from django import VERSION
from django.conf import settings
from django.contrib.contenttypes.fields import GenericForeignKey
from django.contrib.contenttypes.models import ContentType
from django.db import models
from django.utils.translation import ugettext_lazy as _


def get_user_model_fk_ref():
    """Get user model depending on Django version."""
    ver = VERSION

    if ver[0] >= 1 and ver[1] >= 5:
        return settings.AUTH_USER_MODEL
    else:
        return 'auth.User'


class GenericLink(models.Model):
    """
    Relates an object with an url and its data
    """

    content_type = models.ForeignKey(ContentType, on_delete=models.CASCADE)
    object_id = models.PositiveIntegerField(db_index=True)
    content_object = GenericForeignKey()

    url = models.URLField()
    title = models.CharField(max_length=200)
    description = models.TextField(max_length=1000, null=True, blank=True)

    user = models.ForeignKey(get_user_model_fk_ref(), null=True, blank=True,
                             on_delete=models.SET_NULL)
    created_at = models.DateTimeField(auto_now_add=True, db_index=True)

    is_external = models.BooleanField(default=True, db_index=True)

    class Meta:
        ordering = ("-created_at", )
        verbose_name = _("Generic Link")
        verbose_name_plural = _("Generic Links")

    def __unicode__(self):
        return self.url

from django.contrib.auth import get_user_model
from django.contrib.contenttypes.fields import GenericForeignKey
from django.contrib.contenttypes.models import ContentType
from django.db import models
from django.utils.translation import ugettext_lazy as _


class GenericLink(models.Model):
    """
    Relates an object with an url and its data
    """

    content_type = models.ForeignKey(ContentType, on_delete=models.CASCADE)
    object_id = models.PositiveIntegerField(db_index=True)
    content_object = GenericForeignKey()

    url = models.URLField()
    title = models.CharField(max_length=200)
    description = models.TextField(max_length=1000, null=True, blank=True)

    user = models.ForeignKey(get_user_model(), null=True, blank=True,
                             on_delete=models.SET_NULL)
    created_at = models.DateTimeField(auto_now_add=True, db_index=True)

    is_external = models.BooleanField(default=True, db_index=True)

    class Meta:
        ordering = ("-created_at", )
        verbose_name = _("Generic Link")
        verbose_name_plural = _("Generic Links")

    def __unicode__(self):
        return self.url

Make User model compatible with Django 2.x
Make User model compatible with Django 2.x

+ from django.contrib.auth import get_user_model
- from django import VERSION
- from django.conf import settings
  from django.contrib.contenttypes.fields import GenericForeignKey
  from django.contrib.contenttypes.models import ContentType
  from django.db import models
  from django.utils.translation import ugettext_lazy as _
- 
- 
- def get_user_model_fk_ref():
-     """Get user model depending on Django version."""
-     ver = VERSION
- 
-     if ver[0] >= 1 and ver[1] >= 5:
-         return settings.AUTH_USER_MODEL
-     else:
-         return 'auth.User'
  
  
  class GenericLink(models.Model):
      """
      Relates an object with an url and its data
      """
  
      content_type = models.ForeignKey(ContentType, on_delete=models.CASCADE)
      object_id = models.PositiveIntegerField(db_index=True)
      content_object = GenericForeignKey()
  
      url = models.URLField()
      title = models.CharField(max_length=200)
      description = models.TextField(max_length=1000, null=True, blank=True)
  
-     user = models.ForeignKey(get_user_model_fk_ref(), null=True, blank=True,
+     user = models.ForeignKey(get_user_model(), null=True, blank=True,
                               on_delete=models.SET_NULL)
      created_at = models.DateTimeField(auto_now_add=True, db_index=True)
  
      is_external = models.BooleanField(default=True, db_index=True)
  
      class Meta:
          ordering = ("-created_at", )
          verbose_name = _("Generic Link")
          verbose_name_plural = _("Generic Links")
  
      def __unicode__(self):
          return self.url
  
Make User model compatible with Django 2.x
## Code Before:
from django import VERSION
from django.conf import settings
from django.contrib.contenttypes.fields import GenericForeignKey
from django.contrib.contenttypes.models import ContentType
from django.db import models
from django.utils.translation import ugettext_lazy as _


def get_user_model_fk_ref():
    """Get user model depending on Django version."""
    ver = VERSION

    if ver[0] >= 1 and ver[1] >= 5:
        return settings.AUTH_USER_MODEL
    else:
        return 'auth.User'


class GenericLink(models.Model):
    """
    Relates an object with an url and its data
    """

    content_type = models.ForeignKey(ContentType, on_delete=models.CASCADE)
    object_id = models.PositiveIntegerField(db_index=True)
    content_object = GenericForeignKey()

    url = models.URLField()
    title = models.CharField(max_length=200)
    description = models.TextField(max_length=1000, null=True, blank=True)

    user = models.ForeignKey(get_user_model_fk_ref(), null=True, blank=True,
                             on_delete=models.SET_NULL)
    created_at = models.DateTimeField(auto_now_add=True, db_index=True)

    is_external = models.BooleanField(default=True, db_index=True)

    class Meta:
        ordering = ("-created_at", )
        verbose_name = _("Generic Link")
        verbose_name_plural = _("Generic Links")

    def __unicode__(self):
        return self.url

## Instruction:
Make User model compatible with Django 2.x
## Code After:
from django.contrib.auth import get_user_model
from django.contrib.contenttypes.fields import GenericForeignKey
from django.contrib.contenttypes.models import ContentType
from django.db import models
from django.utils.translation import ugettext_lazy as _


class GenericLink(models.Model):
    """
    Relates an object with an url and its data
    """

    content_type = models.ForeignKey(ContentType, on_delete=models.CASCADE)
    object_id = models.PositiveIntegerField(db_index=True)
    content_object = GenericForeignKey()

    url = models.URLField()
    title = models.CharField(max_length=200)
    description = models.TextField(max_length=1000, null=True, blank=True)

    user = models.ForeignKey(get_user_model(), null=True, blank=True,
                             on_delete=models.SET_NULL)
    created_at = models.DateTimeField(auto_now_add=True, db_index=True)

    is_external = models.BooleanField(default=True, db_index=True)

    class Meta:
        ordering = ("-created_at", )
        verbose_name = _("Generic Link")
        verbose_name_plural = _("Generic Links")

    def __unicode__(self):
        return self.url
