I need one help. I have one existing mysql table in my localhost database and I need it to migrate using Django and Python. Here is my code:
settings.py
DATABASES = {
'default': {
'ENGINE': 'django.db.backends.mysql',
'NAME': 'djangotest',
'USER': 'root',
'PASSWORD': '',
'HOST': '',
'PORT': '',
}
}
I am giving my table structure below.
Person:
id name phone age
models.py:
# -*- coding: utf-8 -*-
from __future__ import unicode_literals
from django.db import models
# Create your models here.
class Person(models.Model):
name = models.CharField(max_length=200)
phone = models.CharField(max_length=15)
age = models.IntegerField()
Actually I am new to Django and Python and here I need to know command which can migrate the existing table.
to create migrations you need to use this command -
python manage.py makemigrations
the above command will create a file inside the migrations folder in your app directory and
to create/update table using the migration file in the database
python manage.py migrate
The above command will create/update a table in your DB.
Django Migration Docmentation
Let me know, if this is what you want!
In reference to akhilsp, I did not have to worry about table names using the _ format. Using the inspectdb command returned a Meta data for whatever the current table name is that I used in my model.
class Meta:
managed = False
db_table = 'malware'
Add --fake option to migrate command:
--fake
Tells Django to mark the migrations as having been applied or unapplied, but without actually running the SQL to change your
database schema.
This is intended for advanced users to manipulate the current
migration state directly if they’re manually applying changes; be
warned that using --fake runs the risk of putting the migration state
table into a state where manual recovery will be needed to make
migrations run correctly.
If you just start django project and didn't have initial migration: comment your Person model, make initial migration, apply it, uncomment Person, make migration for Person and at last migrate Person with --fake option.
You can use inspectdb command from the shell.
python manage.py inspectdb
This will print models corresponding to the current database structure. You copy the required model, make changes like adding validations, and then add other models.
python manage.py makemigrations will create migrations, and
python manage.py migrate will apply those migrations.
N.B: Your table name should be in the format "appname_modelname" where appname is name for django app name (not project name).
Related
Why do I get this error: FieldError: Unsupported lookup 'unaccent' for CharField or join on the field not permitted?
Info
Language: Python
Platform: Django
Database: PostgreSQL
Code
View:
def search(request):
query = request.GET.get("query")
searched = Book.objects.filter(title__unaccent__icontains=query) # Error here
return render(request, "main/search.html", {
"query": query,
"searched": searched,
})
Expected output
Unaccent the query and search for the unaccented version in the database.
Description
I get the error FieldError: Unsupported lookup 'unaccent' for CharField or join on the field not permitted when I try to query the database using __unaccent while using the advanced search features mentioned in the django docs.
If unaccent or any other PostgreSQL specific lookup, first
Add django.contrib.postgres to your settings.py INSTALLED_APPS.
Activate the lookup's extension on PostgreSQL. For unaccent, click here (under "Usage"), or you could
Perform the extension's migration operation. For unaccent, the extension is called UnaccentExtension. You can do this migration operation by
$ ./manage.py makemigrations --empty your_app_name
Then head over to the migration file created in the migrations folder of your app. If you're not sure which one is the file that was just created, the newest file is usually the one you created. To be extra careful, look into the terminal output that was displayed after you ran the above command. It is going to include the name of the file under the heading Migrations for your_app_name.
Then, in that file, delete the content and paste this:
from django.contrib.postgres.operations import UnaccentExtension
from django.db import migrations
class Migration(migrations.Migration):
dependencies = [
('<your_app_name>', '<previous_migration_file>'),
]
operations = [
UnaccentExtension()
]
In the above code, replace <your_app_name> with the name of your app, and previous_migration_file with the name of the migration file before this one, not including the .py file extension. To find the previous migration file, look at the number of the migration file you're in (for example, in 0008_auto_20220104_1352, 0008 is the number of the file) and subtract 1 (for example, the previous file of 0008_auto_20220104_1352 is going to start with 0007).
After making the changes, python3 manage.py migrate to migrate your changes. You can now access the unaccent extension.
I used sqlite3 during development, then changed my database settings to postgresql:
DATABASES = {
'default': {
'ENGINE': 'django.db.backends.postgresql_psycopg2',
'NAME': 'test2',
'USER': 'postgres',
'PASSWORD': 'aman',
'HOST': 'localhost',
'PORT': '5432',
}
}
Regardless of any command I write, it gives me the error:
django.db.utils.ProgrammingError: relation "taksist_category" does not exist
LINE 1: ...st_category"."id", "taksist_category"."name" FROM "taksist_c...
Category model exists inside taksist application. If I take back my database settings to sqlite3, then application runs successfully.
I cannot even run my server. Even if there is a problem with my model taksist/Category, my application should run. Here strange thing is whatever command is written, I got this error. I cannot do makemigrations, migrate, runserver.
What did I do to solve the issue:
deleted migrations folder, and tried makemigrations
I created empty migrations folder with init.py inside, and
tried makemigrations
python manage.py migrate --fake
none of above worked.
Here is taksist.category model, in case.
class Category(models.Model):
id = models.AutoField(primary_key=True)
name = models.CharField(max_length = 20)
def __str__(self):
return self.name
Any help of yours is appreciated. thank you in advance.
The root cause for "relation does not exist" is that migrations have not been run.
However, via the comments:
whatever command I execute, I got this error. even runserver, makemigrations and migrate. after change database settings to postgresql, i could not migrate. i can do nothing.
That is likely to mean you've written your application in a way that it accesses the database during initialization time, e.g. something like
from my_app.models import Blog
default_blog = Blog.objects.get(pk=1)
def view(...):
This means Django will attempt to access the database as soon as that module is imported. If that module gets imported while Django is trying to initialize itself for migrate, you get an exception.
You can look at the traceback for your django.db.utils.ProgrammingError to figure out what the offending access is and fix it. For instance, the above pattern would be better served by something like a get_default_blog() function.
If I take back my database settings to sqlite3, then application runs successfully.
This bug also means that if you rename or delete your current, working SQLite database, you can't get a new one going either, since attempting to migrate it would fail with a similar error. This is not just Postgres's "fault" here.
If it' a test DB do a py manage.py flush
command, then run the py manage.py makemigrations again, then the py manage.py migrate command.
That should resolve.
I need to change the relationship of a model field from ForeignKey to ManyToManyField. This comes with a data migration, to update the pre-existing data.
The following is the original model (models.py):
class DealBase(models.Model):
[...]
categoria = models.ForeignKey('Categoria')
[...]
)
I need the model field 'categoria' to establish a many2many relationship with the model 'Categoria' in the app 'deal'.
What I did:
Create a new field 'categoria_tmp' in DealBase
class DealBase(models.Model):
categoria = models.ForeignKey('Categoria')
categoria_tmp = models.ManyToManyField('Categoria',related_name='categoria-temp')
make a schema migration
python manage.py makemigrations
Edit the migrationfile.py to migrate data from categoria to categoria-tmp
def copy_deal_to_dealtmp(apps, schema_editor):
DealBase = apps.get_model('deal', 'DealBase')
for deal in DealBase.objects.all():
deal.categoria_tmp.add(deal.categoria)
deal.save()
class Migration(migrations.Migration):
dependencies = [
('deal', '0017_dealbase_indirizzo'),
]
operations = [
migrations.AddField(
model_name='dealbase',
name='categoria_tmp',
field=models.ManyToManyField(related_name='categoria-temp', to='deal.Categoria'),
preserve_default=True,
),
migrations.RunPython(
copy_deal_to_dealtmp
)
]
make data migration
python manage.py migrate
Finally I need to delete the column 'dealbase.categoria' and rename the column 'dealbase.categoria-tmp' to 'dealbase.categoria'
I'm stuck at step 5.
Could someone help me out? I cannot find online an answer, I'm using Django 1.8.
Thanks!
You just need to create two additional migrations: one to remove the old field and the other to alter the new field.
First remove dealbase.categoria and create a migration and then rename dealbase.categoria-tmp to dealbase.categoria and create another migration.
This will delete the first field and then alter the tmp field to the correct name.
Try this, may help you.
Step 1 as yours
python manage.py makemigrations && python manage.py migrate
Open shell
for i in DealBase.objects.all()
i.categoria_tmp.add(i.categoria)
Remove your field categoria
python manage.py makemigrations && python manage.py migrate
Add field
categoria = models.ManyToManyField('Categoria',related_name='categoria-temp')
Then
python manage.py makemigrations && python manage.py migrate
Open shell
for i in DealBase.objects.all():
for j in i.categoria_tmp.all():
i.categoria.add(j)
Remove field categoria_tmp
python manage.py makemigrations && python manage.py migrate
If you don't have any data in this model, just comment on that model, and then run manage.py makemigrations and migrate. Then delete the wrong field and delete the comment code, and make makemigrations and migrate. This also works in Django 2.
I have two users, mh00h1 and mh00h2. I also have modelA that defines the following in my models.py:
class Meta:
permissions = (
('read','read'),
('write','write'),
)
From a shell, I went to set permissions:
>>>> frhde = create modelA instance
>>>> assign_perm('read', mh00h2, frhde)
DoesNotExist: Permission matching query does not exist. Lookup parameters were {'codename': u'read', 'content_type': <ContentType: modelA>}
I realized that South didn't migrate my models after I added class Meta to modelA and confirmed this. Changing read to read2 shows that South does not detect the change.
$ /manage.py schemamigration myapp --auto
Running migrations for myapp:
- Nothing to migrate.
- Loading initial data for myapp.
Installed 0 object(s) from 0 fixture(s)
Running migrations for guardian:
- Nothing to migrate.
- Loading initial data for guardian.
Installed 0 object(s) from 0 fixture(s)
How can I get schematicmigration to correctly update the database, or is there a better way to do this that does not require redoing the whole database?
Thank you.
You can use ./manage.py syncdb --all, or create a signal like in this post.
To output my database to json file I would usually do
python manage.py dumptdata --indent=4 > mydata.json
However upon executing the following two commands to setup south:
python manage.py schemamigration myproj --initial
python manage.py migrate myproj --fake
I noticed that two of my booleans in mytable for an entry were switched from FALSE to TRUE! I see that from my GUI Web Interface interacting with the database however to more closely compare what changed and got corrupted I'd like to compare json to json but with south enabled I can no longer use the above command as it tells me
Not synced (use migrations):
- myproj
My table that had entries affected is below, I could have more affected data that I have not uncovered.
class MyConfig(models.Model):
name = models.CharField(max_length=64)
myConfigName = models.CharField(max_length=64, unique=True)
myA = models.ForeignKey(MyA)
myB = models.ForeignKey(MyB)
myBoolA = models.BooleanField()
myBoolB = models.BooleanField()
myBoolC = models.BooleanField()
class Meta:
unique_together = ('name', 'myA', 'myB')
def __unicode__(self):
return '%s_%s_%s' % (self.myA.name, self.myB.name, self.name)
schemamigration and migrate --fake don't modify the database. Do you have any initial_data fixture that could be reloaded when migrating? See https://docs.djangoproject.com/en/1.3/howto/initial-data/
Try to migrate with:
python manage.py migrate --no-initial-data
see south doc for more info about options
I don't think that either an --initial or a --fake should alter the database at all, so I'm surprised that it would modify data. In terms of why you're getting the "Not synced (use migrations)" error, I think it's likely because you faked the initial migration.
Try un-migrating the --fake and re-applying the initial migration with
python manage.py migrate --fake zero
python manage.py migrate
Then, you should be able to do the dumptdata