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在Django中复制模型实例及其相关对象/用于可复制对象的算法

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在Django中复制模型实例及其相关对象/用于可复制对象的算法

由于删除了CollectedObjects,因此它在Django 1.3中不再起作用。参见变更集14507

我在Django片段上发布了我的解决方案。它很大程度上取决于

django.db.models.query.CollectedObject
用于删除对象的代码:

from django.db.models.query import CollectedObjectsfrom django.db.models.fields.related import ForeignKeydef duplicate(obj, value, field):    """    Duplicate all related objects of `obj` setting    `field` to `value`. If one of the duplicate    objects has an FK to another duplicate object    update that as well. Return the duplicate copy    of `obj`.      """    collected_objs = CollectedObjects()    obj._collect_sub_objects(collected_objs)    related_models = collected_objs.keys()    root_obj = None    # Traverse the related models in reverse deletion order.        for model in reversed(related_models):        # Find all FKs on `model` that point to a `related_model`.        fks = []        for f in model._meta.fields: if isinstance(f, ForeignKey) and f.rel.to in related_models:     fks.append(f)        # Replace each `sub_obj` with a duplicate.        sub_obj = collected_objs[model]        for pk_val, obj in sub_obj.iteritems(): for fk in fks:     fk_value = getattr(obj, "%s_id" % fk.name)     # If this FK has been duplicated then point to the duplicate.     if fk_value in collected_objs[fk.rel.to]:         dupe_obj = collected_objs[fk.rel.to][fk_value]         setattr(obj, fk.name, dupe_obj) # Duplicate the object and save it. obj.id = None setattr(obj, field, value) obj.save() if root_obj is None:     root_obj = obj    return root_obj


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