CODEWITHSUNDEEP
pythonpython-3.xdjango
glumish
glumish

Reputation: 13

Why django ORM .filter() two way binding my data?

Let's say I store my query result temporarily to a variable

temp_doc = Document.objects.filter(detail=res)

and then I want to insert some data in said model and will be something like this

p = Document(detail=res)
p.save()

note that res are object from other model to make some FK relation.

For some reason the temp_doc will contain the new data.

Are .filter() supposed to work like that?
Because with .get() the data inside temp_doc don't change

Upvotes: 1

Views: 64

Answers (1)

iklinac
iklinac

Reputation: 15728

Django Querysets are lazy, this behavior is well documented

QuerySets are lazy – the act of creating a QuerySet doesn’t involve any database activity. You can stack filters together all day long, and Django won’t actually run the query until the QuerySet is evaluated.

So basically that means until you don't ask for data evaluation, database query won't be executed

In your example

temp_doc = Document.objects.filter(detail=res)
p = Document(detail=res)
p.save()
enter code here

evaluating temp_doc now would include newly created Document as database query would return it

simply constructing list would evaluate QuerySet at the start

#evaluation happens here
list(temp_doc) = Document.objects.filter(detail=res)

p = Document(detail=res)
p.save()

Upvotes: 1

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