versions
+    max_versions_rule = column_family.MaxVersionsGCRule(2)
     column_family_id = 'cf1'
-    cf1 = table.column_family(column_family_id)
-    cf1.create()
+    column_families = {column_family_id: max_versions_rule}
+    if not table.exists():
+        table.create(column_families=column_families)
+    else:
+        print "Table {} already exists.".format(table_id)
     # [END creating_a_table]
 
     # [START writing_rows]
-    print('Writing some greetings to the table.')
-    column_id = 'greeting'.encode('utf-8')
-    greetings = [
-        'Hello World!',
-        'Hello Cloud Bigtable!',
-        'Hello Python!',
-    ]
-
+    print 'Writing some greetings to the table.'
+    greetings = ['Hello World!', 'Hello Cloud Bigtable!', 'Hello Python!']
+    rows = []
+    column = 'greeting'
     for i, value in enumerate(greetings):
         # Note: This example uses sequential numeric IDs for simplicity,
         # but this can result in poor performance in a production
@@ -68,35 +73,35 @@ def main(project_id, instance_id, table_id):
         #     https://cloud.google.com/bigtable/docs/schema-design
         row_key = 'greeting{}'.format(i)
         row = table.row(row_key)
-        row.set_cell(
-            column_family_id,
-            column_id,
-            value.encode('utf-8'))
-        row.commit()
+        row.set_cell(column_family_id,
+                     column,
+                     value,
+                     timestamp=datetime.datetime.utcnow())
+        rows.append(row)
+    table.mutate_rows(rows)
     # [END writing_rows]
 
     # [START getting_a_row]
-    print('Getting a single greeting by row key.')
+    print 'Getting a single greeting by row key.'
     key = 'greeting0'
-    row = table.read_row(key.encode('utf-8'))
-    value = row.cells[column_family_id][column_id][0].value
-    print('\t{}: {}'.format(key, value.decode('utf-8')))
+
+    # Only retrieve the most recent version of the cell.
+    row_filter = row_filters.CellsColumnLimitFilter(1)
+    row = table.read_row(key, row_filter)
+    print row.cell_value(column_family_id, column)
     # [END getting_a_row]
 
     # [START scanning_all_rows]
-    print('Scanning for all greetings:')
-    partial_rows = table.read_rows()
-    partial_rows.consume_all()
-
-    for row_key, row in partial_rows.rows.items():
-        key = row_key.decode('utf-8')
-        cell = row.cells[column_family_id][column_id][0]
-        value = cell.value.decode('utf-8')
-        print('\t{}: {}'.format(key, value))
+    print 'Scanning for all greetings:'
+    partial_rows = table.read_rows(filter_=row_filter)
+
+    for row in partial_rows:
+        cell = row.cells[column_family_id][column][0]
+        print cell.value.decode('utf-8')
     # [END scanning_all_rows]
 
     # [START deleting_a_table]
-    print('Deleting the {} table.'.format(table_id))
+    print 'Deleting the {} table.'.format(table_id)
     table.delete()
     # [END deleting_a_table]
 

bigtable/hello/requirements.txt

@@ -1,2 +1,2 @@
-google-cloud-bigtable==0.29.0
+google-cloud-bigtable==0.30.0
 google-cloud-core==0.28.1