- Added a fix to Postgresql server default comparison which first checks

if the text of the default is identical to the original, before attempting
to actually run the default.  This accomodates for default-generation
functions that generate a new value each time such as a uuid function.
fixes #365
- test against uuid_generate_v4() directly, but this requires extensions
to be installed.  should come up with a built in function for this test

diff --git a/alembic/ddl/postgresql.py b/alembic/ddl/postgresql.py
index 057ae4200c03b07456b561491336d6aa737d96b2..dd76639f8c1f29f6cc57c37053d91827182dac33 100644 (file)
--- a/alembic/ddl/postgresql.py
+++ b/alembic/ddl/postgresql.py
@@ -37,8 +37,12 @@ class PostgresqlImpl(DefaultImpl):
 
         conn_col_default = rendered_inspector_default
 
+        defaults_equal = conn_col_default == rendered_metadata_default
+        if defaults_equal:
+            return False
+
         if None in (conn_col_default, rendered_metadata_default):
-            return conn_col_default != rendered_metadata_default
+            return not defaults_equal
 
         if metadata_column.server_default is not None and \
             isinstance(metadata_column.server_default.arg,

diff --git a/docs/build/changelog.rst b/docs/build/changelog.rst
index a4fea82700e93f857e50ef81ca650d958bc042b7..4ac5941458a6cd8669c8f150291591fe550010bc 100644 (file)
--- a/docs/build/changelog.rst
+++ b/docs/build/changelog.rst
@@ -6,6 +6,15 @@ Changelog
 .. changelog::
     :version: 0.8.6
 
+    .. change::
+      :tags: bug, postgresql
+      :tickets: 365
+
+      Added a fix to Postgresql server default comparison which first checks
+      if the text of the default is identical to the original, before attempting
+      to actually run the default.  This accomodates for default-generation
+      functions that generate a new value each time such as a uuid function.
+
     .. change::
       :tags: bug, batch
       :tickets: 361

diff --git a/tests/requirements.py b/tests/requirements.py
index dd0de63c30838653515532c74ba40c83de829048..70db3e63dc00b957fd825f44e2997bb94388b385 100644 (file)
--- a/tests/requirements.py
+++ b/tests/requirements.py
@@ -78,3 +78,16 @@ class DefaultRequirements(SuiteRequirements):
 
         return exclusions.fails_on_everything_except(
             'postgresql', 'oracle', 'mssql', 'sybase')
+
+    @property
+    def postgresql_uuid_ossp(self):
+        def check_uuid_ossp(config):
+            if not exclusions.against(config, "postgresql"):
+                return False
+            try:
+                config.db.execute("SELECT uuid_generate_v4()")
+                return True
+            except:
+                return False
+
+        return exclusions.only_if(check_uuid_ossp)

diff --git a/tests/test_postgresql.py b/tests/test_postgresql.py
index 21ba6b9e7cb78e1b8cc370cc1fd0c916533907ae..b9973c28324bd68b2c098d116e59e6580a83abf0 100644 (file)
--- a/tests/test_postgresql.py
+++ b/tests/test_postgresql.py
@@ -1,7 +1,7 @@
 
 from sqlalchemy import DateTime, MetaData, Table, Column, text, Integer, \
     String, Interval, Sequence, Numeric, BigInteger, Float, Numeric
-from sqlalchemy.dialects.postgresql import ARRAY
+from sqlalchemy.dialects.postgresql import ARRAY, UUID
 from sqlalchemy.engine.reflection import Inspector
 from alembic.operations import Operations
 from sqlalchemy.sql import table, column
@@ -234,6 +234,13 @@ class PostgresqlDefaultCompareTest(TestBase):
             "14 days"
         )
 
+    @config.requirements.postgresql_uuid_ossp
+    def test_compare_uuid_text(self):
+        self._compare_default_roundtrip(
+            UUID,
+            text("uuid_generate_v4()")
+        )
+
     def test_compare_interval_text(self):
         self._compare_default_roundtrip(
             Interval,