Re: Getting hold of an instance of a model from inside RelatedManager

On Tuesday, January 25, 2011 3:34:03 PM UTC, kmpm wrote:

I have some issues with getting hold of the instance of a Model to which a RelatedManager got contributed to.

Is that at all possible and if so, how?

From my_method below I can get hold of the model RelatedStuff by calling self.model but that really doesn't get me there.

class MainStuff(models.Model):

    ....

    

class RelatedStuff(models.Model):

    ...

    main = models.ForeignKey(MainStuff)

    objects = CustomManager()

class CustomManager(models.Manager):

    use_for_related_fields=True

    

    def my_method(self):

        #here I would like to access the instance of MainStuff to which this got contributed

Interesting question. Unfortunately, looking at the code, it doesn't seem like you can. Django creates a new RelatedManager class every time, but it does this via a closure - and the instance is only accessible within the closure.

There are probably good reasons why it's done that way (I suspect passing the instance as a parameter and making it available as an attribute would cause a persistent reference to be kept, which would mean that the instance would never be garbage-collected).

--

DR.

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