You had the correct approach commented out, why?

https://docs.djangoproject.com/en/1.11/ref/models/querysets/#get-or-create get_or_create returns a tuple of the form (object, created [boolean]).

What you'd want to do is split out the result of that command:

objx, created = GoogleProperty.objects.get_or_create(google_email=current_user)

Then you can do:

if not created:
    objx.view_id = view_id
    objx.save()

get_or_create does not just return the object:

Returns a tuple of (object, created), where object is the retrieved or created object and created is a boolean specifying whether a new object was created.

In your case d has been assigned this tuple instead of the object you expected, so you get the attribute error. You can fix your code by changing it to:

d, created = DiaSemana.objects.get_or_create(dias=diaSemana)

The following two lines look unnecessary to me. The get_or_create call above ensures that d.dias=diaSemana, so there's no need to assign it again. There's probably no need to call save either.

d.dias = diaSemana;
d.save()

You are returning a tuple here:

elif retailer_pk:
    return (request, 'page-retailer-single.html', {
        "products": products,
        "sorting": filt["sorting"],
        "filtering": filt["filtering"],
        "retailer": retailer,
    })

Did you forget to add render there perhaps:

elif retailer_pk:
    return render(request, 'page-retailer-single.html', {
        "products": products,
        "sorting": filt["sorting"],
        "filtering": filt["filtering"],
        "retailer": retailer,
    })

You should provide the full trace back. We aren't mind readers.

This is wrong:

return (request, 'dashboard.html', {'section': 'dashboard'})

You are returning a tuple where you have to return a Response.

Instead of directly returning a response you can use the render-shortcut:

from django.shortcuts import render
from django.contrib.auth.decorators import login_required

@login_required()
def dashboard(request):
    return render(request, 'dashboard.html', {'section': 'dashboard'})

You have a typo - it should be fields, not field:

class UserSerializer(serializers.ModelSerializer):
    class Meta:
        model = User
        fields = ('id', 'facebook_id', 'first_name', 'last_name', 'access_token')
      # HERE ^

In your view args should be dict not tuple:

# args = ()
args = {}

.get_or_create(…) ^[Django-doc] returns a 2-tuple: as first element the item you retrieve or create, and as second a boolean that indicates if it was created or not. You can use iterable unpacking to unpack the object:

insert, __ = CustomerPurchaseOrderDetail.objects.get_or_create(
    profile=client,
    product = v,
    quantity=quantity,
    unitprice=price,
    discounted_amount = discount,
    discounted_unitprice = discount,
)

Calling .save() however does not make much sense, since the .get_or_create(…) will already save the object to the database.

EDIT: You can increase the quantity with:

insert, created = CustomerPurchaseOrderDetail.objects.get_or_create(
    profile=client,
    product = v,
    unitprice=price,
    discounted_amount = discount,
    discounted_unitprice = discount,
    defaults=dict(quantity=quantity)
)

if not created:
    insert.quantity += quantity
    insert.save()