How do I clone a Django model instance object and save it to the database

Question

Foo objects get pk  foo    lt Foo  test gt    In the database  I want to add another object which is a copy of the object above   Suppose my table has one row  I want to insert the first row object into another row with a different primary key  How can I do that

User · Answer

How to do this was added to the official Django docs in Django1.4

https://docs.djangoproject.com/en/1.10/topics/db/queries/#copying-model-instances

The official answer is similar to miah's answer, but the docs point out some difficulties with inheritance and related objects, so you should probably make sure you read the docs.

User · Answer

Use the below code    from django forms import model to dict  instance   Some objects get slug  something    kwargs   model to dict instance  exclude   id    new instance   Some objects create   kwargs

User · Answer

This does an in-memory copy that you can mutate independently  original   CheckoutItem title  quot test quot        copy   CheckoutItem    for f in CheckoutItem  meta fields     setattr copy  f attname  getattr original  f attname    Or  as a method       def clone self            quot  quot  quot Returns a clone of this instance  quot  quot  quot           clone   self   class             for f in self   class    meta fields              setattr clone  f attname  getattr self  f attname            return clone

User · Answer

There is a package that can do this which creates a UI within the django admin site  https   github com RealGeeks django-modelclone pip install django-modelclone  Add  quot modelclone quot  to INSTALLED APPS and import it within admin py  Then  whenever you want to make a model clonable  you just replace  quot admin ModelAdmin quot  in the given admin model class  quot modelclone ClonableModelAdmin quot   This results in a  quot Duplicate quot  button appearing within the instance details page for that given model

User · Answer

This is yet another way of cloning the model instance   d   Foo objects filter pk 1  values   first      d update   id   None   duplicate   Foo objects create   d

User · Answer

The Django documentation for database queries includes a section on copying model instances   Assuming your primary keys are autogenerated  you get the object you want to copy  set the primary key to None  and save the object again   blog   Blog name  My blog   tagline  Blogging is easy   blog save     blog pk    1  blog pk   None blog save     blog pk    2   In this snippet  the first save   creates the original object  and the second save   creates the copy   If you keep reading the documentation  there are also examples on how to handle two more complex cases   1  copying an object which is an instance of a model subclass  and  2  also copying related objects  including objects in many-to-many relations     Note on miah s answer  Setting the pk to None is mentioned in miah s answer  although it s not presented front and center  So my answer mainly serves to emphasize that method as the Django-recommended way to do it   Historical note  This wasn t explained in the Django docs until version 1 4  It has been possible since before 1 4  though   Possible future functionality  The aforementioned docs change was made in this ticket  On the ticket s comment thread  there was also some discussion on adding a built-in copy function for model classes  but as far as I know they decided not to tackle that problem yet   So this  manual  way of copying will probably have to do for now

User · Answer

Be careful here   This can be extremely expensive if you re in a loop of some kind and you re retrieving objects one by one   If you don t want the call to the database  just do   from copy import deepcopy  new instance   deepcopy object you want copied  new instance id   None new instance save     It does the same thing as some of these other answers  but it doesn t make the database call to retrieve an object   This is also useful if you want to make a copy of an object that doesn t exist yet in the database

User · Answer

There s a clone snippet here  which you can add to your model which does this   def clone self     new kwargs   dict   fld name  getattr old  fld name   for fld in old  meta fields if fld name    old  meta pk      return self   class   objects create   new kwargs

User · Answer

Just change the primary key of your object and run save     obj   Foo objects get pk  lt some existing pk gt   obj pk   None obj save     If you want auto-generated key  set the new key to None   More on UPDATE INSERT here   Official docs on copying model instances  https   docs djangoproject com en 2 2 topics db queries  copying-model-instances

User · Answer

To clone a model with multiple inheritance levels  i e     2  or ModelC below  class ModelA models Model       info1   models CharField max length 64   class ModelB ModelA       info2   models CharField max length 64   class ModelC ModelB       info3   models CharField max length 64    Please refer the question here

User · Answer

I ve run into a couple gotchas with the accepted answer  Here is my solution   import copy  def clone instance       cloned   copy copy instance    don t alter original instance     cloned pk   None     try          delattr cloned    prefetched objects cache       except AttributeError          pass     return cloned   Note  this uses solutions that aren t officially sanctioned in the Django docs  and they may cease to work in future versions  I tested this in 1 9 13   The first improvement is that it allows you to continue using the original instance  by using copy copy  Even if you don t intend to reuse the instance  it can be safer to do this step if the instance you re cloning was passed as an argument to a function  If not  the caller will unexpectedly have a different instance when the function returns   copy copy seems to produce a shallow copy of a Django model instance in the desired way  This is one of the things I did not find documented  but it works by pickling and unpickling  so it s probably well-supported   Secondly  the approved answer will leave any prefetched results attached to the new instance  Those results shouldn t be associated with the new instance  unless you explicitly copy the to-many relationships  If you traverse the the prefetched relationships  you will get results that don t match the database  Breaking working code when you add a prefetch can be a nasty surprise   Deleting  prefetched objects cache is a quick-and-dirty way to strip away all prefetches  Subsequent to-many accesses work as if there never was a prefetch  Using an undocumented property that begins with an underscore is probably asking for compatibility trouble  but it works for now

User · Answer

If you have a OneToOneField then you should do it this way      tmp   Foo objects get pk 1      tmp pk   None     tmp id   None     instance   tmp

User · Answer

Try this  original object   Foo objects get pk  foo   v   vars original object  v pop  pk   new object   Foo   v  new object save

User · Answer

setting pk to None is better  sinse Django can correctly create a pk for you  object copy   MyObject objects get pk      object copy pk   None object copy save

[python] How do I clone a Django model instance object and save it to the database?

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