[4/6] Begin live migration of diff and pull_url to Submission

This patch contains 2 migrations:

0037_prepare_old_diff_pull_url:
 - renames Patch's 'diff' to 'old_diff', while not affecting the db
 - likewise 'pull_url' to 'old_pull_url'
This does no SQL changes, which you can verify with
python manage.py sqlmigrate patchwork 0037

0038_submission_new_diff_pull_url:
 - creates a diff column in Submission, accessible via new_diff
 - likewise pull_url as new_pull_url

livemigrate-v22-v23: (the version numbers are a bit arbitrary)
 - copies data from old_{pull_url,diff} to new_{pull_url,diff}
   as required. Can be run on a _running instance_ of patchwork.

The rest of the code provides a bunch of pretty ugly glue code.
It assumes both migrations have been run, and then allows pw to:
 - read old data from old_{pull_url,diff}
 - store new data in both the old and new fields

The idea is that you should be able to:
 - bring down pw
 - apply this
 - do two fast migrations (one with no SQL, one that adds two columns)
 - restart patchwork, restart ingesting mail
 - do the live migration over time
 - proceed to the next patch

By storing the data in duplicate, the hope is that you can
back out the new code at any point and still have all of your data.

Signed-off-by: Daniel Axtens <dja@axtens.net>
---
 patchwork/api/patch.py                        | 10 +-
 .../commands/livemigrate-v22-v23.py           | 35 +++++++
 .../0037_prepare_old_diff_pull_url.py         | 35 +++++++
 .../0038_submission_new_diff_pull_url.py      | 25 +++++
 patchwork/models.py                           | 93 ++++++++++++++++++-
 patchwork/views/xmlrpc.py                     |  5 +-
 6 files changed, 197 insertions(+), 6 deletions(-)
 create mode 100644 patchwork/management/commands/livemigrate-v22-v23.py
 create mode 100644 patchwork/migrations/0037_prepare_old_diff_pull_url.py
 create mode 100644 patchwork/migrations/0038_submission_new_diff_pull_url.py

Daniel Axtens <dja@axtens.net> writes:

> This patch contains 2 migrations:
>
> 0037_prepare_old_diff_pull_url:
>  - renames Patch's 'diff' to 'old_diff', while not affecting the db
>  - likewise 'pull_url' to 'old_pull_url'
> This does no SQL changes, which you can verify with
> python manage.py sqlmigrate patchwork 0037
>
> 0038_submission_new_diff_pull_url:
>  - creates a diff column in Submission, accessible via new_diff
>  - likewise pull_url as new_pull_url
>
> livemigrate-v22-v23: (the version numbers are a bit arbitrary)
>  - copies data from old_{pull_url,diff} to new_{pull_url,diff}
>    as required. Can be run on a _running instance_ of patchwork.
>
> The rest of the code provides a bunch of pretty ugly glue code.
> It assumes both migrations have been run, and then allows pw to:
>  - read old data from old_{pull_url,diff}
>  - store new data in both the old and new fields
>
> The idea is that you should be able to:
>  - bring down pw
>  - apply this
>  - do two fast migrations (one with no SQL, one that adds two columns)
>  - restart patchwork, restart ingesting mail
>  - do the live migration over time
>  - proceed to the next patch
>
> By storing the data in duplicate, the hope is that you can
> back out the new code at any point and still have all of your data.
>
> Signed-off-by: Daniel Axtens <dja@axtens.net>
> ---
>  patchwork/api/patch.py                        | 10 +-
>  .../commands/livemigrate-v22-v23.py           | 35 +++++++
>  .../0037_prepare_old_diff_pull_url.py         | 35 +++++++
>  .../0038_submission_new_diff_pull_url.py      | 25 +++++
>  patchwork/models.py                           | 93 ++++++++++++++++++-
>  patchwork/views/xmlrpc.py                     |  5 +-
>  6 files changed, 197 insertions(+), 6 deletions(-)
>  create mode 100644 patchwork/management/commands/livemigrate-v22-v23.py
>  create mode 100644 patchwork/migrations/0037_prepare_old_diff_pull_url.py
>  create mode 100644 patchwork/migrations/0038_submission_new_diff_pull_url.py
>
> diff --git a/patchwork/api/patch.py b/patchwork/api/patch.py
> index c9360308a56a..3866f92fe3dc 100644
> --- a/patchwork/api/patch.py
> +++ b/patchwork/api/patch.py
> @@ -181,11 +181,15 @@ class PatchList(ListAPIView):
>      ordering = 'id'
>  
>      def get_queryset(self):
> -        return Patch.objects.all()\
> +        qs = Patch.objects.all()\
>              .prefetch_related('check_set')\
>              .select_related('project', 'state', 'submitter', 'delegate',
> -                            'series')\
> -            .defer('content', 'diff', 'headers')
> +                            'series')
> +        if hasattr(Patch, 'old_diff'):
> +            qs.defer('content', 'old_diff', 'headers')
> +        else:
> +            qs.defer('content', 'submission_ptr__new_diff', 'headers')
> +        return qs
>  
>  
>  class PatchDetail(RetrieveUpdateAPIView):
> diff --git a/patchwork/management/commands/livemigrate-v22-v23.py b/patchwork/management/commands/livemigrate-v22-v23.py
> new file mode 100644
> index 000000000000..1079fb2f3997
> --- /dev/null
> +++ b/patchwork/management/commands/livemigrate-v22-v23.py
> @@ -0,0 +1,35 @@
> +# Patchwork - automated patch tracking system
> +# Copyright (C) 2019 IBM Corporation
> +#  Author: Daniel Axtens <dja@axtens.net>
> +#
> +# SPDX-License-Identifier: GPL-2.0-or-later
> +
> +from django.core.management.base import BaseCommand
> +from django.db.models import Q
> +
> +from patchwork.models import Patch
> +from patchwork.models import Submission
> +
> +
> +class Command(BaseCommand):
> +    help = 'Do the live migration for flattening patches'
> +
> +    def handle(self, *args, **options):
> +        if not hasattr(Submission, 'new_diff'):
> +            print("Submission model is missing 'new_diff'. Have you applied the migration to add it?")
> +            return
> +
> +        diffs = Q(old_diff__isnull=False, submission_ptr__new_diff__isnull=True)
> +        pull_urls = Q(old_pull_url__isnull=False, submission_ptr__new_pull_url__isnull=True)
> +        query = Patch.objects.filter(diffs | pull_urls)
> +
> +        count = query.count()
> +
> +        for i, patch in enumerate(query.iterator()):
> +            patch.new_diff = patch.old_diff
> +            patch.new_pull_url = patch.old_pull_url
> +            patch.save()
> +            if (i % 10) == 0:
> +                self.stdout.write('%06d/%06d\r' % (i, count), ending='')
> +                self.stdout.flush()
> +        self.stdout.write('\ndone')
> diff --git a/patchwork/migrations/0037_prepare_old_diff_pull_url.py b/patchwork/migrations/0037_prepare_old_diff_pull_url.py
> new file mode 100644
> index 000000000000..83fd1beaac9c
> --- /dev/null
> +++ b/patchwork/migrations/0037_prepare_old_diff_pull_url.py
> @@ -0,0 +1,35 @@
> +# -*- coding: utf-8 -*-
> +# Generated by Django 1.11.24 on 2019-09-18 01:49
> +from __future__ import unicode_literals
> +
> +from django.db import migrations, models
> +
> +
> +class Migration(migrations.Migration):
> +
> +    dependencies = [
> +        ('patchwork', '0036_project_commit_url_format'),
> +    ]
> +
> +    operations = [
> +        migrations.AlterField(
> +            model_name='patch',
> +            name='diff',
> +            field=models.TextField(blank=True, db_column='diff', null=True),
> +        ),
> +        migrations.RenameField(
> +            model_name='patch',
> +            old_name='diff',
> +            new_name='old_diff',
> +        ),
> +        migrations.AlterField(
> +            model_name='patch',
> +            name='pull_url',
> +            field=models.CharField(blank=True, db_column='pull_url', max_length=255, null=True),
> +        ),
> +        migrations.RenameField(
> +            model_name='patch',
> +            old_name='pull_url',
> +            new_name='old_pull_url',
> +        ),
> +    ]
> diff --git a/patchwork/migrations/0038_submission_new_diff_pull_url.py b/patchwork/migrations/0038_submission_new_diff_pull_url.py
> new file mode 100644
> index 000000000000..094854d863cb
> --- /dev/null
> +++ b/patchwork/migrations/0038_submission_new_diff_pull_url.py
> @@ -0,0 +1,25 @@
> +# -*- coding: utf-8 -*-
> +# Generated by Django 1.11.24 on 2019-09-18 01:54
> +from __future__ import unicode_literals
> +
> +from django.db import migrations, models
> +
> +
> +class Migration(migrations.Migration):
> +
> +    dependencies = [
> +        ('patchwork', '0037_prepare_old_diff_pull_url'),
> +    ]
> +
> +    operations = [
> +        migrations.AddField(
> +            model_name='submission',
> +            name='new_diff',
> +            field=models.TextField(blank=True, db_column='diff', null=True),
> +        ),
> +        migrations.AddField(
> +            model_name='submission',
> +            name='new_pull_url',
> +            field=models.CharField(blank=True, db_column='pull_url', max_length=255, null=True),
> +        ),
> +    ]
> diff --git a/patchwork/models.py b/patchwork/models.py
> index 32d1b3c2adc5..31f459e1a126 100644
> --- a/patchwork/models.py
> +++ b/patchwork/models.py
> @@ -367,6 +367,11 @@ class Submission(FilenameMixin, EmailMixin, models.Model):
>  
>      name = models.CharField(max_length=255)
>  
> +    # patch
> +    new_diff = models.TextField(null=True, blank=True, db_column='diff')
> +    new_pull_url = models.CharField(max_length=255, null=True, blank=True, db_column='pull_url')
> +
> +
>      @property
>      def list_archive_url(self):
>          if not self.project.list_archive_url_format:
> @@ -410,9 +415,9 @@ class CoverLetter(Submission):
>  class Patch(Submission):
>      # patch metadata
>  
> -    diff = models.TextField(null=True, blank=True)
> +    old_diff = models.TextField(null=True, blank=True, db_column='diff')
>      commit_ref = models.CharField(max_length=255, null=True, blank=True)
> -    pull_url = models.CharField(max_length=255, null=True, blank=True)
> +    old_pull_url = models.CharField(max_length=255, null=True, blank=True, db_column='pull_url')
>      tags = models.ManyToManyField(Tag, through=PatchTag)
>  
>      # patchwork metadata
> @@ -479,6 +484,20 @@ class Patch(Submission):
>  
>          super(Patch, self).save(**kwargs)
>  
> +        # we don't have to worry about duplicating to the
> +        # old fields: the setters do this for us.
> +        if hasattr(self, '_diff'):
> +            if hasattr(self.submission_ptr, 'new_diff'):
> +                self.new_diff = self._diff
> +                self.submission_ptr.save()
> +            del self._diff
> +
> +        if hasattr(self, '_pull_url'):
> +            if hasattr(self.submission_ptr, 'new_pull_url'):
> +                self.new_pull_url = self._diff
> +                self.submission_ptr.save()
> +            del self._pull_url
> +
>          self.refresh_tag_counts()
>  
>      def is_editable(self, user):
> @@ -602,6 +621,76 @@ class Patch(Submission):
>          ]
>  
>  
> +    # transition goop
> +    @property
> +    def diff(self):
> +        # three options:
> +        # it's sitting around in our cached storage
> +        # new field is not null
> +        # old has field
> +        # no point in null checking old
> +        if hasattr(self, '_diff'):
> +            return self._diff
> +        try:
> +            if self.submission_ptr.new_diff is not None:
> +                return self.submission_ptr.new_diff
> +        except:
> +            pass
> +        if hasattr(self, 'old_diff'):
> +            return self.old_diff
> +        return None
> +
> +    @diff.setter
> +    def diff(self, value):
> +        try:
> +            self.submission_ptr.diff = value
This should be new_diff, but the caching saved us.

Working now on moving series around.

Regards,
Daniel

> +        except:
> +            self._diff = value
> +        if hasattr(self, 'old_diff'):
> +            self.old_diff = value
> +
> +    @property
> +    def pull_url(self):
> +        if hasattr(self, '_pull_url'):
> +            return self._pull_url
> +        try:
> +            if self.submission_ptr.new_pull_url is not None:
> +                return self.submission_ptr.new_pull_url
> +        except:
> +            pass
> +        if hasattr(self, 'old_pull_url'):
> +            return self.old_pull_url
> +        return None
> +
> +    @pull_url.setter
> +    def pull_url(self, value):
> +        try:
> +            self.submission_ptr.pull_url = value
> +        except:
> +            self._diff = value
> +        if hasattr(self, 'old_pull_url'):
> +            self.old_pull_url = value
> +
> +
> +    def __init__(self, *args, **kwargs):
> +        diff = None
> +        if 'diff' in kwargs:
> +            diff = kwargs['diff']
> +            del kwargs['diff']
> +
> +        pull_url = None
> +        if 'pull_url' in kwargs:
> +            pull_url = kwargs['pull_url']
> +            del kwargs['pull_url']
> +
> +        super(Patch, self).__init__(*args, **kwargs)
> +
> +        if diff:
> +            self.diff = diff
> +        if pull_url:
> +            self.pull_url = pull_url
> +
> +
>  class Comment(EmailMixin, models.Model):
>      # parent
>  
> diff --git a/patchwork/views/xmlrpc.py b/patchwork/views/xmlrpc.py
> index f60725044ebe..a2e3d8985dd7 100644
> --- a/patchwork/views/xmlrpc.py
> +++ b/patchwork/views/xmlrpc.py
> @@ -569,7 +569,10 @@ def patch_list(filt=None):
>      # Only extract the relevant fields. This saves a big db load as we
>      # no longer fetch content/headers/etc for potentially every patch
>      # in a project.
> -    patches = patches.defer('content', 'headers', 'diff')
> +    if hasattr(Patch, 'old_diff'):
> +        patches = patches.defer('content', 'headers', 'old_diff')
> +    else:
> +        patches = patches.defer('content', 'headers', 'submission_ptr__new_diff')
>  
>      return _get_objects(patch_to_dict, patches, max_count)
>  
> -- 
> 2.20.1

Daniel Axtens <dja@axtens.net> writes:

> This patch contains 2 migrations:
>
> 0037_prepare_old_diff_pull_url:
>  - renames Patch's 'diff' to 'old_diff', while not affecting the db
>  - likewise 'pull_url' to 'old_pull_url'
> This does no SQL changes, which you can verify with
> python manage.py sqlmigrate patchwork 0037
>
> 0038_submission_new_diff_pull_url:
>  - creates a diff column in Submission, accessible via new_diff
>  - likewise pull_url as new_pull_url
>
> livemigrate-v22-v23: (the version numbers are a bit arbitrary)
>  - copies data from old_{pull_url,diff} to new_{pull_url,diff}
>    as required. Can be run on a _running instance_ of patchwork.
>
> The rest of the code provides a bunch of pretty ugly glue code.
> It assumes both migrations have been run, and then allows pw to:
>  - read old data from old_{pull_url,diff}
>  - store new data in both the old and new fields

It turns out this is way, way, overcomplicating things. I think I had
twisted myself in knots by not properly splitting out schema migration
and data migration in my mental model of things. Anyway, we can do this
much more simply:

 - don't rename the field in Patch
 - add a new field in Submission called new_blah
 - make save() copy the data into Submission
 - then the next patch drops the fields in Patch and renames the fields
   in Submission.

I figured this out trying to extend my approach to migrating series and
number. Once I get that sorted out, I'll send new patches out.

Kind regards,
Daniel

>
> The idea is that you should be able to:
>  - bring down pw
>  - apply this
>  - do two fast migrations (one with no SQL, one that adds two columns)
>  - restart patchwork, restart ingesting mail
>  - do the live migration over time
>  - proceed to the next patch
>
> By storing the data in duplicate, the hope is that you can
> back out the new code at any point and still have all of your data.
>
> Signed-off-by: Daniel Axtens <dja@axtens.net>
> ---
>  patchwork/api/patch.py                        | 10 +-
>  .../commands/livemigrate-v22-v23.py           | 35 +++++++
>  .../0037_prepare_old_diff_pull_url.py         | 35 +++++++
>  .../0038_submission_new_diff_pull_url.py      | 25 +++++
>  patchwork/models.py                           | 93 ++++++++++++++++++-
>  patchwork/views/xmlrpc.py                     |  5 +-
>  6 files changed, 197 insertions(+), 6 deletions(-)
>  create mode 100644 patchwork/management/commands/livemigrate-v22-v23.py
>  create mode 100644 patchwork/migrations/0037_prepare_old_diff_pull_url.py
>  create mode 100644 patchwork/migrations/0038_submission_new_diff_pull_url.py
>
> diff --git a/patchwork/api/patch.py b/patchwork/api/patch.py
> index c9360308a56a..3866f92fe3dc 100644
> --- a/patchwork/api/patch.py
> +++ b/patchwork/api/patch.py
> @@ -181,11 +181,15 @@ class PatchList(ListAPIView):
>      ordering = 'id'
>  
>      def get_queryset(self):
> -        return Patch.objects.all()\
> +        qs = Patch.objects.all()\
>              .prefetch_related('check_set')\
>              .select_related('project', 'state', 'submitter', 'delegate',
> -                            'series')\
> -            .defer('content', 'diff', 'headers')
> +                            'series')
> +        if hasattr(Patch, 'old_diff'):
> +            qs.defer('content', 'old_diff', 'headers')
> +        else:
> +            qs.defer('content', 'submission_ptr__new_diff', 'headers')
> +        return qs
>  
>  
>  class PatchDetail(RetrieveUpdateAPIView):
> diff --git a/patchwork/management/commands/livemigrate-v22-v23.py b/patchwork/management/commands/livemigrate-v22-v23.py
> new file mode 100644
> index 000000000000..1079fb2f3997
> --- /dev/null
> +++ b/patchwork/management/commands/livemigrate-v22-v23.py
> @@ -0,0 +1,35 @@
> +# Patchwork - automated patch tracking system
> +# Copyright (C) 2019 IBM Corporation
> +#  Author: Daniel Axtens <dja@axtens.net>
> +#
> +# SPDX-License-Identifier: GPL-2.0-or-later
> +
> +from django.core.management.base import BaseCommand
> +from django.db.models import Q
> +
> +from patchwork.models import Patch
> +from patchwork.models import Submission
> +
> +
> +class Command(BaseCommand):
> +    help = 'Do the live migration for flattening patches'
> +
> +    def handle(self, *args, **options):
> +        if not hasattr(Submission, 'new_diff'):
> +            print("Submission model is missing 'new_diff'. Have you applied the migration to add it?")
> +            return
> +
> +        diffs = Q(old_diff__isnull=False, submission_ptr__new_diff__isnull=True)
> +        pull_urls = Q(old_pull_url__isnull=False, submission_ptr__new_pull_url__isnull=True)
> +        query = Patch.objects.filter(diffs | pull_urls)
> +
> +        count = query.count()
> +
> +        for i, patch in enumerate(query.iterator()):
> +            patch.new_diff = patch.old_diff
> +            patch.new_pull_url = patch.old_pull_url
> +            patch.save()
> +            if (i % 10) == 0:
> +                self.stdout.write('%06d/%06d\r' % (i, count), ending='')
> +                self.stdout.flush()
> +        self.stdout.write('\ndone')
> diff --git a/patchwork/migrations/0037_prepare_old_diff_pull_url.py b/patchwork/migrations/0037_prepare_old_diff_pull_url.py
> new file mode 100644
> index 000000000000..83fd1beaac9c
> --- /dev/null
> +++ b/patchwork/migrations/0037_prepare_old_diff_pull_url.py
> @@ -0,0 +1,35 @@
> +# -*- coding: utf-8 -*-
> +# Generated by Django 1.11.24 on 2019-09-18 01:49
> +from __future__ import unicode_literals
> +
> +from django.db import migrations, models
> +
> +
> +class Migration(migrations.Migration):
> +
> +    dependencies = [
> +        ('patchwork', '0036_project_commit_url_format'),
> +    ]
> +
> +    operations = [
> +        migrations.AlterField(
> +            model_name='patch',
> +            name='diff',
> +            field=models.TextField(blank=True, db_column='diff', null=True),
> +        ),
> +        migrations.RenameField(
> +            model_name='patch',
> +            old_name='diff',
> +            new_name='old_diff',
> +        ),
> +        migrations.AlterField(
> +            model_name='patch',
> +            name='pull_url',
> +            field=models.CharField(blank=True, db_column='pull_url', max_length=255, null=True),
> +        ),
> +        migrations.RenameField(
> +            model_name='patch',
> +            old_name='pull_url',
> +            new_name='old_pull_url',
> +        ),
> +    ]
> diff --git a/patchwork/migrations/0038_submission_new_diff_pull_url.py b/patchwork/migrations/0038_submission_new_diff_pull_url.py
> new file mode 100644
> index 000000000000..094854d863cb
> --- /dev/null
> +++ b/patchwork/migrations/0038_submission_new_diff_pull_url.py
> @@ -0,0 +1,25 @@
> +# -*- coding: utf-8 -*-
> +# Generated by Django 1.11.24 on 2019-09-18 01:54
> +from __future__ import unicode_literals
> +
> +from django.db import migrations, models
> +
> +
> +class Migration(migrations.Migration):
> +
> +    dependencies = [
> +        ('patchwork', '0037_prepare_old_diff_pull_url'),
> +    ]
> +
> +    operations = [
> +        migrations.AddField(
> +            model_name='submission',
> +            name='new_diff',
> +            field=models.TextField(blank=True, db_column='diff', null=True),
> +        ),
> +        migrations.AddField(
> +            model_name='submission',
> +            name='new_pull_url',
> +            field=models.CharField(blank=True, db_column='pull_url', max_length=255, null=True),
> +        ),
> +    ]
> diff --git a/patchwork/models.py b/patchwork/models.py
> index 32d1b3c2adc5..31f459e1a126 100644
> --- a/patchwork/models.py
> +++ b/patchwork/models.py
> @@ -367,6 +367,11 @@ class Submission(FilenameMixin, EmailMixin, models.Model):
>  
>      name = models.CharField(max_length=255)
>  
> +    # patch
> +    new_diff = models.TextField(null=True, blank=True, db_column='diff')
> +    new_pull_url = models.CharField(max_length=255, null=True, blank=True, db_column='pull_url')
> +
> +
>      @property
>      def list_archive_url(self):
>          if not self.project.list_archive_url_format:
> @@ -410,9 +415,9 @@ class CoverLetter(Submission):
>  class Patch(Submission):
>      # patch metadata
>  
> -    diff = models.TextField(null=True, blank=True)
> +    old_diff = models.TextField(null=True, blank=True, db_column='diff')
>      commit_ref = models.CharField(max_length=255, null=True, blank=True)
> -    pull_url = models.CharField(max_length=255, null=True, blank=True)
> +    old_pull_url = models.CharField(max_length=255, null=True, blank=True, db_column='pull_url')
>      tags = models.ManyToManyField(Tag, through=PatchTag)
>  
>      # patchwork metadata
> @@ -479,6 +484,20 @@ class Patch(Submission):
>  
>          super(Patch, self).save(**kwargs)
>  
> +        # we don't have to worry about duplicating to the
> +        # old fields: the setters do this for us.
> +        if hasattr(self, '_diff'):
> +            if hasattr(self.submission_ptr, 'new_diff'):
> +                self.new_diff = self._diff
> +                self.submission_ptr.save()
> +            del self._diff
> +
> +        if hasattr(self, '_pull_url'):
> +            if hasattr(self.submission_ptr, 'new_pull_url'):
> +                self.new_pull_url = self._diff
> +                self.submission_ptr.save()
> +            del self._pull_url
> +
>          self.refresh_tag_counts()
>  
>      def is_editable(self, user):
> @@ -602,6 +621,76 @@ class Patch(Submission):
>          ]
>  
>  
> +    # transition goop
> +    @property
> +    def diff(self):
> +        # three options:
> +        # it's sitting around in our cached storage
> +        # new field is not null
> +        # old has field
> +        # no point in null checking old
> +        if hasattr(self, '_diff'):
> +            return self._diff
> +        try:
> +            if self.submission_ptr.new_diff is not None:
> +                return self.submission_ptr.new_diff
> +        except:
> +            pass
> +        if hasattr(self, 'old_diff'):
> +            return self.old_diff
> +        return None
> +
> +    @diff.setter
> +    def diff(self, value):
> +        try:
> +            self.submission_ptr.diff = value
> +        except:
> +            self._diff = value
> +        if hasattr(self, 'old_diff'):
> +            self.old_diff = value
> +
> +    @property
> +    def pull_url(self):
> +        if hasattr(self, '_pull_url'):
> +            return self._pull_url
> +        try:
> +            if self.submission_ptr.new_pull_url is not None:
> +                return self.submission_ptr.new_pull_url
> +        except:
> +            pass
> +        if hasattr(self, 'old_pull_url'):
> +            return self.old_pull_url
> +        return None
> +
> +    @pull_url.setter
> +    def pull_url(self, value):
> +        try:
> +            self.submission_ptr.pull_url = value
> +        except:
> +            self._diff = value
> +        if hasattr(self, 'old_pull_url'):
> +            self.old_pull_url = value
> +
> +
> +    def __init__(self, *args, **kwargs):
> +        diff = None
> +        if 'diff' in kwargs:
> +            diff = kwargs['diff']
> +            del kwargs['diff']
> +
> +        pull_url = None
> +        if 'pull_url' in kwargs:
> +            pull_url = kwargs['pull_url']
> +            del kwargs['pull_url']
> +
> +        super(Patch, self).__init__(*args, **kwargs)
> +
> +        if diff:
> +            self.diff = diff
> +        if pull_url:
> +            self.pull_url = pull_url
> +
> +
>  class Comment(EmailMixin, models.Model):
>      # parent
>  
> diff --git a/patchwork/views/xmlrpc.py b/patchwork/views/xmlrpc.py
> index f60725044ebe..a2e3d8985dd7 100644
> --- a/patchwork/views/xmlrpc.py
> +++ b/patchwork/views/xmlrpc.py
> @@ -569,7 +569,10 @@ def patch_list(filt=None):
>      # Only extract the relevant fields. This saves a big db load as we
>      # no longer fetch content/headers/etc for potentially every patch
>      # in a project.
> -    patches = patches.defer('content', 'headers', 'diff')
> +    if hasattr(Patch, 'old_diff'):
> +        patches = patches.defer('content', 'headers', 'old_diff')
> +    else:
> +        patches = patches.defer('content', 'headers', 'submission_ptr__new_diff')
>  
>      return _get_objects(patch_to_dict, patches, max_count)
>  
> -- 
> 2.20.1