How to reference model instance fields dynamically

[Chris Pagnutti]

Say I have a model like

class MyModel(models.Model)

   name = models.CharField(max_length=100)

   number = models.IntegerField()

In a script, I want to have something like

fields = {"name":"Joe", "number":5}

And I want to update a MyModel instance using the fields dictionary, something like this

inst = MyModel.objects.get(pk=2)

for k,v in fields.iteritems():

   inst.k = v   # I tried with inst.F(k) = v and inst.eval(k) = v but python doesn't like that either

I hope I'm being clear in what I'm trying to do.  The reason I have to do it this way is that I don't know which model, and therefore fields, I'm dealing with until run-time.

Please ask questions if this isn't clear.

[Brad Pitcher]

You can use python's setattr function to do this:

for k,v in fields.iteritems():
    setattr(inst, k, v)

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[Chris Pagnutti]

Awesome.  Thanks Brad.  Now the question is, what if the attribute is a ManyToManyField.

e.g.

inst.k.add(relatedObject)

How to reference k properly if k is a string containing the name of a ManyToManyField of inst?

[Brad Pitcher]

Use setattr's counterpart, getattr :-)

getattr(inst, k).add(relatedObject)

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[Chris Pagnutti]

Indeed.  Was trying that, but wasn't working on account of me forgetting to save inst first.  It's all good now.  Thanks a mil Brad.  All the best.

On Friday, October 26, 2012 11:37:36 AM UTC-4, Chris Pagnutti wrote: