gfks
: Utilites for Generic Foreign Keys¶
The lino.modlib.gkfs
plugin adds some utilities for working with Generic
Foreign Keys. You should install it if your models contain GenericForeignKey
fields or inherit from the Controllable
mixin.
A tested document¶
This is a tested document. The following instructions are used for initialization:
>>> from lino import startup
>>> startup('lino_book.projects.min9.settings.doctests')
>>> from lino.api.doctest import *
Which means that code snippets in this document are tested using the
lino_book.projects.min9
demo project.
The Controllable
mixin¶
-
class
lino.modlib.gkfs.
Controllable
¶ Mixin for models that are "controllable" by another database object.
Defines three fields
owned_type
,owned_id
andowned
. And a class attributeowner_label
.For example in
lino.modlibs.cal
, the owner of a Task or Event is some other database object that caused the task's or event's creation.Or in
lino.modlib.sales
andlino.modlib.purchases
, an invoice may cause one or several Tasks to be automatically generated when a certain payment mode is specified.Controllable objects are "governed" or "controlled" by their controller (stored in a field called
owner
): If the controller gets modified, it may decide to delete or modify some or all of her controlled objects.Non-automatic tasks always have an empty
owner
field. Some fields are read-only on an automatic Task because it makes no sense to modify them.-
owner
¶
-
owner_id
¶
-
owner_type
¶
-
update_controller_field
(cls, verbose_name=None, **kwargs)¶ Update attributes of the
owner
field and its underlying fieldsowner_id
andowner_type
.This can be used to make the controller optional (i.e. specify whether the
owner
field may be NULL). Example:class MyModel(Controllable): .... MyModel.update_controller_field(blank=False, null=False)
When verbose_name is specified, all three fields will be updated, appending " (object)" and " (type)" to
owner_id
andowner_type
respectively.
-
update_owned_instance
(self, controllable)¶ If this (acting as a controller) is itself controlled, forward the call to the controller.
-
owner_label
¶ Deprecated. This is (and always was) being ignored. Use
update_controller_field()
instead. The labels (verbose_name) of the fields owned_type, owned_id and owned are derived from this attribute which may be overridden by subclasses.
-
controller_is_optional = True
Deprecated. This is (and always was) being ignored. Use
update_controller_field()
instead.
-
The ContentTypes
table¶
The ContentTypes
table shows all models defined in your application.
>>> rt.show(gfks.ContentTypes)
==== ================== =========================
ID app label python model class name
---- ------------------ -------------------------
1 countries country
2 countries place
3 system siteconfig
4 contacts companytype
5 contacts roletype
6 contacts role
7 contacts partner
8 contacts person
9 contacts company
10 contenttypes contenttype
11 gfks helptext
...
59 notify message
60 changes change
61 comments commenttype
62 comments comment
63 comments mention
64 comments reaction
65 sessions session
==== ================== =========================
Customized help texts¶
- customized help text
A help text that has been locally overridden. It is stored in the database and loaded at startup. It can be modified by an end user with appropriate permissions.
-
class
lino.modlib.gkfs.
HelpText
¶ Django model to represent a customized help text.
>>> rt.show('gfks.HelpTexts', language="en")
========== =========================== ========================================================== ==== ===========
Field Verbose name HelpText ID Model
---------- --------------------------- ---------------------------------------------------------- ---- -----------
language Language (database field) Die Sprache, in der Dokumente ausgestellt werden sollen. 1 Partner
field Field (database field) The name of the field. 2 Help Text
========== =========================== ========================================================== ==== ===========
The language field of a partner is actually defined in
lino.mixins.Contactable
.
>>> fld = rt.models.contacts.Partner._meta.get_field('language')
>>> for m in fld.model.__mro__:
... if 'language' in m.__dict__:
... print(m)
<class 'lino.mixins.Contactable'>
These custom help texts are currently not being used. The field has the help
text defined by its prosa doc (lino_xl.lib.contacts.Partner.language
):
>>> print(fld.help_text)
The language to use when communicating with this partner.
That text is currently not translated to German:
>>> with translation.override("de"):
... print(fld.help_text)
The language to use when communicating with this partner.
Broken GFKs¶
-
class
lino.modlib.gkfs.
BrokenGFKs
¶ Shows all database objects who have a broken GeneriForeignKey field.
Fields¶
-
class
lino.modlib.gkfs.
GenericForeignKey
¶ Add verbose_name and help_text to Django's GFK.
Used by
Controllable
.
-
class
lino.modlib.gkfs.
GenericForeignKeyIdField
¶ Use this instead of models.PositiveIntegerField for fields that are part of a GFK and you want Lino to render them using a Combobox.
Used by
lino.modlib.gfks.mixins.Controllable
.Note: type_field is a mandatory argument, but you can specify anything because it is being ignored.
The gfk2lookup()
function¶
The gfk2lookup
function is mostly for
internal use, but occasionally you might want to use it in your application
code.
>>> from lino.core.utils import full_model_name as fmn
>>> from lino.core.gfks import gfk2lookup
>>> from lino.modlib.gfks.mixins import Controllable
List of models which inherit from Controllable
:
>>> print(' '.join([fmn(m) for m in rt.models_by_base(Controllable)]))
cal.Event cal.Task checkdata.Problem comments.Comment comments.Mention excerpts.Excerpt notes.Note notify.Message uploads.Upload
>>> obj = contacts.Person.objects.all()[0]
>>> d = gfk2lookup(notes.Note.owner, obj)
>>> pprint(d)
{'owner_id': 211, 'owner_type': <ContentType: Person>}
If the object has a non-integer primary key, then it cannot be target of a GFK. In this case we filter only on the content type because anyway the list will be empty. countries.Country is actually the only model with a non-integer primary key.
>>> obj = countries.Country.objects.all()[0]
>>> gfk2lookup(notes.Note.owner, obj)
{'owner_type': <ContentType: Country>}