I have a Django app running on AWS elastic beanstalk. It was previously connected to a MySQL RDS instance. I have been through several steps to migrate the data from a MySQL instance to a PostgreSQL instance.
In brief I connected to the postgres instance and ran python manage.py migrate
I then ran python manage.py sqlflush and ran the resulting SQL commands
Then I imported a json fixture of content types from the MySQL db. I created the fixture (when connected to the MySQL db) with
python manage.py dumpdata contenttypes --indent=4 --natural-foreign > contenttype.json
and imported it into the PostgreSQL db with
python manage.py loaddata contenttype.json
The above preserves PKs and FKs
I then used AWS DMS to load the data from the MySQL instance to the PostgreSQL instance.
Using the Django app (e.g. through Django admin) all the data can be read from the Postgres instance. However, trying to post data to the database results in a 500 error.
Could this be a problem with security settings in AWS? It seems odd that I can read data from the DB but not post to it.
I've tried connecting to the DB using pgAdmin 4 with the same connection settings. I was able to use an INSERT statement to post to the database from there (but had to explicitly state the PK value)
Update
As suggested by Mark B the problem was Primary Keys. Many of the sequences in postgres had been reset to 1 as the current value. Finding the max value of the ID (PK) in each table and updating the corresponding sequence has got everything working. This question on sequences and primary keys was useful.
Related
I have deployed my app to Azure with Kubernetes. I have separate pods for front end, back end and database. I encountered problems when one of my database fields changed from id to userId. I have tried to update this change to my deployment database but without any luck. I logged into my back end pod and removed the existing migration file and run python manage.py makemigrations & python manage.py migrate. After these I checked that everything was ok in the migration file. After this I don't know what to do. Do I need to remove the database pod and create it again? Or how do I update the database inside the pod?
id -> userId change is a DDL change for your DB. I suggest that you "exec" into your DB pod and start your DB shell.
kubectl exec -it mysql-pod-name bash
Then you should be able to execute your DDL statement. MySql example:
ALTER TABLE tableName
RENAME COLUMN id TO userId;
We three working with Django and postgres is the database. Whenever we push the code to GitHub. The database data is not reflecting. The data I stored is visible to me only. The postgres user, password and database name are same on all our laptops. How to make when I push that has to go their databases also.
If you are talking about changes in db schema, then take a look django migrations - https://docs.djangoproject.com/en/3.1/topics/migrations/. The workflow is following:
change model (e.g. add new field, change existing field...)
generate migration file by running python manage.py makemigrations. This generates migration file in <app_folder>/migrations
Run python manage.py migrate to apply changes in models to your database
Add migration file to your version control (github or whaever) and push it
Now when your colleagues gets updated code from version control they need to run python manage.py migrate to apply model changes to their local database.
I found that it is not possible to send postgress data directly. But sqlite can be used for it. This link aids in that - https://manuelvanrijn.nl/blog/2012/01/18/convert-postgresql-to-sqlite/ . But i send data by taking backup like
From Postgres to Postgres: taking backup :
pg_dump dbname > dbname.bak
and then on new Postgres restored with:
psql test < dbname.bak
My django application is working perfectly fetching and inserting data into local postgres database. Now i have data in my local postgres database. When i deployed my app on heroku and run migrate command in heroku then it create the tables. But the tables are empty.
I just want to know that Did i have to insert all my data again in heroku postgres database or there is any way to migrate/export the local postgres database with data to heroku postgres database?
you can use django-admin dumpdata and django-admin loaddata commands
run the first command in your local machine and upload the generated file to your server and run the loaddata command on your server to restore your data
further reading example docs
I'm new to Django but I'm deploying a Django-based website to Heroku, using Postgresql. The deployment was successful, and the website is online and has established connection with the database. However, none of the data from my local database has migrated to the heroku database, causing it to be a blank database. If I go into the admin section and manually input a datapoint, it appears on my site, so I know that database is correctly serving data. What is the proper way for migrating data from your local database to your online, heroku version of the database? I thought the following code would migrate the data:
heroku run python manage.py makemigrations
heroku run python manage.py migrate
But apparently I'm missing something.
make migrations will create a migration that contains your schema, but no data. The migrate command applies the migration to the database.
In order to provide data to be sent over as part of the migrate command you need to either create a data migration or use a fixture.
Another option you have is to dump your local database and do an import into Heroku Postgres
All in all, it depends on how much local data you have that you want copied over. If its only a few rows, I would use either a data migration or a fixture, if its 100s or 1000s of rows an export/import of your dataset is your best bet.
How does one migrate their Django .sql3 development database to heroku?
Per here, and here I tried: heroku pg:psql --app sblic < database.sql3 but my Django admin shows no new uploads (even after syncdb/migrate/ or collectstatic
Perhaps there may be a way to directly upload an sql3 file to Heroku, but I went with the path of clearest certainty (convert local sql3 db to postgre db and upload a dump of postgre db to Heroku via pgbackups tool):
Create a dump of your sql3 database as a json file
With PostgreSql installed and with its bin directory in the Path environment variable, create a postgre user and database (or just plan on using your initial super user account created upon installing postgresql)
Update your settings.py with a reference to your newly created postgre database (note, 'HOST' may need to be set as 'localhost', 'user' is your postgre user login)
run python manage.py syncdb to initiate your new postgre db
Optional: if necessary, truncate your postgre db of contenttypes
load your dump from step 1 (if you have fixture issues, see here)
Now you have a working postgre local db. To migrate, first create a postgre dump
Post your postgre dump somewhere accessible by URL (such as drop box or amazon s3 as suggested in previous link).
Perform pgbackups restore command, referencing your dump url
Your heroku app should now reference the contents of your local db.
Heroku command line tool uses the psql binary. You have to install PostgreSQL on your local development machine to have psql available. From the (documentation)[https://devcenter.heroku.com/articles/heroku-postgresql#pg-psql]:
You must have PostgreSQL installed on your system to use heroku pg:psql.
You can in fact keep using your SQLite database with Heroku, but this is not recommended as it will be rewritten with your local copy if you re-deploy it to another dyno. Migrating the data to psql is recommended as described at https://devcenter.heroku.com/articles/sqlite3