From: Mike Bayer <mike_mp@zzzcomputing.com>
Date: Wed, 20 Jan 2021 22:06:14 +0000 (-0500)
Subject: chain joins from SelectState context, not Select
X-Git-Tag: rel_1_4_0b2~36^2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b6ff056b91834ec56f685c8735cd67c9b0603de7;p=thirdparty%2Fsqlalchemy%2Fsqlalchemy.git

chain joins from SelectState context, not Select

Fixed issue in new :meth:`_sql.Select.join` method where chaining from the
current JOIN wasn't looking at the right state, causing an expression like
"FROM a JOIN b <onclause>, b JOIN c <onclause>" rather than
"FROM a JOIN b <onclause> JOIN c <onclause>".

Added :meth:`_sql.Select.outerjoin_from` method to complement
:meth:`_sql.Select.join_from`.

Fixes: #5858
Change-Id: I1346ebe0963bbd1e4bf868650e3ee1d6d3072f04
---

diff --git a/doc/build/changelog/unreleased_14/5858.rst b/doc/build/changelog/unreleased_14/5858.rst
new file mode 100644
index 0000000000..62cd4a751b
--- /dev/null
+++ b/doc/build/changelog/unreleased_14/5858.rst
@@ -0,0 +1,14 @@
+.. change::
+    :tags: bug, sql
+    :tickets: 5858
+
+    Fixed issue in new :meth:`_sql.Select.join` method where chaining from the
+    current JOIN wasn't looking at the right state, causing an expression like
+    "FROM a JOIN b <onclause>, b JOIN c <onclause>" rather than
+    "FROM a JOIN b <onclause> JOIN c <onclause>".
+
+.. change::
+    :tags: usecase, sql
+
+    Added :meth:`_sql.Select.outerjoin_from` method to complement
+    :meth:`_sql.Select.join_from`.
\ No newline at end of file
diff --git a/lib/sqlalchemy/sql/selectable.py b/lib/sqlalchemy/sql/selectable.py
index b4f6c8bc98..8e478583f6 100644
--- a/lib/sqlalchemy/sql/selectable.py
+++ b/lib/sqlalchemy/sql/selectable.py
@@ -3944,7 +3944,7 @@ class SelectState(util.MemoizedSlots, CompileState):
 
         replace_from_obj_index = None
 
-        from_clauses = self.statement._from_obj
+        from_clauses = self.from_clauses
 
         if from_clauses:
 
@@ -4644,6 +4644,19 @@ class Select(
             (target, onclause, None, {"isouter": isouter, "full": full}),
         )
 
+    def outerjoin_from(self, from_, target, onclause=None, full=False):
+        r"""Create a SQL LEFT OUTER JOIN against this :class:`_expression.Select`
+        object's criterion
+        and apply generatively, returning the newly resulting
+        :class:`_expression.Select`.
+
+        Usage is the same as that of :meth:`_selectable.Select.join_from`.
+
+        """
+        return self.join_from(
+            from_, target, onclause=onclause, isouter=True, full=full
+        )
+
     @_generative
     def join_from(
         self, from_, target, onclause=None, isouter=False, full=False
diff --git a/test/sql/test_select.py b/test/sql/test_select.py
index 2a2381427c..96c6abd073 100644
--- a/test/sql/test_select.py
+++ b/test/sql/test_select.py
@@ -41,6 +41,13 @@ child = Table(
     Column("data", String(50)),
 )
 
+grandchild = Table(
+    "grandchild",
+    metadata,
+    Column("id", Integer, primary_key=True),
+    Column("child_id", ForeignKey("child.id")),
+)
+
 
 class FutureSelectTest(fixtures.TestBase, AssertsCompiledSQL):
     __dialect__ = "default"
@@ -96,6 +103,20 @@ class FutureSelectTest(fixtures.TestBase, AssertsCompiledSQL):
             "ON mytable.myid = myothertable.otherid",
         )
 
+    def test_join_nofrom_implicit_left_side_explicit_onclause_3level(self):
+        stmt = (
+            select(parent)
+            .join(child, child.c.parent_id == parent.c.id)
+            .join(grandchild, grandchild.c.child_id == child.c.id)
+        )
+
+        self.assert_compile(
+            stmt,
+            "SELECT parent.id, parent.data FROM parent JOIN child "
+            "ON child.parent_id = parent.id "
+            "JOIN grandchild ON grandchild.child_id = child.id",
+        )
+
     def test_join_nofrom_explicit_left_side_explicit_onclause(self):
         stmt = select(table1).join_from(
             table1, table2, table1.c.myid == table2.c.otherid
@@ -108,6 +129,18 @@ class FutureSelectTest(fixtures.TestBase, AssertsCompiledSQL):
             "ON mytable.myid = myothertable.otherid",
         )
 
+    def test_outerjoin_nofrom_explicit_left_side_explicit_onclause(self):
+        stmt = select(table1).outerjoin_from(
+            table1, table2, table1.c.myid == table2.c.otherid
+        )
+
+        self.assert_compile(
+            stmt,
+            "SELECT mytable.myid, mytable.name, mytable.description "
+            "FROM mytable LEFT OUTER JOIN myothertable "
+            "ON mytable.myid = myothertable.otherid",
+        )
+
     def test_join_nofrom_implicit_left_side_implicit_onclause(self):
         stmt = select(parent).join(child)
 
@@ -117,6 +150,16 @@ class FutureSelectTest(fixtures.TestBase, AssertsCompiledSQL):
             "ON parent.id = child.parent_id",
         )
 
+    def test_join_nofrom_implicit_left_side_implicit_onclause_3level(self):
+        stmt = select(parent).join(child).join(grandchild)
+
+        self.assert_compile(
+            stmt,
+            "SELECT parent.id, parent.data FROM parent JOIN child "
+            "ON parent.id = child.parent_id "
+            "JOIN grandchild ON child.id = grandchild.child_id",
+        )
+
     def test_join_nofrom_explicit_left_side_implicit_onclause(self):
         stmt = select(parent).join_from(parent, child)
 
@@ -172,6 +215,19 @@ class FutureSelectTest(fixtures.TestBase, AssertsCompiledSQL):
             "ON parent.id = child.parent_id",
         )
 
+    def test_right_nested_inner_join(self):
+        inner = child.join(grandchild)
+
+        stmt = select(parent).outerjoin_from(parent, inner)
+
+        self.assert_compile(
+            stmt,
+            "SELECT parent.id, parent.data FROM parent "
+            "LEFT OUTER JOIN "
+            "(child JOIN grandchild ON child.id = grandchild.child_id) "
+            "ON parent.id = child.parent_id",
+        )
+
     def test_joins_w_filter_by(self):
         stmt = (
             select(parent)