How to bulk update with Django

Question

I d like to update a table with Django - something like this in raw SQL   update tbl name set name    foo  where name    bar    My first result is something like this - but that s nasty  isn t it   list   ModelClass objects filter name    bar   for obj in list      obj name    foo      obj save     Is there a more elegant way

User · Answer

Django 2 2 version now has a bulk update method  release notes    https   docs djangoproject com en stable ref models querysets  bulk-update  Example     get a pk  record dictionary of existing records updates   YourModel objects filter      in bulk          do something with the updates dict      if hasattr YourModel objects   bulk update   and updates        Use the new method     YourModel objects bulk update updates values     list the fields to update   batch size 100  else        The old  amp  slow way     with transaction atomic            for obj in updates values                obj save update fields  list the fields to update

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Update   Django 2 2 version now has a bulk update   Old answer   Refer to the following django documentation section     Updating multiple objects at once   In short you should be able to use    ModelClass objects filter name  bar   update name  foo     You can also use F objects to do things like incrementing rows   from django db models import F Entry objects all   update n pingbacks F  n pingbacks     1    See the documentation   However  note that     This won t use ModelClass save method  so if you have some logic inside it won t be triggered    No django signals will be emitted  You can t perform an  update   on a sliced QuerySet  it must be on an original QuerySet so you ll need to lean on the  filter   and  exclude   methods

User · Answer

Consider using django-bulk-update found here on GitHub   Install  pip install django-bulk-update  Implement   code taken directly from projects ReadMe file   from bulk update helper import bulk update  random names     Walter    The Dude    Donny    Jesus   people   Person objects all    for person in people      r   random randrange 4      person name   random names r   bulk update people     updates all columns using the default db   Update  As Marc points out in the comments this is not suitable for updating thousands of rows at once  Though it is suitable for smaller batches 10 s to 100 s  The size of the batch that is right for you depends on your CPU and query complexity  This tool is more like a wheel barrow than a dump truck

User · Answer

IT returns number of objects are updated in table   update counts   ModelClass objects filter name  bar   update name  quot foo quot    You can refer this link to get more information on bulk update and create  Bulk update and Create

User · Answer

If you want to set the same value on a collection of rows  you can use the update   method combined with any query term to update all rows in one query   some list   ModelClass objects filter some condition  values  id   ModelClass objects filter pk  in some list  update foo bar    If you want to update a collection of rows with different values depending on some condition  you can in best case batch the updates according to values  Let s say you have 1000 rows where you want to set a column to one of X values  then you could prepare the batches beforehand and then only run X update-queries  each essentially having the form of the first example above    the initial SELECT-query    If every row requires a unique value there is no way to avoid one query per update  Perhaps look into other architectures like CQRS Event sourcing if you need performance in this latter case

[django] How to 'bulk update' with Django?

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