Implementing a NoSQL backend - python

We have our own custom NoSQL storage system (sort of a document database), and we want a Django app above it.
I want to write a backend that will allow me to connect to our database. I don't care about the Django ORM because we have our own library for querying our database.
What would be the simplest & quickest way of doing this? Rewriting
& overriding the django.db.backends.base classes seems too much of
a hassle since we don't care about Django's ORM. What we basically
need is a way to keep a connection alive, and have the queries run
against the database from our views.py file
If we want to keep the Django auth system, should we rewrite that part so that Django creates the User model etc. in our DB? Perhaps we should have two databases, a simple RDBMS for the authentication part, and the rest of the data in our custom database?
Thanks in advance!

Related

Use Django with MongoDB

I have a large mongo database with documents and i want to make Django website that is going to be a client to this mongo database but it can only filter (aggregate) and view information from database without any edit/update operations. I don't want to put other web site data (users' data, comments, other information) to mongo db.
I'm new to django framework and i wonder if it is better to connect mongodb and django using, for example, mongoengine and use two databases (one for the web site data, and the second one for external documents in mongodb) or use pymongo inside django to fetch data from external db and somehow transform it to djungo models?
Yup, you're spot on, in your case of needing two separate databases, it would be better to use mongoengine in order to use two separate databases. Check out this link. It goes over defining what database to use on a per-model basis so to say.
That most likely would work great. Basically you can query using the model the same way, regardless of the database is uses, but describe which database to use on the model itself.
Hope this helps!

Handle connections to user defined DB in Django

I have pretty simple model. User defines url and database name for his own Postgres server. My django backend fetches some info from client DB to make some calculations, analytics and draw some graphs.
How to handle connections? Create new one when client opens a page, or keep connections alive all the time?(about 250-300 possible clients)
Can I use Django ORM or smth like SQLAlchemy? Or even psycopg library?
Does anyone tackle such a problem before?
Thanks
In your case, I would rather go with Django internal implementation and follow Django ORM as you will not need to worry about handling connection and different exceptions that may arise during your own implementation of DAO model in your code.
As per your requirement, you need to access user database, there still exists overhead for individual users to create db and setup something to connect with your codebase. So, I thinking sticking with Django will be more profound.

Changing Database in run time and making the changes reflect in Django in run time

I am developing a Cloud based data analysis tool, and I am using Django(1.10) for that.
I have to add columns to the existing tables, create new tables, change data-type of columns(part of data-cleaning activity) at the run time and can't figure out a way to update/reflect those changes, in run time, in the Django model, because those changes will be required in further analysis process.
I have looked into 'inspectdb' and 'syncdb', but all of these options would require taking the portal offline and then making those changes, which I don't want.
Please can you suggest a solution or a work-around of how to achieve this.
Also, is there a way in which I can select what database I want to work from the list of databases on my MySQL server, after running Django.
Django's ORM might not be the right tool for you if you need to change your schema (or db) online - the schema is defined in python modules and loaded once when Django's web server starts.
You can still use Django's templates, forms and other libraries and write your own custom DB access layer that manipulates a DB dynamically using python.

Can I use an external database table for the login process in Django?

So I'm starting a new Django project that essentially requires the login & registration process be routed through an EXTERNAL & ALREADY created database.
Is it possible to have the User model use an EXTERNAL database table ONLY when Django is:
Logging in a user, to check if the login is valid
Registering a user, inserting data for that user in the external database
I would like for the rest of the Django server to use a local database.
If so, could someone either provide examples or guide me to documentation on the subject?
Easiest way to use multiple database with Django is to use a database routing. By default Django stick to single database, however, if you want to implement more interesting database routing system, you can define and install your own database routers.
Database routers are installed using the DATABASE_ROUTERS setting. You have to specify this setting in your settings.py file
What you have to do is write one AuthRouter as described Django documentation Django Multiple Database
"Yes, but"
What you are looking for in the docs is called "database router".
There is even an example for the auth app in the docs there.
But, there is s serious drawback to consider with this approach:
We cannot have cross-database relationships in the models. If auth tables are in a separate database, this means that any otehr app that needs a foreign key to User model is going to run into problems. You might be able to "fake" the relationships using a db that doesn't enforce relationship checks (SQLite or MyISAM/MySQL).
Out of the box, such apps are: session, authtoken, and admin (and probably more).
Alternatively, a single-sign-on solution might do a better job: django-sso, or django-mama-cas + django-cas-ng, or the commercial Stormpath.

Django app as database web based UI

I'm planning to develop web UI something like iSQL*Plus-oracle but, for most common databases. Just take input query from user and return result with save options,etc.
So, for connecting to external data bases, what is advisable way,
1. Using django model and raw sql or,
2. with modules outside django - sqlalchemy+mysqldb,psycopg..?
Going through django documentation my understanding is db connections has to be in settings.py and I could not add from user input. Is my understanding is true or not?
I'm new to django not to python.
An ORM (something like Django's models or sqlalchemy) is a really helpful abstraction to help map tabular data in the database to the objects its being used to model in your code. It won't help with connecting to databases provided by the user since you won't know what the schema of the database is you're connecting to, nor what you are going to receive back from a query.
With django, the database defined in settings.py is used to store information related to your app such as user credentials, migrations as well as whatever else you define in your models.py files. So definitely don't try to change that dynamically as it is being used to store the state of your application for all users.
If you need to connect to external databases and run user-supplied queries, you can do that inside a view using the appropriate database driver. So psycopg2 for postgres would be fine.

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