Merge "Accommodate for SQLAlchemy 1.4 deferral of index/unique names"

4 files changed, 92 insertions, 13 deletions

diff --git a/alembic/autogenerate/compare.py b/alembic/autogenerate/compare.py
index 49ceb21..cacedee 100644
--- a/alembic/autogenerate/compare.py
+++ b/alembic/autogenerate/compare.py
@@ -338,7 +338,9 @@ def _compare_columns(
 
 class _constraint_sig(object):
     def md_name_to_sql_name(self, context):
-        return self.name
+        return sqla_compat._get_constraint_final_name(
+            self.const, context.dialect
+        )
 
     def __eq__(self, other):
         return self.const == other.const
@@ -529,7 +531,8 @@ def _compare_indexes_and_uniques(
     metadata_names = dict(
         (c.md_name_to_sql_name(autogen_context), c)
         for c in metadata_unique_constraints.union(metadata_indexes)
-        if c.name is not None
+        if isinstance(c, _ix_constraint_sig)
+        or sqla_compat._constraint_is_named(c.const, autogen_context.dialect)
     )
 
     conn_uniques_by_name = dict((c.name, c) for c in conn_unique_constraints)
@@ -556,7 +559,11 @@ def _compare_indexes_and_uniques(
     )
     metadata_indexes_by_sig = dict((ix.sig, ix) for ix in metadata_indexes)
     unnamed_metadata_uniques = dict(
-        (uq.sig, uq) for uq in metadata_unique_constraints if uq.name is None
+        (uq.sig, uq)
+        for uq in metadata_unique_constraints
+        if not sqla_compat._constraint_is_named(
+            uq.const, autogen_context.dialect
+        )
     )
 
     # assumptions:
diff --git a/alembic/util/sqla_compat.py b/alembic/util/sqla_compat.py
index 3733142..c3b10dc 100644
--- a/alembic/util/sqla_compat.py
+++ b/alembic/util/sqla_compat.py
@@ -183,15 +183,11 @@ def _column_kwargs(col):
 
 
 def _get_index_final_name(dialect, idx):
-    # trying to keep the truncation rules totally localized on the
-    # SQLA side while also stepping around the quoting issue.   Ideally
-    # the _prepared_index_name() method on the SQLA side would have
-    # a quoting option or the truncation routine would be broken out.
-    #
-    # test for SQLA quoted_name construct, introduced in
-    # 0.9 or thereabouts.
-    # this doesn't work in 0.8 and the "quote" option on Index doesn't
-    # seem to work in 0.8 either.
+    if sqla_14:
+        return _get_constraint_final_name(idx, dialect)
+
+    # prior to SQLAlchemy 1.4, work around quoting logic to get at the
+    # final compiled name without quotes.
     if hasattr(idx.name, "quote"):
         # might be quoted_name, might be truncated_name, keep it the
         # same
@@ -201,6 +197,35 @@ def _get_index_final_name(dialect, idx):
     return dialect.ddl_compiler(dialect, None)._prepared_index_name(idx)
 
 
+def _get_constraint_final_name(constraint, dialect):
+    if sqla_14:
+        if constraint.name is None:
+            return None
+
+        # for SQLAlchemy 1.4 we would like to have the option to expand
+        # the use of "deferred" names for constraints as well as to have
+        # some flexibility with "None" name and similar; make use of new
+        # SQLAlchemy API to return what would be the final compiled form of
+        # the name for this dialect.
+        return dialect.identifier_preparer.format_constraint(
+            constraint, _alembic_quote=False
+        )
+    else:
+        return constraint.name
+
+
+def _constraint_is_named(constraint, dialect):
+    if sqla_14:
+        if constraint.name is None:
+            return False
+        name = dialect.identifier_preparer.format_constraint(
+            constraint, _alembic_quote=False
+        )
+        return name is not None
+    else:
+        return constraint.name is not None
+
+
 def _dialect_supports_comments(dialect):
     if sqla_120:
         return dialect.supports_comments
diff --git a/docs/build/unreleased/sqla14_4911.rst b/docs/build/unreleased/sqla14_4911.rst
new file mode 100644
index 0000000..71463cb
--- /dev/null
+++ b/docs/build/unreleased/sqla14_4911.rst
@@ -0,0 +1,7 @@
+.. change::
+    :tags: change, compatibility
+
+    Some internal modifications have been made to how the names of indexes and
+    unique constraints work to make use of new functions added in SQLAlchemy
+    1.4, so that SQLAlchemy has more flexibility over how naming conventions
+    may be applied to these objects.
diff --git a/tests/test_autogen_indexes.py b/tests/test_autogen_indexes.py
index c8eaffb..416444c 100644
--- a/tests/test_autogen_indexes.py
+++ b/tests/test_autogen_indexes.py
@@ -18,6 +18,7 @@ from alembic.testing import engines
 from alembic.testing import eq_
 from alembic.testing import TestBase
 from alembic.testing.env import staging_env
+from alembic.util import sqla_compat
 from ._autogen_fixtures import AutogenFixtureTest
 
 py3k = sys.version_info >= (3,)
@@ -204,7 +205,12 @@ class AutogenerateUniqueIndexTest(AutogenFixtureTest, TestBase):
         eq_(diffs[0][0], "add_table")
 
         eq_(diffs[1][0], "add_index")
-        eq_(diffs[1][1].name, "ix_extra_foo")
+        eq_(
+            sqla_compat._get_constraint_final_name(
+                diffs[1][1], config.db.dialect
+            ),
+            "ix_extra_foo",
+        )
 
         eq_(diffs[2][0], "add_index")
         eq_(diffs[2][1].name, "newtable_idx")
@@ -257,6 +263,40 @@ class AutogenerateUniqueIndexTest(AutogenFixtureTest, TestBase):
         diffs = self._fixture(m1, m2)
         eq_(diffs, [])
 
+    def test_nothing_changed_implicit_uq_w_naming_conv(self):
+        m1 = MetaData(
+            naming_convention={
+                "ix": "ix_%(column_0_label)s",
+                "uq": "uq_%(column_0_label)s",
+            }
+        )
+        m2 = MetaData(
+            naming_convention={
+                "ix": "ix_%(column_0_label)s",
+                "uq": "uq_%(column_0_label)s",
+            }
+        )
+
+        Table(
+            "nothing_changed",
+            m1,
+            Column("id1", Integer, primary_key=True),
+            Column("id2", Integer, primary_key=True),
+            Column("x", String(20), unique=True),
+            mysql_engine="InnoDB",
+        )
+
+        Table(
+            "nothing_changed",
+            m2,
+            Column("id1", Integer, primary_key=True),
+            Column("id2", Integer, primary_key=True),
+            Column("x", String(20), unique=True),
+            mysql_engine="InnoDB",
+        )
+        diffs = self._fixture(m1, m2)
+        eq_(diffs, [])
+
     def test_nothing_changed_two(self):
         m1 = MetaData()
         m2 = MetaData()