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Is it possible to use 2 different frameworks in 1 backend of a web app?

I am an 11th grade student and I'm learning how to build a web app, with my teammates. Currently, We're making a website showing the school schedule (also to show students' marks) and helping the users to create their to-do lists, of course this web serves students like me. In the backend of the web, we use Python as the main language, Flask as the framework and MySQL to manipulate our database. Now, everything is ok and we're trying to make something like an admin interface for people who host the web. Specifically, it is where teachers can insert their students' grade, and maybe adjust the school timetable. The problem is, we're learning how to use Flask Admin to code that function, and we've found out this tech is only compatible with SQL Server. However, we have a better understand in MySQL therefore we could create multiple tasks, in contrast, we don't know how to use SQL Server to create those funcs. Now I have 2 main questions:
Could we use 2 different SQL in the backend of our web? It is the quickest way we know, however we have to learn how to use SQL Server.
Could we use 2 different Python backend frameworks in the backend of our web? We haven't searched which framework to use yet because we don't know if it's possible to do this.
We don't know any other ways to solve this problem except getting rid of MySQL and use SQL Server instead. However this is not the way we prefer and we hope those 2 questions answered. If there is anything wrong in our knowledge please just straightly comment to let us know, and we greatly welcome any other solutions. Thanks for answering!!

Directly from the flask-admin docs https://flask-admin.readthedocs.io/en/latest/advanced/#using-different-database-backends is the following:
Using Different Database Backends Other than SQLAlchemy… There are
five different backends for you to choose from, depending on which
database you would like to use for your application. If, however, you
need to implement your own database backend, have a look at Adding A
Model Backend.
If you don’t know where to start, but you’re familiar with relational
databases, then you should probably look at using SQLAlchemy. It
is a full-featured toolkit, with support for SQLite, PostgreSQL,
MySQL, Oracle and MS-SQL amongst others. It really comes into its own once you have lots of data, and a fair amount of relations between
your data models. If you want to track spatial data like
latitude/longitude points, you should look into GeoAlchemy, as well.
Regarding the original question, it is possible to use two different frameworks in the backend of a web app. One way to do so would be to set up a reverse proxy server (see https://www.nginx.com/resources/glossary/reverse-proxy-server/#:~:text=A%20reverse%20proxy%20server%20is,traffic%20between%20clients%20and%20servers.), but I would recommend giving SQLAlchemy before doing so.

Why do you think that flask-admin is tied to SqlServer? Flask (and flask-admin) can handle different connections to various databases:
https://github.com/flask-admin/flask-admin#introduction
https://flask-admin.readthedocs.io/en/v1.0.9/db/
My guess is you are currently using SqlAlchemy. As explained here, you can use different backends:
The string form of the URL is dialect[+driver]://user:password#host/dbname[?key=value..], where dialect is a database name such as mysql, oracle, postgresql, etc., and driver the name of a DBAPI, such as psycopg2, pyodbc, cx_oracle, etc.
Alternatively, the URL can be an instance of URL.
(https://docs.sqlalchemy.org/en/13/core/engines.html#sqlalchemy.create_engine)
More on Engine here
Flask-admin is a admin view on your database tables - you cannot run it on a "different" db then the tables it should modify. It needs to have access to the database tables you want it to modify, so you cannot run "admin" on MS and "your data backend" on another database(-connection).
Some other things to think about:
MS-(T-)Sql and MySql are infrastructural choices, language wise they are very closely related so adapting MySql knowledge to T-SQL Syntax should be possible. Choosing SqlServer may force you to license it - and afaik that comes with fees (eiter on premise or as a azure subscription wich might or might not be free for schools (no idea - but you should check that)).
This sounds like an ambitious project for school - depending on where you live, privat data protection laws come into play especially considering you connect names with schedules with grades which would need you to implement a lot more to comply.

For first question, I checked flask-admin documentation and found that the framework already included serval built-in ORM library, i.e. SQLAlchemy, MongoEngine, pymongo and Peewee. This means you can just directly import the ORM library from the flask-admin package and use it to access your database. For your case, you should look for SQLAlchemy as you are using SQL Database. Both SQL Server and MySQL are supported by SQLAlchemy.
The Adding Model Views section in their official doc also mentioned it as well:
https://flask-admin.readthedocs.io/en/latest/introduction/#getting-started
For the second question, it is technically not possible to apply two different frameworks in one single backend application.

How to generate complex ORM code and REST API with swagger-codegen?

swagger-editor is with codegen tool built in, so I can generate server side code with it. I try the pet store example, and it works. Then my next try is to think about data persistence. I google around, and I often use Python/Java, so I focus on this 2 languages.
First I would like to try python.
In the swagger-codegen tool, it depends on flask/connexion/flask-swagg and so on, so I think connexion is a good start for me. However when I read the generated code, I found that swagger-codegen inherits swagger data Model itself, and I can use connexion with SQLAlchemy to implement db ORM. For example
Connexion-Example. Also I found SAFRS a good place to go, with this I can easily expose all the DB models as REST API, so that I don't need to create duplicate ORM code myself. So I try to find some suggestions, which can help me out, because now I am stuck.
I want to create a API specification file(yaml or json in swagger-editor), and also the DB model. Then generate server side code, including DB model with SQLAlchemy, with all the DB CRUD ops as REST API. My first thinking is to modify swagger template in swagger-codegen, to use SAFRS or connexion. But I would like to discuss here to get some advise on how you manage to do this kind of work?
Thanks.
Andes

Django Admin using RESTful API v.s. Database

This is a bit of a strange question, I know, but bear with me. We've developed a RESTful platform using Python for one of our iPhone apps. The webapp version has been built using Django, which makes use of this API as well. We were thinking it would be a great idea to use Django's built-in control panel capabilities to help manage the data.
This itself isn't the issue. The problem is that everyone has decided it would be best of the admin center was essentially a client that sits on top of the RESTful platform.
So, my question is, is there a way to manipulate the model layer of Django to access our API directly, rather than communicated directly with the database? The model layer would act as the client passing requests and responses to and from the admin center.
I'm sure this is possible, but I'm not so sure as to where I would start. Any input?

I remember I once thought about doing such thing. At the time, I created a custom Manager using a custom QuerySet. And I overrode some methods such as _filter_or_exclude(), count(), exists(), select_related(), ... and added some properties. It took less than a week to become a total mess that had probably no chance to work one day. So I immediately stopped everything and found a more suitable solution.
If I had to do it once again, I would take a long time to consider alternatives. And if it really sounds like the best thing to do, I'd probably create a custom database backend. This backend would, rather than converting Django ORM queries to SQL queries, convert them to HTTP requests.
To do so, I think the best starting point would be to get familiar with django source code concerning database backends.
I also think there are some important things to consider before starting such development:
Is the API able to handle any Django ORM request? Put another way: Will any Django ORM query be translatable to an API request?
If not, may "untranslatable" queries be safely ignored? For instance, an ORDER BY clause might be safe to ignore. While a GROUP BY clause is very unlikely to be safely dismissed.
If some queries can't be neither translated nor ignored, may them be reasonably emulated. For instance, if your API does not support a COUNT() operation, you could emulate it by getting the whole data and count it in python with len(), but is this reasonable?
If they are still some queries that you won't be able to handle (which is more than likely): Are all "common" queries (in this case, all queries potentially used by Django Admin) covered and will it be possible to upgrade the API if an uncovered case is discovered lately or is introduced in a future version of Django?
According to the use case, there are probably tons of other considerations to take, such as:
the integrity of the data
support of transactions
the timing of a query which will be probably much higher than just querying a local (or even remote) database.

Choosing the right database system for a Django web application

I am currently in the planning stages of building a simple Django web app (for learning proposes). Basically, teacher’s can login, input student grades, and then the students can login and view their grades. Each class has a group number.
Here is a template of a user:
Username: Johny098
Password: Y98uj*?877!(
Name: John Doe
Gender: Male
Group: 32
Secondary: 5
Taking into consideration that I am starting with django and web developpement in general, I find confusing the number of database systems that are available to me: MySQL, CouchDB, MongoDB, SQLite, etc. And I am having a hard time deciding which database system to use for my purpose (I have no prior experience with databases).
After some research I found Couchdb (and SQLite) which seems fairly simple to pick up and fun to use, but that's just me, and that's why I need help. I know there are numerous debates on SQL vs NoSQL, but I don't really know if this will have an impact for my use of the databases. Ideally, the database system should integrate well with django and be easy enough to pick up in a couple of days.
So, coming back to the question: What database system should I use for my web app?
Any resources would also be appreciated.
Thanks,
-Raphael

For learning purposes I'd recommend SQLite: no setup, no background daemons running, everything is bundled with Python, it's SQL (so it maps well with Django ORM), and it's a very simple DBMS. In fact, some people use SQLite for prototyping and then switch to MySQL/PostgreSQL in production.
As for NoSQL, I would not recommend to use it unless you know exactly why and for what purpose you need it.
Oh, and one last thing: store password hashes (md5 or sha1), not the raw passwords. It's not necessary in your case, but in real-world apps it's mandatory.

The Django website has a page that lists the database backends supported. However, Django's database access layer is designed to work more or less the same no matter which database backend you're using. There are some differences described on the page I linked, but they shouldn't come up in normal usage if you're writing just a basic web app. So as far as effects on how you write your web app, among the choices listed it really doesn't matter.
Note that all the database backends Django supports are SQL-based, I believe. Accessing the database through Django does eliminate some of the security issues that I believe prompted the NoSQL movement... in any case, NoSQL is something you can pretty much ignore for now.
In your case, I would suggest picking SQLite, simply because it's easier to set up, and you don't want to spend time worrying about how to configure the database when you should be worrying about how to build your web app. The difference between SQLite and most other DBMSs (database management systems) is that SQLite stores each database in a regular file, and the SQLite client works directly with that file. Other DBMSs (like MySQL, PostgreSQL, Oracle, etc.) have a central location for the databases, a server to manage them, and a client that connects to the server and handles all the database access. A server-based DBMS works well for a busy web app, because it has features to handle many simultaneous requests to the database, but since you're just using this as a learning project, you don't need those features.

I would go for MySQL ... why? because among the ones you named, it is the most popular and, better than that, it will give you more credit when looking for a job (for instance, you can go to monster dot com and find how many jabs require you to know MySQL vs how many SQL-Lite).
Also, MySQL is simple and easy to learn, there are many GUI clients (some of which are Open Source) and it has pretty good documentation.

web2py and DB transactions

When exactly the database transaction is being commited? Is it for example at the end of every response generation?
To explain the question: I need to develop a bit more sophisticated application where I have to control DB transactions less or more manually. Especialy I have to be able to design a set of forms with some complex logics behind the forms (some kind of 'wizard') but the database operations must not be commited until the last form and the confirmation.
Of course I could put everything to the session without making any DB change but it's not a solution, the changes are quite complex and realy have to be performed. So the only way is to keep it uncommited.
Now back to the question: if I undertand how is it working in web2py it will be easier for me to decide if thats a good framework for me. I am a java and php programmer, I know python but I don't know web2py yet ...
If you know any web page when it's explained I also wppreciate.
THanks!

you can call db.commit() and db.rollback() pretty much everywhere. If you do not and the action does not raise an exception, it commits before returning a response to the client. If it raises an exception and it is not explicitly caught, it rollsback.

Have you checked out the official documentation? It explains commit policies and distributed transactions pretty well.