Problem with ForeignKey, Django migrations - django

Question

When I tried to migrate my project to a different version I faced this error:
ProgrammingError: ERROR: the id column specified in the foreign key constraint does not exist.
UPDATE: This is the full log: The above exception was the direct cause of the following exception:
Traceback (most recent call last):
File "manage.py", line 23, in <module>
execute_from_command_line(sys.argv)
File "/home/user/MyProjects/forest-venv/lib/python3.5/site-packages/django/core/management/__init__.py", line 371, in execute_from_command_line
utility.execute()
File "/home/user/MyProjects/forest-venv/lib/python3.5/site-packages/django/core/management/__init__.py", line 365, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "/home/user/MyProjects/forest-venv/lib/python3.5/site-packages/django/core/management/base.py", line 288, in run_from_argv
self.execute(*args, **cmd_options)
File "/home/user/MyProjects/forest-venv/lib/python3.5/site-packages/django/core/management/base.py", line 335, in execute
output = self.handle(*args, **options)
File "/home/user/MyProjects/forest-venv/lib/python3.5/site-packages/django/core/management/commands/migrate.py", line 200, in handle
fake_initial=fake_initial,
File "/home/user/MyProjects/forest-venv/lib/python3.5/site-packages/django/db/migrations/executor.py", line 117, in migrate
state = self._migrate_all_forwards(state, plan, full_plan, fake=fake, fake_initial=fake_initial)
File "/home/user/MyProjects/forest-venv/lib/python3.5/site-packages/django/db/migrations/executor.py", line 147, in _migrate_all_forwards
state = self.apply_migration(state, migration, fake=fake, fake_initial=fake_initial)
File "/home/user/MyProjects/forest-venv/lib/python3.5/site-packages/django/db/migrations/executor.py", line 244, in apply_migration
state = migration.apply(state, schema_editor)
File "/home/user/MyProjects/forest-venv/lib/python3.5/site-packages/django/db/migrations/migration.py", line 122, in apply
operation.database_forwards(self.app_label, schema_editor, old_state, project_state)
File "/home/user/MyProjects/forest-venv/lib/python3.5/site-packages/django/db/migrations/operations/fields.py", line 216, in database_forwards
schema_editor.alter_field(from_model, from_field, to_field)
File "/home/user/MyProjects/forest-venv/lib/python3.5/site-packages/django/db/backends/base/schema.py", line 525, in alter_field
old_db_params, new_db_params, strict)
File "/home/user/MyProjects/forest-venv/lib/python3.5/site-packages/django/db/backends/postgresql/schema.py", line 122, in _alter_field
new_db_params, strict,
File "/home/user/MyProjects/forest-venv/lib/python3.5/site-packages/django/db/backends/base/schema.py", line 750, in _alter_field
self.execute(self._create_fk_sql(model, new_field, "_fk_%(to_table)s_%(to_column)s"))
File "/home/user/MyProjects/forest-venv/lib/python3.5/site-packages/django/db/backends/base/schema.py", line 133, in execute
cursor.execute(sql, params)
File "/home/user/MyProjects/forest-venv/lib/python3.5/site-packages/django/db/backends/utils.py", line 100, in execute
return super().execute(sql, params)
File "/home/user/MyProjects/forest-venv/lib/python3.5/site-packages/django/db/backends/utils.py", line 68, in execute
return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)
File "/home/user/MyProjects/forest-venv/lib/python3.5/site-packages/django/db/backends/utils.py", line 77, in _execute_with_wrappers
return executor(sql, params, many, context)
File "/home/user/MyProjects/forest-venv/lib/python3.5/site-packages/django/db/backends/utils.py", line 85, in _execute
return self.cursor.execute(sql, params)
File "/home/user/MyProjects/forest-venv/lib/python3.5/site-packages/django/db/utils.py", line 89, in __exit__
raise dj_exc_value.with_traceback(traceback) from exc_value
File "/home/user/MyProjects/forest-venv/lib/python3.5/site-packages/django/db/backends/utils.py", line 85, in _execute
return self.cursor.execute(sql, params)
But I don't have an id column in my model:
from django.db import models
from django.utils.translation import ugettext_lazy as _
from renter.models import RefAbstract, Renter
from django.contrib.gis.db import models
from textwrap import shorten
class Unitt(RefAbstract):
....//some classes
class Task(RefAbstract):
class Meta(RefAbstract.Meta):
verbose_name = 'task'
verbose_name_plural = 'tasks'
class Spatial(models.Model):
codeq = models.IntegerField('no',help_text='no')
code = models.PositiveIntegerField('cutare',primary_key=True,help_text='cutare')//unique column
codeV = models.IntegerField('novi',help_text='novi')
renter = models.ForeignKey(Renter, on_delete=models.DO_NOTHING, verbose_name='renter')
geometry = models.MultiPolygonField(geography=True, verbose_name='geometry')
class Meta:
verbose_name = 'cutarea'
verbose_name_plural = 'cutarea'
class LScharacteristic(models.Model):
codels = models.ForeignKey(Spatial, on_delete=models.DO_NOTHING, verbose_name = 'cutarea')// Foreign Key
tract = models.CharField('tract',max_length = 80, help_text='tract')
task = models.ForeignKey(Task, on_delete=models.DO_NOTHING, verbose_name='task')
totalarea = models.PositiveIntegerField('totarea',help_text = 'totarea')
explarea = models.PositiveIntegerField('exarea',help_text = 'exarea')
protecttype = models.CharField('category',max_length = 50, help_text = 'category')
class Meta:
verbose_name = 'characteristic'
verbose_name_plural = 'characteristics'
class PlannedUsing(models.Model):
codels = models.ForeignKey(Spatial, on_delete=models.DO_NOTHING, verbose_name = 'cutarea') // Foreign Key
codeq = models.IntegerField(help_text='number')
cutareaShape = models.ForeignKey(CutareaShape, on_delete=models.DO_NOTHING, verbose_name='form')
cuttype = models.ForeignKey(CutareaType, on_delete=models.DO_NOTHING, verbose_name='type1')
managetype = models.ForeignKey(ManageType, on_delete=models.DO_NOTHING, verbose_name='type2')
unit = models.ForeignKey(Unitt, on_delete=models.DO_NOTHING, verbose_name='unit')
composition = models.ForeignKey(Composition, on_delete=models.DO_NOTHING, verbose_name='sort')
assortment = models.ForeignKey(Assortment, on_delete=models.DO_NOTHING, verbose_name='assort')
class Meta:
verbose_name = 'planus'
verbose_name_plural = 'planuss'
What is the id column and why does it exist if I never defined it?
How I can to fix this?

Answer 1

I think that the problem is that your ForeignKey fields do not point explicitly to the field that you have marked as primary (Spatial.code).
By marking Spatial.code as primary you prevent Django from creating the id field. See the documentation But if you point a ForeignKey to just a model it will try to link to the id field of that model.
To fix this you can add to your ForeignKey field the parameter: to_field='code' and add unique=True to Spatial.code.See documentation

Answer 2

You can use
def __str__(self):
return self.etat
or
def __int__(self):
For specif what do you return on your django model.
like this:
tests= models.CharField(max_length=100, verbose_name="Test")
class Meta:
verbose_name = "Tests"
ordering = ['tests']
def __str__(self):
return self.tests