API¶

Forms ¶

ConcurrentForm ¶

class concurrency.forms.ConcurrentForm(data=None, files=None, auto_id=u'id_%s', prefix=None, initial=None, error_class=<class 'django.forms.utils.ErrorList'>, label_suffix=None, empty_permitted=False, instance=None)[source]¶: Simple wrapper to ModelForm that try to mitigate some concurrency error. Note that is always possible have a RecordModifiedError in model.save(). Statistically form.clean() should catch most of the concurrent editing, but is good to catch RecordModifiedError in the view too.

VersionWidget ¶

class concurrency.forms.VersionWidget(attrs=None)[source]¶

Widget that show the revision number using <div>

Usually VersionField use HiddenInput as Widget to minimize the impact on the forms, in the Admin this produce a side effect to have the label Version without any value, you should use this widget to display the current revision number

Exceptions ¶

VersionChangedError ¶

class concurrency.exceptions.VersionChangedError(message, code=None, params=None)[source]¶

class concurrency.exceptions.RecordModifiedError¶

RecordModifiedError ¶

class concurrency.exceptions.RecordModifiedError(*args, **kwargs)[source]

InconsistencyError ¶

Changed in Django-Concurrency 0.7.

Warning

removed in 0.7

class concurrency.exceptions.InconsistencyError¶

VersionError ¶

class concurrency.exceptions.VersionError(message=None, code=None, params=None, *args, **kwargs)[source]¶

Admin ¶

ConcurrentModelAdmin ¶

class concurrency.admin.ConcurrentModelAdmin(model, admin_site)[source]¶

ConcurrencyActionMixin ¶

class concurrency.admin.ConcurrencyActionMixin[source]¶

ConcurrencyListEditableMixin ¶

class concurrency.admin.ConcurrencyListEditableMixin[source]¶

Middleware ¶

class concurrency.middleware.ConcurrencyMiddleware¶

ConcurrencyMiddleware ¶

concurrency.views.conflict ¶

concurrency.views.conflict(request, target=None, template_name=u'409.html')[source]¶

409 error handler.

Parameters:	request – Request template_name – 409.html target – The model to save

Helpers ¶

apply_concurrency_check()¶

New in Django-Concurrency 0.4.

Changed in Django-Concurrency 0.8.

Add concurrency check to existing classes.

Note

With Django 1.7 and the new migrations management, this utility does not work anymore. To add concurrency management to a external Model, you need to use a migration to add a VersionField to the desired Model.

Note

See demo.auth_migrations for a example how to add

IntegerVersionField to auth.Group )

operations = [
    # add version to django.contrib.auth.Group
    migrations.AddField(
        model_name='Group',
        name='version',
        field=IntegerVersionField(help_text=b'Version', default=1),
    ),
]

and put in your settings.py

MIGRATION_MODULES = {
    ...
    ...
    'auth': '<new.migration.package>',
}

disable_concurrency()¶

New in Django-Concurrency 0.6.

Context manager to temporary disable concurrency checking.

Changed in Django-Concurrency 0.9.

Starting from version 0.9, disable_concurrency can disable both at Model level or instance level, depending on the passed object. Passing Model is useful in django commands, load data or fixtures, where instance should be used by default

Changed in Django-Concurrency 1.0.

Is now possible use disable_concurrency without any argument to disable concurrency on any Model. This features has been developed to be used in django commands

examples ¶

@disable_concurrency()
def recover_view(self, request, version_id, extra_context=None):
    return super(ReversionConcurrentModelAdmin, self).recover_view(request,
                                                        version_id,
                                                        extra_context)

def test_recover():
    deleted_list = revisions.get_deleted(ReversionConcurrentModel)
    delete_version = deleted_list.get(id=5)

    with disable_concurrency(ReversionConcurrentModel):
        deleted_version.revert()

Templatetags ¶

identity ¶

concurrency.templatetags.concurrency.identity(obj)[source]¶: returns a string representing “<pk>,<version>” of the passed object

version ¶

concurrency.templatetags.concurrency.version(obj)[source]¶: returns the value of the VersionField of the passed object

is_version ¶

concurrency.templatetags.concurrency.is_version(field)[source]¶: returns True if passed argument is a VersionField instance

Test Utilties ¶

ConcurrencyTestMixin ¶

class concurrency.utils.ConcurrencyTestMixin[source]¶

Mixin class to test Models that use VersionField

this class offer a simple test scenario. Its purpose is to discover some conflict in the save() inheritance:

from concurrency.utils import ConcurrencyTestMixin
from myproject.models import MyModel

class MyModelTest(ConcurrencyTestMixin, TestCase):
    concurrency_model = TestModel0
    concurrency_kwargs = {'username': 'test'}

Signining ¶

New in Django-Concurrency 0.5.

VersionField is ‘displayed’ in the Form using an django.forms.HiddenInput widget, anyway to be sure that the version is not tampered with, its value is signed. The default VersionSigner is concurrency.forms.VersionFieldSigner that simply extends django.core.signing.Signer. If you want change your Signer you can set CONCURRENCY_FIELD_SIGNER in your settings

mysigner.py

class DummySigner():
    """ Dummy signer that simply returns the raw version value. (Simply do not sign it) """
    def sign(self, value):
        return smart_str(value)

    def unsign(self, signed_value):
        return smart_str(signed_value)

settings.py

CONCURRENCY_FIELD_SIGNER = "myapp.mysigner.DummySigner"