model_to_dict: AttributeError: 'str' object has no attribute '_meta'

Question

I have following error when I run the code. Can any of you please help to me solve the issue?

AttributeError: 'str' object has no attribute '_meta'

---

Traceback (most recent call last):
  File "C:\Users\ipcramk\PycharmProjects\Quality_Check_UI\lib\site-packages\django\core\handlers\exception.py", line 34, in inner
    response = get_response(request)
  File "C:\Users\ipcramk\PycharmProjects\Quality_Check_UI\lib\site-packages\django\core\handlers\base.py", line 115, in _get_response
    response = self.process_exception_by_middleware(e, request)
  File "C:\Users\ipcramk\PycharmProjects\Quality_Check_UI\lib\site-packages\django\core\handlers\base.py", line 113, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "C:\Users\ipcramk\PycharmProjects\Quality_Check_UI\lib\site-packages\django\contrib\auth\decorators.py", line 21, in _wrapped_view
    return view_func(request, *args, **kwargs)
  File "C:\Users\ipcramk\PycharmProjects\Quality_Check_UI\lib\site-packages\django\contrib\auth\decorators.py", line 21, in _wrapped_view
    return view_func(request, *args, **kwargs)
  File "C:\Users\ipcramk\Desktop\Desktop files\pYTHON TRAINING\Django\Quality_Check_UI\QC_project\app1\views.py", line 328, in qc3_approval_view
    cn_data_form = qc3_approval_form( instance=request.GET['key'] )
  File "C:\Users\ipcramk\PycharmProjects\Quality_Check_UI\lib\site-packages\django\forms\models.py", line 292, in __init__
    object_data = model_to_dict(instance, opts.fields, opts.exclude)
  File "C:\Users\ipcramk\PycharmProjects\Quality_Check_UI\lib\site-packages\django\forms\models.py", line 82, in model_to_dict
    opts = instance._meta
AttributeError: 'str' object has no attribute '_meta'
[24/Oct/2021 12:02:40] "GET /cn_entry/approval_page?key=2 HTTP/1.1" 500 92849

---

Views.py

def qc3_approval_view(request):
    cn_data_form = qc3_approval_form( instance=request.GET['key'] )

---

forms.py

class qc3_approval_form(forms.ModelForm ):

    class Meta:
        model = cn_data_tables
        fields = ('status_qc3',)

---

models.py

class cn_data_tables(models.Model):
    sl_no = models.AutoField(primary_key=True)
    cn_number = models.CharField(max_length=10, null=False)
    status_qc3 = models.ForeignKey( 'status_list_table',related_name='status_qc3', on_delete=models.CASCADE, default=3 )


    def __int__(self):
        return self.sl_no

---

Answer 1

I changed views.py as below and it is working.

def qc3_approval_view(request):
    cn_data= cn_data_tables.objects.filter(sl_no=request.GET['key']).first()
    cn_data_form = qc3_approval_form( instance=cn_data)

Answer 2

Your problem is caused because you are not providing an instance to qc3_approval_form , instead, you are providing a string, which does not have the _meta attribute.

Changing the views.py to provide an instance to the form should work.

def qc3_approval_view(request):
    cn_data= cn_data_tables.objects.filter(sl_no=request.GET['key']).first()
    cn_data_form = qc3_approval_form( instance=cn_data)

Answer 3

The argument of the register func is not a str, just write the name of the model. The string has not that attribute, but the function does. so, in the admin.py file write:

admin.site.register(cn_data.tables)

that just happend to me and that worked.