do not eagerly convert expected values

- apply weak-equals comparison if necessary AFTER values have been
fetched from db

library/mysql_query.py

@@ -88,6 +88,35 @@
 ERR_NO_SUCH_TABLE = 4
 
 
+def weak_equals(a, b):
+    """
+    helper function to compare two values where one might be a string
+    :param a:
+    :param b:
+    :return:
+    """
+    # the simple case: a and b are of the same type, or of types that can be compared for equality (e.g.: int and float)
+    if type(a) == type(b) or a == b:
+        return a == b
+
+    # try to stringify both and compare then…
+    return str(a) == str(b)
+
+
+def tuples_weak_equals(a, b):
+    """
+    tests two tuples for weak equality
+    :param a:
+    :param b:
+    :return:
+    """
+    if len(a) == len(b):
+        pairs = zip(a, b)
+        return all([weak_equals(a, b) for a, b in pairs])
+
+    return False
+
+
 def change_required(cursor, table, identifiers, desired_values):
     """
     check if a change is required
@@ -122,7 +151,9 @@ def change_required(cursor, table, identifiers, desired_values):
     # bring the values argument into shape to compare directly to fetchone() result
     expected_query_result = tuple(desired_values.values())
     actual_result = cursor.fetchone()
-    if expected_query_result == actual_result:
+
+    # compare expected_query_result to actual_result with implicit casting
+    if tuples_weak_equals(expected_query_result, actual_result):
         return NO_ACTION_REQUIRED
 
     # a record has been found but does not match the desired values
@@ -216,18 +247,9 @@ def extract_column_value_maps(parameter):
     :param parameter:
     :return:
     """
-
-    def cast_if_necessary(v):
-        if isinstance(v, int):
-            return long(v)
-        if isinstance(v, str) and v.isdigit():
-            return long(v)
-
-        return v
-
     if parameter:
         for column, value in parameter.items():
-            yield (mysql_quote_identifier(column, 'column'), cast_if_necessary(value))
+            yield (mysql_quote_identifier(column, 'column'), value)
 
 
 def failed(action):

tests/test_mysql_query_multi_check.py

@@ -55,6 +55,28 @@ def test_no_change_required(self):
             values={'value1': '8', 'value2': 'admin', 'value3': "made up"},
         )
 
+        with self.assertRaises(AnsibleExitJson) as e:
+            self.module.main()
+
+        result = e.exception.args[0]
+
+        self.assertIn('changed', result)
+        self.assertFalse(result['changed'], 'no changed required is detected')
+        self.assertEquals(self.f.count_multicolumn_example(), 1, 'no additional row has been inserted in check-mode')
+
+    def test_change_detection_for_digits_in_strings(self):
+        # insert a row that does not need to be updated
+        self.f.insert_into_multicolumn_example(['elmar@athmer.org', 4, '5'], [8, '15', '16'])
+
+        set_module_args(
+            login_user=MYSQL_CONNECTION_PARAMS['user'],
+            name=MYSQL_CONNECTION_PARAMS['db'],
+            login_password=MYSQL_CONNECTION_PARAMS['passwd'],
+            login_host=MYSQL_CONNECTION_PARAMS['host'],
+            table='multicolumn_example',
+            identifiers=dict(identifier1='elmar@athmer.org', identifier2='4', identifier3='5'),
+            values={'value1': '8', 'value2': '15', 'value3': "16"},
+        )
 
         with self.assertRaises(AnsibleExitJson) as e:
             self.module.main()

tests/test_weak_equals.py

@@ -0,0 +1,34 @@
+import unittest
+
+from library.mysql_query import weak_equals
+
+
+class WeakEquals(unittest.TestCase):
+
+    def test_int_int(self):
+        self.assertTrue(weak_equals(42, 42))
+        self.assertFalse(weak_equals(42, 43))
+
+    def test_string_string(self):
+        self.assertTrue(weak_equals("a", "a"))
+        self.assertFalse(weak_equals("a", "b"))
+
+    def test_string_int(self):
+        self.assertTrue(weak_equals("1", 1))
+        self.assertTrue(weak_equals(1, "1"))
+        self.assertFalse(weak_equals("2", 1))
+        self.assertFalse(weak_equals(1, "2"))
+
+    def test_string_long(self):
+        self.assertTrue(weak_equals("1", 1L))
+        self.assertTrue(weak_equals(1L, "1"))
+        self.assertFalse(weak_equals("2", 1L))
+        self.assertFalse(weak_equals(1L, "2"))
+
+    def test_string_float(self):
+        self.assertTrue(weak_equals("1.1", 1.1))
+        self.assertTrue(weak_equals(1.1, "1.1"))
+        self.assertFalse(weak_equals("2", 1.1))
+        self.assertFalse(weak_equals(1.1, "2"))
+
+