From 83f18928516637c0efc5d05631f51b5f0538e742 Mon Sep 17 00:00:00 2001
From: Giulia Naponiello <gnaponie@redhat.com>
Date: Feb 12 2018 17:05:26 +0000
Subject: Changes on schema migration for backward compatibility


In changing waiverdb to record waivers against a
subject+testcase, rather than a result_id, we wrote a schema
migration which just drops the old column.
Now that result_id it is used we needed to make some
changes for backward compatibility.

---

diff --git a/waiverdb/migrations/versions/f2772c2c64a6_waive_absence_of_result.py b/waiverdb/migrations/versions/f2772c2c64a6_waive_absence_of_result.py
index 7d3537f..8238b1d 100644
--- a/waiverdb/migrations/versions/f2772c2c64a6_waive_absence_of_result.py
+++ b/waiverdb/migrations/versions/f2772c2c64a6_waive_absence_of_result.py
@@ -8,6 +8,10 @@ Create Date: 2017-12-04 10:03:54.792758
 
 from alembic import op
 import sqlalchemy as sa
+import requests
+
+from waiverdb.api_v1 import get_resultsdb_result
+from waiverdb.models import db, Waiver
 
 
 # revision identifiers, used by Alembic.
@@ -15,23 +19,54 @@ revision = 'f2772c2c64a6'
 down_revision = '0a74cdab732a'
 
 
+def convert_id_to_subject_and_testcase(result_id):
+    try:
+        result = get_resultsdb_result(result_id)
+    except requests.HTTPError as e:
+        if e.response.status_code == 404:
+            raise RuntimeError('Result id %s not found in Resultsdb' % (result_id))
+        else:
+            raise RuntimeError('Failed looking up result in Resultsdb: %s' % e)
+    except Exception as e:
+        raise RuntimeError('Failed looking up result in Resultsdb: %s' % e)
+    if 'original_spec_nvr' in result['data']:
+        subject = {'original_spec_nvr': result['data']['original_spec_nvr'][0]}
+    else:
+        if result['data']['type'][0] == 'koji_build' or \
+           result['data']['type'][0] == 'bodhi_update':
+            SUBJECT_KEYS = ['item', 'type']
+            subject = dict([(k, v[0]) for k, v in result['data'].items()
+                            if k in SUBJECT_KEYS])
+        else:
+            raise RuntimeError('Unable to determine subject for result id %s' % (result_id))
+    testcase = result['testcase']['name']
+    return (subject, testcase)
+
+
 def upgrade():
     op.add_column('waiver', sa.Column('subject', sa.Text(), nullable=True, index=True))
     op.add_column('waiver', sa.Column('testcase', sa.Text(), nullable=True, index=True))
 
+    # querying resultsdb for the corresponding subject/testcase for each result_id
+    waivers = Waiver.query.all()
+    for waiver in waivers:
+        subject, testcase = convert_id_to_subject_and_testcase(waiver.result_id)
+        waiver.subject = subject
+        waiver.testcase = testcase
+        db.session.commit()
+
     # SQLite has some problem in dropping/altering columns.
     # So in this way Alembic should do some behind the scenes
     # with: make new table - copy data - drop old table - rename new table
     with op.batch_alter_table('waiver') as batch_op:
         batch_op.alter_column('subject', nullable=False)
         batch_op.alter_column('testcase', nullable=False)
-        batch_op.drop_column('result_id')
+        batch_op.alter_column('result_id', nullable=True)
 
 
 def downgrade():
-    op.add_column('waiver', sa.Column('result_id', sa.INTEGER(), nullable=True))
-
-    with op.batch_alter_table('waiver') as batch_op:
-        batch_op.drop_column('testcase')
-        batch_op.drop_column('subject')
-        batch_op.alter_column('result_id', nullable=False)
+    # It shouldn't be possible to downgrade this change.
+    # Because the result_id field will not be populated with data anymore.
+    # If the user tries to downgrade "result_id" should be not null once again
+    # like in the old version of the schema, but the value is not longer available
+    raise RuntimeError('Irreversible migration')
diff --git a/waiverdb/models/waivers.py b/waiverdb/models/waivers.py
index c45c2a5..094994f 100644
--- a/waiverdb/models/waivers.py
+++ b/waiverdb/models/waivers.py
@@ -8,6 +8,7 @@ from sqlalchemy_utils import JSONType
 
 class Waiver(db.Model):
     id = db.Column(db.Integer, primary_key=True)
+    result_id = db.Column(db.Integer, nullable=True)
     subject = db.Column(JSONType, nullable=False, index=True)
     testcase = db.Column(db.Text, nullable=False, index=True)
     username = db.Column(db.String(255), nullable=False)
@@ -28,9 +29,9 @@ class Waiver(db.Model):
         self.proxied_by = proxied_by
 
     def __repr__(self):
-        return '%s(subject=%r, testcase=%r, username=%r, product_version=%r, waived=%r)' % \
-               (self.__class__.__name__, self.subject, self.testcase, self.username,
-                self.product_version, self.waived)
+        return '%s(result_id=%r, subject=%r, testcase=%r, username=%r, product_version=%r,\
+                waived=%r)' % (self.__class__.__name__, self.result_id, self.subject, self.testcase,
+                               self.username, self.product_version, self.waived)
 
     @classmethod
     def by_results(cls, query, results):