ManyToMany relationship in django models

Question

I'm trying to add relation between three table with manyToMany relationship. I'm learning python and new for Django framework. For requirement, An user can add a project and he also can add permission for view for another user. It means an user can have multiple projects and a project also have multiple user. User model is default user model of django.

and the project model is:

Projects/model.py

from django.db import models
from django.contrib.auth.models import User
# Create your models here.


class Projects(models.Model):
    project_title = models.CharField(max_length=255)
    description = models.TextField(blank=True)
    privacy = models.SmallIntegerField(default=1) # 1 for public, 2 for private
    status = models.SmallIntegerField(default=1) #1 for active, 2 for deactive, 3 for delete, 4 for depricated
    created_at = models.DateTimeField('date published', blank=True, default=False)
    users = models.ManyToManyField(User, through="UserProjects")

class UserProjects(models.Model):
    user = models.ForeignKey(User,blank=True, default=False)
    project = models.ForeignKey(Projects,blank=True)
    owner = models.SmallIntegerField(default=1)

It's not working. When i'm add a project is produce some error..

Traceback (most recent call last):
  File "C:\Users\Jitendra\AppData\Local\Programs\Python\Python35-32\lib\site-pac
kages\django\core\handlers\exception.py", line 41, in inner
    response = get_response(request)
  File "C:\Users\Jitendra\AppData\Local\Programs\Python\Python35-32\lib\site-pac
kages\django\core\handlers\base.py", line 187, in _get_response
    response = self.process_exception_by_middleware(e, request)
  File "C:\Users\Jitendra\AppData\Local\Programs\Python\Python35-32\lib\site-pac
kages\django\core\handlers\base.py", line 185, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "E:\Programs\Python\RestClient\Projects\views.py", line 29, in add
    p.save()
  File "C:\Users\Jitendra\AppData\Local\Programs\Python\Python35-32\lib\site-pac
kages\django\db\models\base.py", line 806, in save
    force_update=force_update, update_fields=update_fields)
  File "C:\Users\Jitendra\AppData\Local\Programs\Python\Python35-32\lib\site-pac
kages\django\db\models\base.py", line 836, in save_base
    updated = self._save_table(raw, cls, force_insert, force_update, using, upda
te_fields)
  File "C:\Users\Jitendra\AppData\Local\Programs\Python\Python35-32\lib\site-pac
kages\django\db\models\base.py", line 922, in _save_table
    result = self._do_insert(cls._base_manager, using, fields, update_pk, raw)
  File "C:\Users\Jitendra\AppData\Local\Programs\Python\Python35-32\lib\site-pac
kages\django\db\models\base.py", line 961, in _do_insert
    using=using, raw=raw)
  File "C:\Users\Jitendra\AppData\Local\Programs\Python\Python35-32\lib\site-pac
kages\django\db\models\manager.py", line 85, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "C:\Users\Jitendra\AppData\Local\Programs\Python\Python35-32\lib\site-pac
kages\django\db\models\query.py", line 1063, in _insert
    return query.get_compiler(using=using).execute_sql(return_id)
  File "C:\Users\Jitendra\AppData\Local\Programs\Python\Python35-32\lib\site-pac
kages\django\db\models\sql\compiler.py", line 1098, in execute_sql
    for sql, params in self.as_sql():
  File "C:\Users\Jitendra\AppData\Local\Programs\Python\Python35-32\lib\site-pac
kages\django\db\models\sql\compiler.py", line 1051, in as_sql
    for obj in self.query.objs
  File "C:\Users\Jitendra\AppData\Local\Programs\Python\Python35-32\lib\site-pac
kages\django\db\models\sql\compiler.py", line 1051, in <listcomp>
    for obj in self.query.objs
  File "C:\Users\Jitendra\AppData\Local\Programs\Python\Python35-32\lib\site-pac
kages\django\db\models\sql\compiler.py", line 1050, in <listcomp>
    [self.prepare_value(field, self.pre_save_val(field, obj)) for field in field
s]
  File "C:\Users\Jitendra\AppData\Local\Programs\Python\Python35-32\lib\site-pac
kages\django\db\models\sql\compiler.py", line 990, in prepare_value
    value = field.get_db_prep_save(value, connection=self.connection)
  File "C:\Users\Jitendra\AppData\Local\Programs\Python\Python35-32\lib\site-pac
kages\django\db\models\fields\__init__.py", line 770, in get_db_prep_save
    prepared=False)
  File "C:\Users\Jitendra\AppData\Local\Programs\Python\Python35-32\lib\site-pac
kages\django\db\models\fields\__init__.py", line 1459, in get_db_prep_value
    value = self.get_prep_value(value)
  File "C:\Users\Jitendra\AppData\Local\Programs\Python\Python35-32\lib\site-pac
kages\django\db\models\fields\__init__.py", line 1438, in get_prep_value
    value = super(DateTimeField, self).get_prep_value(value)
  File "C:\Users\Jitendra\AppData\Local\Programs\Python\Python35-32\lib\site-pac
kages\django\db\models\fields\__init__.py", line 1296, in get_prep_value
    return self.to_python(value)
  File "C:\Users\Jitendra\AppData\Local\Programs\Python\Python35-32\lib\site-pac
kages\django\db\models\fields\__init__.py", line 1399, in to_python
    parsed = parse_datetime(value)
  File "C:\Users\Jitendra\AppData\Local\Programs\Python\Python35-32\lib\site-pac
kages\django\utils\dateparse.py", line 94, in parse_datetime
    match = datetime_re.match(value)
TypeError: expected string or bytes-like object
[28/Jul/2017 22:25:10] "POST /projects/add/ HTTP/1.1" 500 145532

And here the projects/view.py

def add(request):
    form = ProjectForm()
    if request.method == "POST":
        form = ProjectForm(request.POST)
        if form.is_valid():
            p = Projects(project_title=request.POST.get("project_title"), description=request.POST.get("description"),
                         status=1, privacy=1)
            p.save()
            sp = UserProjects(user_id=request.user.id, project_id=p.id)
            sp.save()
            p.users.add(sp)
            messages.success(request, 'Profile details updated.')

    view_data = {
        "form": form,
        'title': "Add new project"
    }
    return render(request, 'projects/add.html', view_data)

I dont know, whats wrong with it. Please guide me. Thanks

Answer 1

From Django docs :

class DateTimeField(**kwargs)

Default widget: DateTimeInput

Empty value: None

Normalizes to: A Python datetime.datetime object.

Validates that the given value is either a datetime.datetime, datetime.date or string formatted in a particular datetime format.

Error message keys: required, invalid

You can read that DateTimeField validates that given value is either datetime.datetime, datetime.date or string formatted in particular datetime format, however you set default=False in your model definitions. So I would guess the problem lays in there.