I'm using Angular.js for my project. The business logic is developed within Angular I'm just looking for two things:
I need a way for easy user authentication and I don't know how to implement it through Angular.
I need a server side framework that provides a REST Api, an api for implementing a relational data model and good suppport for databases like Postgres or Mysql.
Now I'm using the Django framework for these two things it works perfectly with databases and provides a beautiful api for working with data, but I feel using Django along with angular is not a good solution because I don't use much of the functionalities that Django provides. I just need a simple REST api with a good Data Model api. Any suggestions for me?
I think it really depends what exactly you are using from Django. If the API is simple, you don't use many middleware classes, context processors, etc.. then you could drop it. If you are used to Python there a bunch of lightweight WSGI web frameworks out there, for example Bottle or Flask. They usually perform a little better than Django + they are mostly written so you can easily create REST API's. The "disadvantage" is that if you need specific things like a SQL ORM or some cache handling you have to include these batteries separately and can not use the Django own parts you are probably used to. This also includes to roll your own authentication system.
I think you have to figure out if you really want to rewrite the code. I personally think that the slight performance boost is often not worth the effort and time.
Regarding question 1 (authentication), this blog post + sample explains a great solution : https://github.com/witoldsz/angular-http-auth
I don't know much about Django but I would be surprised if you couldn't change its "rendering mode". I've been using Express (Node.js) to expose a REST api. It was easy to swap from HTML rendering to JSON.
This may not be appropriate for your environment (not sure what platform you are on), but our current project is using AngularJS with a REST-like back-end built with ASP.NET Web API. It all fits really well together. As Web API is built on top of ASP.NET you get authentication 'for free' and there is no shortage of relational database frameworks out there for .NET. We're using Entity Framework Code-First with a bit of Massive thrown in here and there. That works fine for what we need and is really quick and easy to put together but you could also use NHibernate or any of the many other frameworks which are available for .NET.