Include DISTINCT in error message for label reference

Needed to add tests to ensure this label reference is handled
correctly, so also modified the exception message to
be more clear if someone has this error within distinct().

Change-Id: I6e685e46ae336596272d14366445ac224c18d92c

diff --git a/doc/build/changelog/unreleased_13/dist_warn.rst b/doc/build/changelog/unreleased_13/dist_warn.rst
new file mode 100644 (file)
index 0000000..b70a9f0
--- /dev/null
+++ b/doc/build/changelog/unreleased_13/dist_warn.rst
@@ -0,0 +1,7 @@
+.. change::
+    :tags: bug, sql
+
+    Changed the text of the exception for "Can't resolve label reference" to
+    include other kinds of label coercions, namely that "DISTINCT" is also in
+    this category under the PostgreSQL dialect.
+

diff --git a/lib/sqlalchemy/sql/compiler.py b/lib/sqlalchemy/sql/compiler.py
index 85c1750b7b0287288dc319ed6af6e67f51a3c57c..a28ce465a911e905902a04e25b45bdb8544f3aeb 100644 (file)
--- a/lib/sqlalchemy/sql/compiler.py
+++ b/lib/sqlalchemy/sql/compiler.py
@@ -811,7 +811,10 @@ class SQLCompiler(Compiled):
         except KeyError:
             coercions._no_text_coercion(
                 element.element,
-                extra="Can't resolve label reference for ORDER BY / GROUP BY.",
+                extra=(
+                    "Can't resolve label reference for ORDER BY / "
+                    "GROUP BY / DISTINCT etc."
+                ),
                 exc_cls=exc.CompileError,
             )
         else:

diff --git a/test/orm/test_query.py b/test/orm/test_query.py
index 2bc0af3c26f8b1977c7a1ba369331c6cd1787957..068a7c8937821dcc83b1fe1d35d305c05b3f1dfd 100644 (file)
--- a/test/orm/test_query.py
+++ b/test/orm/test_query.py
@@ -3990,6 +3990,45 @@ class DistinctTest(QueryTest, AssertsCompiledSQL):
             dialect="postgresql",
         )
 
+    def test_columns_augmented_sql_three_using_label_reference(self):
+        User, Address = self.classes.User, self.classes.Address
+
+        sess = create_session()
+
+        q = (
+            sess.query(User.id, User.name.label("foo"), Address.id)
+            .distinct("name")
+            .order_by(User.id, User.name, Address.email_address)
+        )
+
+        # no columns are added when DISTINCT ON is used
+        self.assert_compile(
+            q,
+            "SELECT DISTINCT ON (users.name) users.id AS users_id, "
+            "users.name AS foo, addresses.id AS addresses_id FROM users, "
+            "addresses ORDER BY users.id, users.name, addresses.email_address",
+            dialect="postgresql",
+        )
+
+    def test_columns_augmented_sql_illegal_label_reference(self):
+        User, Address = self.classes.User, self.classes.Address
+
+        sess = create_session()
+
+        q = sess.query(User.id, User.name.label("foo"), Address.id).distinct(
+            "not a label"
+        )
+
+        from sqlalchemy.dialects import postgresql
+
+        assert_raises_message(
+            sa_exc.CompileError,
+            "Can't resolve label reference for ORDER BY / "
+            "GROUP BY / DISTINCT etc.",
+            q.with_labels().statement.compile,
+            dialect=postgresql.dialect(),
+        )
+
     def test_columns_augmented_sql_four(self):
         User, Address = self.classes.User, self.classes.Address
 

diff --git a/test/sql/test_compiler.py b/test/sql/test_compiler.py
index ca73f6c18c1ada7d07d6715bb153f8eaa942f5c9..486b546828024ee0bc3077c1c8c70b70fc729c4f 100644 (file)
--- a/test/sql/test_compiler.py
+++ b/test/sql/test_compiler.py
@@ -2073,7 +2073,8 @@ class SelectTest(fixtures.TestBase, AssertsCompiledSQL):
         # to check the special thing CompoundSelect does with labels
         assert_raises_message(
             exc.CompileError,
-            "Can't resolve label reference for ORDER BY / GROUP BY. Textual "
+            "Can't resolve label reference for ORDER BY / GROUP BY / "
+            "DISTINCT etc. Textual "
             "SQL expression 'noname'",
             union(
                 select([table1.c.myid, table1.c.name]),

diff --git a/test/sql/test_text.py b/test/sql/test_text.py
index 3f12d06a90f3f13c9efbe910eddf2fd7157c5772..3386d0aae952610f5bbdd9b595196bb418c75174 100644 (file)
--- a/test/sql/test_text.py
+++ b/test/sql/test_text.py
@@ -678,14 +678,16 @@ class TextErrorsTest(fixtures.TestBase, AssertsCompiledSQL):
 class OrderByLabelResolutionTest(fixtures.TestBase, AssertsCompiledSQL):
     __dialect__ = "default"
 
-    def _test_exception(self, stmt, offending_clause):
+    def _test_exception(self, stmt, offending_clause, dialect=None):
         assert_raises_message(
             exc.CompileError,
-            r"Can't resolve label reference for ORDER BY / GROUP BY. "
+            r"Can't resolve label reference for ORDER BY / GROUP BY / "
+            "DISTINCT etc. "
             "Textual SQL "
             "expression %r should be explicitly "
             r"declared as text\(%r\)" % (offending_clause, offending_clause),
             stmt.compile,
+            dialect=dialect,
         )
 
     def test_order_by_label(self):
@@ -736,6 +738,21 @@ class OrderByLabelResolutionTest(fixtures.TestBase, AssertsCompiledSQL):
         stmt = select([table1.c.myid]).order_by("foobar")
         self._test_exception(stmt, "foobar")
 
+    def test_distinct_label(self):
+
+        stmt = select([table1.c.myid.label("foo")]).distinct("foo")
+        self.assert_compile(
+            stmt,
+            "SELECT DISTINCT ON (foo) mytable.myid AS foo FROM mytable",
+            dialect="postgresql",
+        )
+
+    def test_unresolvable_distinct_label(self):
+        from sqlalchemy.dialects import postgresql
+
+        stmt = select([table1.c.myid.label("foo")]).distinct("not a label")
+        self._test_exception(stmt, "not a label", dialect=postgresql.dialect())
+
     def test_group_by_label(self):
         stmt = select([table1.c.myid.label("foo")]).group_by("foo")
         self.assert_compile(
@@ -890,7 +907,8 @@ class OrderByLabelResolutionTest(fixtures.TestBase, AssertsCompiledSQL):
 
         assert_raises_message(
             exc.CompileError,
-            r"Can't resolve label reference for ORDER BY / GROUP BY. "
+            r"Can't resolve label reference for ORDER BY / GROUP BY / "
+            "DISTINCT etc. "
             "Textual SQL "
             "expression 't1name' should be explicitly "
             r"declared as text\('t1name'\)",