[FIXED] How can I use a variable in the field of m2m?

Issue

First I am extracting the model name of the M2M field from the value I get through the loop. Then I am trying to add data to m2m table, but this AttributeError: 'ProductAttributes' object has no attribute 'm2m_model' is coming.

attribute  = ProductAttributes.objects.get(pk=pk)
for key in common_keys:
    if initial[key] != new_data[key]:
        # Getting m2m model in lower case
        m2m_model = apps.get_model(app_label=app, model_name=key)._meta.model_name
        attribute.m2m_model.add(new_data[key])

Here's the problem attribute.m2m_model.add(new_data[key]) If I directly name the field then it works fine like below: attribute.color.add(new_data[key]) attribute.ram.add(new_data[key]) I want to make it dynamic.

Here is my model:

class ProductAttributes(models.Model):   
    color               = models.ManyToManyField('Color')
    band_color          = models.ManyToManyField('BandColor')
    ram                 = models.ManyToManyField('RAM')
    vram                = models.ManyToManyField('VRAM')

Thanks in advance, any help would be much appreciated.

Solution

You can work with getattr(…) ^[Python-doc], but it looks like bad code design to rely that the field is the model name in lowercase:

attribute = ProductAttributes.objects.get(pk=pk)
m2m_model = apps.get_model(app_label=app, model_name=key)._meta.model_name
for key in common_keys:
    if initial[key] != new_data[key]:
        # Getting m2m model in lower case
        getattr(attribute, m2m_model).add(new_data[key])

Answered By - willeM_ Van Onsem