handlers.md

How to create and use handlers

Some people call handlers "controllers" or even "views". Here, we'll refer to them as handlers.

Even though Flask is used in this starter template, the way the handlers (and also routes) are created is not usual in the Flask world.

Usually, a Flask handler looks like this:

@app.route('/')
def hello():
    name = request.args.get("name", "World")
    return render_template("hello.html", name=name)

But in this template we separate routes from the handler functions. We keep URL routes in the main.py file and they look something like this:

app.add_url_rule(rule="/", endpoint="hello", view_func=hello, methods=["GET"])

In addition, we wrap our handler functions with one of these decorators (defined in utils/decorators.py):

• @public_handler
• @login_required
• @admin_required

All of these handlers prepare a dictionary called params that holds all the variables sent from the backedn Python code to the HTML templates. A very common such variable is called now and it sends the current datetime info into all HTML files (this can be used, for example in the footer to get the current year).

Because the way params are used, we have to create handler functions like this:

@public_handler
def hello(**params):
    params["name"] = "World"
    return render_template("hello.html", **params)

You've probably noticed that render_template_with_translations() is used instead of render_template(). This is so we can enable translations, but if you don't want to use the translation system, you can use render_template() instead.

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