django save model ForeignKey relation

Question

in my model.py

class Layer(models.Model):
    user = models.IntegerField()
    name = models
    ...

class Point(models.Model):
    layers = models.ForeignKey(Layer)
    meta = models.TextField()
    ...

in my view.py

def datasave(request, id):
    mid = request.POST.get("layerid",default = "")
    metas = request.POST.get("meta",default = "")

    cs = Point()
    cs.layers = mid
    cs.meta = metas
    cs.save()

but it gives an error in my django debug..in my project i use geodjango,openlayers and extjs... i didnt find any solution about saving my post

i didnt make any relation with my foreignkey.. basically i want to make a layer than when i want to add a point in my layer , i want save my point with layer id....

Answer 1

A more efficient way is to specify the foreign key by adding an "_id" at the end, like this:

cs = Point(layers_id = mid, meta = metas)
cs.save()

DO NOT do layers=XXX.objects.get(id=###) because that's doubling the number of database queries.

ALSO ... you're not cleaning your POST data here, which is pretty dangerous. Get it like this:

from django import forms
id_field = forms.IntegerField()
layer_id = id_field.clean(request.POST.get("layerId", "")

Answer 2

It's helpful to post the traceback to help understand your problem (for future questions).

It looks to me like you are passing in a number to your Point instance's layers attribute which would cause a ValueError. The only place you can pass a number to a foreign key field is in a django form which does the lookup for you.

You need to assign an actual Layer instance instead.

cs = Point()
cs.layers = Layer.objects.get(id=mid)
cs.meta = metas
cs.save()