Re: [Django] #24303: Not all models available in custom data migration

[Django]

#24303: Not all models available in custom data migration
-+--
 Reporter:  grandfatha   |Owner:  nobody
 Type:  Bug  |   Status:  closed
Component:  Migrations   |  Version:  1.7
 Severity:  Normal   |   Resolution:  worksforme
 Keywords:  data migrations  | Triage Stage:  Unreviewed
Has patch:  0|  Needs documentation:  0
  Needs tests:  0|  Patch needs improvement:  0
Easy pickings:  0|UI/UX:  0
-+--

Comment (by grandfatha):

 Oh god that was a bad idea. If anyone ever reads this: Use a real
 migration instead of "__first__" if your data migration requires fields
 that will be added after "__first__". It might sound nice to not depend on
 a specific version, but it can cause failure.

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Re: [Django] #24303: Not all models available in custom data migration

[Django]

#24303: Not all models available in custom data migration
-+--
 Reporter:  grandfatha   |Owner:  nobody
 Type:  Bug  |   Status:  closed
Component:  Migrations   |  Version:  1.7
 Severity:  Normal   |   Resolution:  worksforme
 Keywords:  data migrations  | Triage Stage:  Unreviewed
Has patch:  0|  Needs documentation:  0
  Needs tests:  0|  Patch needs improvement:  0
Easy pickings:  0|UI/UX:  0
-+--

Comment (by grandfatha):

 When trying this within my app, I got:

   File ".../site-packages/django/db/migrations/graph.py", line 46, in
 add_dependency
 "Migration %s dependencies reference nonexistent parent node %r" %
 (migration, parent)
 KeyError: u"Migration items.0006_auto_20150212_1138 dependencies reference
 nonexistent parent node (u'attributes', u'0001_initial.py')"


 I changed it to:

 {{{

 class Migration(migrations.Migration):

 dependencies = [
 ('items', '0005_probe_is_active'),
 ('attributes', '__first__'),
 ('actions', '__first__'),
 ]

 operations = [
migrations.RunPython(code=forwards)
 ]

 }}}

 Then it worked.

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Ticket URL: 
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Re: [Django] #24303: Not all models available in custom data migration

[Django]

#24303: Not all models available in custom data migration
-+--
 Reporter:  grandfatha   |Owner:  nobody
 Type:  Bug  |   Status:  closed
Component:  Migrations   |  Version:  1.7
 Severity:  Normal   |   Resolution:  worksforme
 Keywords:  data migrations  | Triage Stage:  Unreviewed
Has patch:  0|  Needs documentation:  0
  Needs tests:  0|  Patch needs improvement:  0
Easy pickings:  0|UI/UX:  0
-+--

Comment (by grandfatha):

 Thank you for your input!

 So I should depend on the first or latest migration of all the apps that I
 use?

 In the case as described above, would as shown below be the correct way to
 go?

 {{{
 class Migration(migrations.Migration):

 dependencies = [
 ('items','0001_initial.py'),
 ('attributes','0001_initial.py'),
 ('actions','0001_initial.py'),
 ]

 operations = [
 migrations.RunPython(code=forwards)
 ]

 }}}

--
Ticket URL: 
Django 
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Re: [Django] #24303: Not all models available in custom data migration

[Django]

#24303: Not all models available in custom data migration
-+--
 Reporter:  grandfatha   |Owner:  nobody
 Type:  Bug  |   Status:  closed
Component:  Migrations   |  Version:  1.7
 Severity:  Normal   |   Resolution:  worksforme
 Keywords:  data migrations  | Triage Stage:  Unreviewed
Has patch:  0|  Needs documentation:  0
  Needs tests:  0|  Patch needs improvement:  0
Easy pickings:  0|UI/UX:  0
-+--
Changes (by knbk):

 * status:  new => closed
 * needs_better_patch:   => 0
 * resolution:   => worksforme
 * needs_tests:   => 0
 * needs_docs:   => 0


Comment:

 It works fine for me. Make sure your custom migration has all the apps
 that you use in your `RunPython` function listed in its dependencies, or
 the app indeed won't be loaded.

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Ticket URL: 
Django 
The Web framework for perfectionists with deadlines.

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[Django] #24303: Not all models available in custom data migration

[Django]

#24303: Not all models available in custom data migration
+-
 Reporter:  grandfatha  |  Owner:  nobody
 Type:  Bug | Status:  new
Component:  Migrations  |Version:  1.7
 Severity:  Normal  |   Keywords:  data migrations
 Triage Stage:  Unreviewed  |  Has patch:  0
Easy pickings:  0   |  UI/UX:  0
+-
 I am building an EAV driven database. I need to write a complex data
 migration, which shall move the values an actual model field onto an
 attribute/value model instance. The code cannot be disclosed, but a
 simplified version looks like this:

 app: actions


 {{{
 class Action(models.Models):
 name = models.CharField(...)
 values = generic.GenericRelation(Value, content_type_field="owner_ct",
 object_id_field="owner_id")
 items = models.ManyToManyField(Item, ...)
 }}}


 app: attributes

 {{{
 class Attribute(models.Model):
 name = models.CharField(...)
 



 class Value(models.Model)
 value = models.CharField (...)
 attribute = models.ForeignKe(Attribute, ...)
 owner_id = models.PositiveIntegerField(blank=True, null=True)
 owner_ct = models.ForeignKey(ContentType, )
 owner = generic.GenericForeignKey(ct_field='owner_ct',
 fk_field='owner_id')

 }}}


 app: items


 {{{
 class Item(MPTTModel):
 user_label = models.CharField(...)
 }}}



 Basically the goal is to create an Attribute for the field "user_label" of
 class Item and migrate all user_label values onto a Value instance that
 are connected to the Item through the Action model.

 When I try to create a data migration for this, only some of the models
 are loaded in the app registry, depending on where I put the data
 migration. When I try to load them using "get_model" only parts of all my
 models within my app are loaded..



 {{{
 def forwards(apps, schema_editor):
 Value = apps.get_model('attributes','Value')
 Attribute = apps.get_model('attributes','Attribute')
 Action = apps.get_model('actions','Action')
 Item = apps.get_model('items','Item')
 .

 class Migration(migrations.Migration):

 dependencies = [
 ('),
 ]

 operations = [
 migrations.RunPython(code=forwards)
 ]
 }}}



 I cannot run the database access code, because the instances returned by
 get_model are missing


 My current workaround:

 Create a management command that runs the code necessary to fulfill the
 desired side-effects of the data migration. This works, because I have
 full access to all of my models.

 The downside of this approach is that you have to remember when to run the
 management command. I cannot create a schema migration right now to remove
 the soon to be unused "user_label" charfield, because I need to run the
 management command in between the migrations manually.


 Am I doing something wrong? How can I create a data migration that has
 access to all models just like management commands do?

--
Ticket URL: 
Django 
The Web framework for perfectionists with deadlines.

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