Added Documentation Strings

Signed-off-by: Jason Myers <[email protected]>

Author: jasonamyers

redshift_sqlalchemy/dialect.py

@@ -57,17 +57,33 @@ def _get_column_info(self, name, format_type, default,
 
 
 class UnloadFromSelect(Executable, ClauseElement):
+    ''' Prepares a RedShift unload statement to drop a query to Amazon S3
+    http://docs.aws.amazon.com/redshift/latest/dg/r_UNLOAD_command_examples.html
+    '''
     def __init__(self, select, bucket, access_key, secret_key):
+        ''' Initializes an UnloadFromSelect instance
+
+        Args:
+            self: An instance of UnloadFromSelect
+            select: The select statement to be unloaded
+            bucket: The Amazon S3 bucket where the result will be stored
+            access_key: The Amazon Access Key ID
+            secret_key: The Amazon Secret Access Key
+        '''
         self.select = select
         self.bucket = bucket
         self.access_key = access_key
         self.secret_key = secret_key
 
 @compiles(UnloadFromSelect)
 def visit_unload_from_select(element, compiler, **kw):
+    ''' Returns the actual sql query for the UnloadFromSelect class
+    '''
     return "unload ('%(query)s') to '%(bucket)s' credentials 'aws_access_key_id=%(access_key)s;aws_secret_access_key=%(secret_key)s'" % {
         'query': element.select,
         'bucket': element.bucket,
         'access_key': element.access_key,
         'secret_key': element.secret_key,
     }
+
+

tests/test_unload_from_select.py

@@ -7,12 +7,16 @@
 
 class TestUnloadFromSelect(TestCase):
     def setUp(self):
+        ''' Sets up a in memory sqlite instance with a table
+        '''
         self.metadata = MetaData()
         self.t1 = Table('t1', self.metadata, Column('id', Integer, primary_key=True), Column('name', String))
         self.engine = create_engine('sqlite:///:memory:', echo=True)
         self.metadata.create_all(self.engine)
 
     def test_basic_unload_case(self):
+        ''' Tests that the simplest type of UnloadFromSelect works
+        '''
         expected_result = "unload ('SELECT count(t1.id) AS count_1 \nFROM t1') to 'cookies' credentials 'aws_access_key_id=cookies;aws_secret_access_key=cookies'"
         insert = UnloadFromSelect(select([func.count(self.t1.c.id)]), 'cookies', 'cookies', 'cookies')
         self.assertEqual(expected_result, str(insert))