Create Files.requires_python column (#1448)

Denormalize Release.requires_python into File.requires_python to better enable
performant retrieval of that information when fetching a list of files.

tests/unit/packaging/test_models.py

@@ -233,6 +233,20 @@ def test_urls(self, db_session, home_page, download_url, project_urls,
 
 class TestFile:
 
+    def test_requires_python(self, db_session):
+        """ Attempt to write a File by setting requires_python directly,
+            which should fail to validate (it should only be set in Release).
+        """
+        with pytest.raises(RuntimeError):
+            project = DBProjectFactory.create()
+            release = DBReleaseFactory.create(project=project)
+            DBFileFactory.create(
+                release=release,
+                filename="{}-{}.tar.gz".format(project.name, release.version),
+                python_version="source",
+                requires_python="1.0"
+            )
+
     def test_compute_paths(self, db_session):
         project = DBProjectFactory.create()
         release = DBReleaseFactory.create(project=project)

warehouse/migrations/versions/be4cf6b58557_add_requires_python_to_release_files.py

@@ -0,0 +1,88 @@
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""
+Add a requires_python column to release_files; pursuant to enabling PEP 503.
+
+Revision ID: be4cf6b58557
+Revises: 3d2b8a42219a
+Create Date: 2016-09-15 04:12:53.430363
+"""
+
+from alembic import op
+import sqlalchemy as sa
+
+
+revision = 'be4cf6b58557'
+down_revision = '3d2b8a42219a'
+
+
+def upgrade():
+    """
+    Add column `requires_python` in the `release_files` table.
+    """
+    op.add_column("release_files",
+                  sa.Column("requires_python",
+                            sa.Text(),
+                            nullable=True)
+                  )
+
+    # Populate the column with content from release.requires_python.
+    op.execute(
+        """ UPDATE release_files
+            SET requires_python = releases.requires_python
+            FROM releases
+            WHERE
+                release_files.name=releases.name
+                AND release_files.version=releases.version;
+        """
+    )
+
+    # Setup a trigger function to ensure that requires_python value on
+    # releases is always canonical.
+    op.execute(
+        """CREATE OR REPLACE FUNCTION update_release_files_requires_python()
+            RETURNS TRIGGER AS $$
+            BEGIN
+                UPDATE
+                    release_files
+                SET
+                    requires_python = releases.requires_python
+                FROM releases
+                WHERE
+                    release_files.name=releases.name
+                    AND release_files.version=releases.version
+                    AND release_files.name = NEW.name
+                    AND releases.version = NEW.version;
+                RETURN NULL;
+            END;
+            $$ LANGUAGE plpgsql;
+        """
+    )
+
+    # Establish a trigger such that on INSERT/UPDATE on releases we update
+    # release_files with the appropriate requires_python values.
+    op.execute(
+        """ CREATE TRIGGER releases_requires_python
+            AFTER INSERT OR UPDATE OF requires_python ON releases
+            FOR EACH ROW
+                EXECUTE PROCEDURE update_release_files_requires_python();
+        """
+    )
+
+
+def downgrade():
+    """
+    Drop trigger and function that synchronize `releases`.
+    """
+    op.execute("DROP TRIGGER releases_requires_python ON releases")
+    op.execute("DROP FUNCTION update_release_files_requires_python()")
+    op.drop_column("release_files", "requires_python")

warehouse/packaging/models.py

@@ -22,6 +22,7 @@
     Boolean, DateTime, Integer, Table, Text,
 )
 from sqlalchemy import func, orm, sql
+from sqlalchemy.orm import validates
 from sqlalchemy.orm.exc import NoResultFound
 from sqlalchemy.ext.associationproxy import association_proxy
 from sqlalchemy.ext.declarative import declared_attr
@@ -369,6 +370,7 @@ class File(db.Model):
     name = Column(Text)
     version = Column(Text)
     python_version = Column(Text)
+    requires_python = Column(Text)
     packagetype = Column(
         Enum(
             "bdist_dmg", "bdist_dumb", "bdist_egg", "bdist_msi", "bdist_rpm",
@@ -394,6 +396,10 @@ def pgp_path(self):
     def pgp_path(self):
         return func.concat(self.path, ".asc")
 
+    @validates("requires_python")
+    def validates_requires_python(self, *args, **kwargs):
+        raise RuntimeError("Cannot set File.requires_python")
+
 
 class Filename(db.ModelBase):