def function_call_from_mapping(cursor, mapping_id):
function_mapping = FunctionMapping.load(mapping_id)(cursor)
arg_columns = ",".join(function_mapping.signature_columns)
if function_mapping.name is None:
if len(function_mapping.signature_columns) > 1:
raise Exception("cannot specify multiple columns in signature without a transforming function")
return Column(function_mapping.signature_columns[0])
else:
# deal with native (e.g. SUM, MAX) and custom transform functions
if is_custom_function(cursor, SCHEMA, function_mapping.name):
function = Function(SCHEMA, function_mapping.name)
else:
function = Function(function_mapping.name)
def signature_column_to_arg(c):
try:
int_val = int(c)
except ValueError:
return Column(c)
else:
return Value(int_val)
args = map(signature_column_to_arg, function_mapping.signature_columns)
return function.call(*args)
def test_function():
dummy_function = Function("add_many")
col_a = Column("counter_a")
col_b = Column("counter_b")
call = dummy_function.call(col_a, col_b)
eq_(call.render(), "add_many(counter_a, counter_b)")