Re: Django Migration gives an error with OneToOneField

[maninder singh Kumar]

Here's something else I found, the second time around I run django
migrations, the model does get created in the mysql db.  Once it has popped
in the error I guess it has already created a database table with the
unique field constraint.
However I then have to fake initial to get the django_migrations to tick
the migration as done.

regards


[image: --]

Maninder Kumar
[image: http://]about.me/maninder.s.kumar





On Mon, Feb 24, 2020 at 12:20 AM Integr@te System 
wrote:

> Hi,
>
> Would u consider any relative details with result!?
>
> Or try some cmd to more status:
> https://docs.djangoproject.com/en/2.2/topics/migrations/
>
> On Mon, Feb 24, 2020, 00:43 maninder singh Kumar <
> maninder.s.ku...@gmail.com> wrote:
>
>> I am working on an application with two databases and two different
>> dbRouters.  On migrating a model with a OneToOneField I get the following
>> error :
>>
>> django.db.utils.OperationalError: (1824, "Failed to open the referenced
>> table 'auth_user'")
>>
>>
>> The auth dbRouter is for the [auth, sessions, contenttypes, admin] apps
>> while the Redford dbRouter is for the main app.
>>
>> Below is the code for the routers :
>>
>>
>> *auth dbRouter*
>>
>>
>> class AuthRouter:
>> """
>> A router to control all database operations on models in the
>> auth and contenttypes applications.
>> """
>> route_app_labels = ('auth', 'contenttypes', 'sessions', 'admin')
>>
>> def db_for_read(self, model, **hints):
>> """
>> Attempts to read auth and contenttypes models go to auth_db.
>> """
>> if model._meta.app_label in self.route_app_labels:
>> return "default"
>> return False
>>
>> def db_for_write(self, model, **hints):
>> """
>> Attempts to write auth and contenttypes models go to auth_db.
>> """
>> if model._meta.app_label in self.route_app_labels:
>> return "default"
>> return False
>>
>> def allow_relation(self, obj1, obj2, **hints):
>> """
>> Allow relations if a model in the auth or contenttypes apps is
>> involved.
>> """
>>
>> if (obj1._meta.app_label in self.route_app_labels or
>> obj2._meta.app_label == 'julia' or 'redford'
>> ):
>> return True
>> return None
>>
>> def allow_migrate(self, db, app_label, model_name=None, **hints):
>> """
>> Make sure the auth and contenttypes apps only appear in the
>> 'auth_db' database.
>> """
>>
>>
>> if db == 'default':
>> # Migrate Django core app models if current database is home
>> if app_label in ('auth','admin','sessions','contenttypes'):
>> return True
>>
>> else:
>> return False
>>
>> # Non Django core app models should not be migrated if
>> database is home
>> # Other database should not migrate Django core app models
>>
>>
>> elif app_label in ['auth','admin','sessions','contenttypes']:
>> return False
>> # Otherwise no opinion, defer to other routers or default database
>> return None
>>
>>
>>
>> *Redford dbRouter*
>>
>>
>> class RedfordRouter(object):
>>
>> route_app_labels = ('auth', 'contenttypes', 'sessions', 'admin')
>>
>> def db_for_read(self, model, **hints):
>> if model._meta.app_label == 'redford':
>>   return 'redford_db'
>> return False
>>
>> def db_for_write(self, model, **hints):
>> if model._meta.app_label == 'redford':
>>   return 'redford_db'
>> return False
>>
>> def allow_relation(self, obj1, obj2, **hints):
>> if obj1._meta.app_label == 'redford' or obj2._meta.app_label ==
>> 'auth':
>> return True
>> return None
>>
>> def allow_migrate(self, db, app_label, model_name=None, **hints):
>>
>> if db == 'default' or app_label in self.route_app_labels:
>> print(db, app_label)
>> return None
>> elif db == 'redford_db':
>> if app_label == 'redford':
>> return True
>> return False
>> return None
>>
>>
>> The code for the models is as below :
>>
>>
>> class Employer(models.Model):
>>  emp_Name = models.OneToOneField(User, on_delete=models.CASCADE,
>>  null=True)
>>  emp_Company = models.CharField(max_length=100)
>>  emp_Address = models.CharField(max_length=500)
>>  emp_Tel = models.CharField(max_length=100)
>>  emp_JobTitle = models.CharField(max_length=200, null=True)
>>  emp_JobDesc = models.CharField(max_length=600, null=False)
>>
>>  def __str__(self):
>>  return self.emp_Name
>>
>>
>> Hope we can work it out
>>
>>
>> regards
>>
>>
>> [image: --]
>>
>> Maninder Kumar
>> [image: http://]about.me/maninder.s.kumar
>> 
>>
>>
>>

Re: Django Migration gives an error with OneToOneField

[Integr@te System]

Hi,

Would u consider any relative details with result!?

Or try some cmd to more status:
https://docs.djangoproject.com/en/2.2/topics/migrations/

On Mon, Feb 24, 2020, 00:43 maninder singh Kumar 
wrote:

> I am working on an application with two databases and two different
> dbRouters.  On migrating a model with a OneToOneField I get the following
> error :
>
> django.db.utils.OperationalError: (1824, "Failed to open the referenced
> table 'auth_user'")
>
>
> The auth dbRouter is for the [auth, sessions, contenttypes, admin] apps
> while the Redford dbRouter is for the main app.
>
> Below is the code for the routers :
>
>
> *auth dbRouter*
>
>
> class AuthRouter:
> """
> A router to control all database operations on models in the
> auth and contenttypes applications.
> """
> route_app_labels = ('auth', 'contenttypes', 'sessions', 'admin')
>
> def db_for_read(self, model, **hints):
> """
> Attempts to read auth and contenttypes models go to auth_db.
> """
> if model._meta.app_label in self.route_app_labels:
> return "default"
> return False
>
> def db_for_write(self, model, **hints):
> """
> Attempts to write auth and contenttypes models go to auth_db.
> """
> if model._meta.app_label in self.route_app_labels:
> return "default"
> return False
>
> def allow_relation(self, obj1, obj2, **hints):
> """
> Allow relations if a model in the auth or contenttypes apps is
> involved.
> """
>
> if (obj1._meta.app_label in self.route_app_labels or
> obj2._meta.app_label == 'julia' or 'redford'
> ):
> return True
> return None
>
> def allow_migrate(self, db, app_label, model_name=None, **hints):
> """
> Make sure the auth and contenttypes apps only appear in the
> 'auth_db' database.
> """
>
>
> if db == 'default':
> # Migrate Django core app models if current database is home
> if app_label in ('auth','admin','sessions','contenttypes'):
> return True
>
> else:
> return False
>
> # Non Django core app models should not be migrated if
> database is home
> # Other database should not migrate Django core app models
>
>
> elif app_label in ['auth','admin','sessions','contenttypes']:
> return False
> # Otherwise no opinion, defer to other routers or default database
> return None
>
>
>
> *Redford dbRouter*
>
>
> class RedfordRouter(object):
>
> route_app_labels = ('auth', 'contenttypes', 'sessions', 'admin')
>
> def db_for_read(self, model, **hints):
> if model._meta.app_label == 'redford':
>   return 'redford_db'
> return False
>
> def db_for_write(self, model, **hints):
> if model._meta.app_label == 'redford':
>   return 'redford_db'
> return False
>
> def allow_relation(self, obj1, obj2, **hints):
> if obj1._meta.app_label == 'redford' or obj2._meta.app_label ==
> 'auth':
> return True
> return None
>
> def allow_migrate(self, db, app_label, model_name=None, **hints):
>
> if db == 'default' or app_label in self.route_app_labels:
> print(db, app_label)
> return None
> elif db == 'redford_db':
> if app_label == 'redford':
> return True
> return False
> return None
>
>
> The code for the models is as below :
>
>
> class Employer(models.Model):
>  emp_Name = models.OneToOneField(User, on_delete=models.CASCADE,
>  null=True)
>  emp_Company = models.CharField(max_length=100)
>  emp_Address = models.CharField(max_length=500)
>  emp_Tel = models.CharField(max_length=100)
>  emp_JobTitle = models.CharField(max_length=200, null=True)
>  emp_JobDesc = models.CharField(max_length=600, null=False)
>
>  def __str__(self):
>  return self.emp_Name
>
>
> Hope we can work it out
>
>
> regards
>
>
> [image: --]
>
> Maninder Kumar
> [image: http://]about.me/maninder.s.kumar
> 
>
>
>
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> 
> .
>

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Django Migration gives an error with OneToOneField

[maninder singh Kumar]

I am working on an application with two databases and two different
dbRouters.  On migrating a model with a OneToOneField I get the following
error :

django.db.utils.OperationalError: (1824, "Failed to open the referenced
table 'auth_user'")


The auth dbRouter is for the [auth, sessions, contenttypes, admin] apps
while the Redford dbRouter is for the main app.

Below is the code for the routers :


*auth dbRouter*


class AuthRouter:
"""
A router to control all database operations on models in the
auth and contenttypes applications.
"""
route_app_labels = ('auth', 'contenttypes', 'sessions', 'admin')

def db_for_read(self, model, **hints):
"""
Attempts to read auth and contenttypes models go to auth_db.
"""
if model._meta.app_label in self.route_app_labels:
return "default"
return False

def db_for_write(self, model, **hints):
"""
Attempts to write auth and contenttypes models go to auth_db.
"""
if model._meta.app_label in self.route_app_labels:
return "default"
return False

def allow_relation(self, obj1, obj2, **hints):
"""
Allow relations if a model in the auth or contenttypes apps is
involved.
"""

if (obj1._meta.app_label in self.route_app_labels or
obj2._meta.app_label == 'julia' or 'redford'
):
return True
return None

def allow_migrate(self, db, app_label, model_name=None, **hints):
"""
Make sure the auth and contenttypes apps only appear in the
'auth_db' database.
"""


if db == 'default':
# Migrate Django core app models if current database is home
if app_label in ('auth','admin','sessions','contenttypes'):
return True

else:
return False

# Non Django core app models should not be migrated if
database is home
# Other database should not migrate Django core app models


elif app_label in ['auth','admin','sessions','contenttypes']:
return False
# Otherwise no opinion, defer to other routers or default database
return None



*Redford dbRouter*


class RedfordRouter(object):

route_app_labels = ('auth', 'contenttypes', 'sessions', 'admin')

def db_for_read(self, model, **hints):
if model._meta.app_label == 'redford':
  return 'redford_db'
return False

def db_for_write(self, model, **hints):
if model._meta.app_label == 'redford':
  return 'redford_db'
return False

def allow_relation(self, obj1, obj2, **hints):
if obj1._meta.app_label == 'redford' or obj2._meta.app_label ==
'auth':
return True
return None

def allow_migrate(self, db, app_label, model_name=None, **hints):

if db == 'default' or app_label in self.route_app_labels:
print(db, app_label)
return None
elif db == 'redford_db':
if app_label == 'redford':
return True
return False
return None


The code for the models is as below :


class Employer(models.Model):
 emp_Name = models.OneToOneField(User, on_delete=models.CASCADE,
 null=True)
 emp_Company = models.CharField(max_length=100)
 emp_Address = models.CharField(max_length=500)
 emp_Tel = models.CharField(max_length=100)
 emp_JobTitle = models.CharField(max_length=200, null=True)
 emp_JobDesc = models.CharField(max_length=600, null=False)

 def __str__(self):
 return self.emp_Name


Hope we can work it out


regards


[image: --]

Maninder Kumar
[image: http://]about.me/maninder.s.kumar


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