Question

How can I create a widget on the site, such as login forms, dynamic menu (items taken from the database), site statistics?

I know that you can render a template that will extend out of a base template. And in the base template you can create these widgets.

But I do not know how to move the logic from the base template to my code. For example, the selection data for the block. Such actions certainly can be done in the template, but it would be a poor method in my opinion.

Sorry for my bad English. If you can not understand, I’ll try to rephrase.

Answer 1

You would use a python library called WTForms. It helps you write code for creating forms and other widgets backed by database which you can render using jinja2 templates.

    class YourForm(Form):
         your_field1 = TextField()
         ....
         your_fieldn = SubmitField()


   @app.route('/')
   def view():
       form=YourForm()
       return render_template('your.html', form=form)

   In your.html
   <form >
     {{ form.your_field1 }}
     ....
     {{ form.your_fieldn }}
   </form>

Check out this flask pattern for form validation and rendering to know more about it.

Edit: To create global variables available to all templates,there are two ways:

1. You can use global dict of jinja environment.
   This is the code:

      app.jinja_env.globals.update({'variable':1})
   

2. You can use ContextProcessor. Code:

   @app.context_processor
   def inject_variable():
       return dict(variable=1)
   

Now you can access variable in any template of your app.