question : in utils/forms/is_form_persisted what is form.instance._state.adding

[piscvau]

Helllo
thanks a lot for the example.
I do not understant the following code
form.instance._state.adding
Where are the _state.adding attributes defined?
I thank you in advance if you can help.

[philgyford]

form.instance is the instance of the model that's being added.

We can look at the Django source's Model class to find the _state attribute: https://github.com/django/django/blob/main/django/db/models/base.py#L472

class Model(AltersData, metaclass=ModelBase):
    def __init__(self, *args, **kwargs):
        # Alias some things as locals to avoid repeat global lookups
        cls = self.__class__
        opts = self._meta
        _setattr = setattr
        _DEFERRED = DEFERRED
        if opts.abstract:
            raise TypeError("Abstract models cannot be instantiated.")

        pre_init.send(sender=cls, args=args, kwargs=kwargs)

        # Set up the storage for instance state
        self._state = ModelState()

        # ... more here ...

And the ModelState() class is defined just above it: https://github.com/django/django/blob/main/django/db/models/base.py#L447

class ModelState:
    """Store model instance state."""

    db = None
    # If true, uniqueness validation checks will consider this a new, unsaved
    # object. Necessary for correct validation of new instances of objects with
    # explicit (non-auto) PKs. This impacts validation only; it has no effect
    # on the actual save.
    adding = True
    fields_cache = ModelStateFieldsCacheDescriptor()

(I don't pretend to understand these completely, and I don't remember where I learned about using that for this code. As a rule it's not great to use "private" attributes, which usually start with an underscore like _state does.