How to update fields in a model without creating a new record in django

Question

I have a model in django that I want to update only  that is  when I call it and set the data  it will not create a new record  only update the existing one  How can I do this  Here is what I have   class TemperatureData models Model          date   models DateTimeField          value   models PositiveIntegerField          alert   models BooleanField

User · Accepted Answer

If you get a model instance from the database, then calling the save method will always update that instance. For example:

t = TemperatureData.objects.get(id=1)
t.value = 999  # change field
t.save() # this will update only

If your goal is prevent any INSERTs, then you can override the save method, test if the primary key exists and raise an exception. See the following for more detail:

How Django knows to UPDATE vs. INSERT

User · Answer

You should do it this way ideally  t   TemperatureData objects get id 1  t value   999 t save   value      This allow you to specify which column should be saved and rest are left as they currently are in database   https   code djangoproject com ticket 4102

User · Answer

In my scenario  I want to update the status of status based on his id  student obj   StudentStatus objects get student id 101  student obj status   Enrolled  student obj save     Or If you want the last id from Student Info table you can use the following   student obj   StudentStatus objects get student id StudentInfo objects last   id  student obj status   Enrolled  student obj save

User · Answer

Sometimes it may be required to execute the update atomically that is using one update request to the database without reading it first  Also get-set attribute-save may cause problems if such updates may be done concurrently or if you need to set the new value based on the old field value  In such cases query expressions together with update may by useful  TemperatureData objects filter id 1  update value F  value     1

User · Answer

Django has some documentation about that on their website  see  Saving changes to objects  To summarize         to save changes to an object that s already in the database  use save

[django] How to update fields in a model without creating a new record in django?

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