many-to-many in list display django

    class PurchaseOrder(models.Model):
        product = models.ManyToManyField('Product')
        vendor = models.ForeignKey('VendorProfile')
        dollar_amount = models.FloatField(verbose_name='Price')


    class Product(models.Model):
       products = models.CharField(max_length=256)

       def __unicode__(self):
           return self.products

I have that code. Unfortunately, the error comes in admin.py with the ManyToManyField

    class PurchaseOrderAdmin(admin.ModelAdmin):
        fields = ['product', 'dollar_amount']
        list_display = ('product', 'vendor')

The error says:

'PurchaseOrderAdmin.list_display[0]', 'product' is a ManyToManyField which is not supported.

However, it compiles when I take 'product' out of list_display. So how can I display 'product' in list_display without giving it errors?

edit : Maybe a better question would be how do you display a ManyToManyField in list_display?

You may not be able to do it directly. From the documentation of list_display

ManyToManyField fields aren’t supported, because that would entail executing a separate SQL statement for each row in the table. If you want to do this nonetheless, give your model a custom method, and add that method’s name to list_display. (See below for more on custom methods in list_display.)

You can do something like this:

    class PurchaseOrderAdmin(admin.ModelAdmin):
        fields = ['product', 'dollar_amount']
        list_display = ('get_products', 'vendor')

        def get_products(self, obj):
            return "\n".join([p.products for p in obj.product.all()])

OR define a model method, and use that

    class PurchaseOrder(models.Model):
        product = models.ManyToManyField('Product')
        vendor = models.ForeignKey('VendorProfile')
        dollar_amount = models.FloatField(verbose_name='Price')

        def get_products(self):
            return "\n".join([p.products for p in self.product.all()])

and in the admin list_display

    list_display = ('get_products', 'vendor')

From: stackoverflow.com/q/18108521

Back to homepage or read more recommendations: