Question

我有这样的模特：

class Place(models.Model):
    name = models.CharField(max_length=80, db_index=True)
    city = models.ForeignKey(City)
    address = models.CharField(max_length=255, db_index=True)
    # and so on

由于我从许多来源导入它们，并且我网站的用户能够添加新的地方，我需要一种方法来从管理界面合并它们。问题是，名称不是很可靠，因为它们可以用许多不同的方式拼写等等我习惯用这样的东西：

class Place(models.Model):
    name = models.CharField(max_length=80, db_index=True) # canonical
    city = models.ForeignKey(City)
    address = models.CharField(max_length=255, db_index=True)
    # and so on

class PlaceName(models.Model):
    name = models.CharField(max_length=80, db_index=True)
    place = models.ForeignKey(Place)

像这样查询

Place.objects.get(placename__name='St Paul\'s Cathedral', city=london)

并像这样合并

class PlaceAdmin(admin.ModelAdmin):
    actions = ('merge', )

    def merge(self, request, queryset):
        main = queryset[0]
        tail = queryset[1:]

        PlaceName.objects.filter(place__in=tail).update(place=main)
        SomeModel1.objects.filter(place__in=tail).update(place=main)
        SomeModel2.objects.filter(place__in=tail).update(place=main)
        # ... etc ...

        for t in tail:
            t.delete()

        self.message_user(request, "%s is merged with other places, now you can give it a canonical name." % main)
    merge.short_description = "Merge places"

如您所见，我必须使用FK更新所有其他模型以使用新值进行放置。但这不是一个很好的解决方案，因为我必须将每个新模型添加到此列表中。

如何在删除某些对象之前“级联更新”所有外键？

或许还有其他解决方案可以/避免合并

Answer 1

如果有人提出异议，这里真的是通用代码：

def merge(self, request, queryset):
    main = queryset[0]
    tail = queryset[1:]

    related = main._meta.get_all_related_objects()

    valnames = dict()
    for r in related:
        valnames.setdefault(r.model, []).append(r.field.name)

    for place in tail:
        for model, field_names in valnames.iteritems():
            for field_name in field_names:
                model.objects.filter(**{field_name: place}).update(**{field_name: main})

        place.delete()

    self.message_user(request, "%s is merged with other places, now you can give it a canonical name." % main)

Answer 2

根据接受的答案中的评论中提供的片段，我能够开发以下内容。此代码不处理GenericForeignKeys。我不认为它们的用途，因为我认为它表明您使用的模型存在问题。

我在这个答案中列出了很多代码来执行此操作，但我已经更新了我的代码以使用提到的here的django-super-deduper。当时，django-super-deduper并没有很好地处理非托管模型。我提交了一个问题，看起来很快就会得到纠正。我也使用django-audit-log，我不想合并这些记录。我保留了签名和@transaction.atomic()装饰器。这在发生问题时很有用。

from django.db import transaction
from django.db.models import Model, Field
from django_super_deduper.merge import MergedModelInstance


class MyMergedModelInstance(MergedModelInstance):
    """
        Custom way to handle Issue #11: Ignore models with managed = False
        Also, ignore auditlog models.
    """
    def _handle_o2m_related_field(self, related_field: Field, alias_object: Model):
        if not alias_object._meta.managed and "auditlog" not in alias_object._meta.model_name:
            return super()._handle_o2m_related_field(related_field, alias_object)

    def _handle_m2m_related_field(self, related_field: Field, alias_object: Model):
        if not alias_object._meta.managed and "auditlog" not in alias_object._meta.model_name:
            return super()._handle_m2m_related_field(related_field, alias_object)

    def _handle_o2o_related_field(self, related_field: Field, alias_object: Model):
        if not alias_object._meta.managed and "auditlog" not in alias_object._meta.model_name:
            return super()._handle_o2o_related_field(related_field, alias_object)


@transaction.atomic()
def merge(primary_object, alias_objects):
    if not isinstance(alias_objects, list):
        alias_objects = [alias_objects]
    MyMergedModelInstance.create(primary_object, alias_objects)
    return primary_object

Answer 3

现在存在两个库，其中包含最新的模型合并功能，其中包含相关模型：

Django Extensions'merge_model_instances管理命令。

Django Super Deduper

Answer 4

在Django 1.10上测试过。希望它可以服务。

def merge(primary_object, alias_objects, model):
"""Merge 2 or more objects from the same django model
The alias objects will be deleted and all the references 
towards them will be replaced by references toward the 
primary object
"""
if not isinstance(alias_objects, list):
    alias_objects = [alias_objects]

if not isinstance(primary_object, model):
    raise TypeError('Only %s instances can be merged' % model)

for alias_object in alias_objects:
    if not isinstance(alias_object, model):
        raise TypeError('Only %s instances can be merged' % model)

for alias_object in alias_objects:
    # Get all the related Models and the corresponding field_name
    related_models = [(o.related_model, o.field.name) for o in alias_object._meta.related_objects]
    for (related_model, field_name) in related_models:
        relType = related_model._meta.get_field(field_name).get_internal_type()
        if relType == "ForeignKey":
            qs = related_model.objects.filter(**{ field_name: alias_object })
            for obj in qs:
                setattr(obj, field_name, primary_object)
                obj.save()
        elif relType == "ManyToManyField":
            qs = related_model.objects.filter(**{ field_name: alias_object })
            for obj in qs:
                mtmRel = getattr(obj, field_name)
                mtmRel.remove(alias_object)
                mtmRel.add(primary_object)
    alias_object.delete()
return True

Answer 5

我一直在寻找一种在Django Admin中合并记录的解决方案，并找到了一个正在这样做的包（https://github.com/saxix/django-adminactions）。

使用方法：

安装包： pip install django-adminactions

将adminactions添加到您的INSTALLED_APPS：

INSTALLED_APPS = (
    'adminactions',
    'django.contrib.admin',
    'django.contrib.messages',
)

向admin.py添加操作：

from django.contrib.admin import site
import adminactions.actions as actions

actions.add_to_site(site)

将服务网址添加到您的urls.py: url(r'^adminactions/', include('adminactions.urls')),

刚才尝试过，它适合我。

Django：合并对象

5 个答案: