Dynamically generate Flask routes

Question

I am trying to dynamically generate routes in Flask from a list. I want to dynamically generate view functions and endpoints and add them with add_url_rule.

This is what I am trying to do but I get a "mapping overwrite" error:

routes = [
    dict(route="/", func="index", page="index"),
    dict(route="/about", func="about", page="about")
]

for route in routes:
    app.add_url_rule(
        route["route"], #I believe this is the actual url
        route["page"], # this is the name used for url_for (from the docs)
        route["func"]
    )
    app.view_functions[route["func"]] = return render_template("index.html")

Answer 1

You have one problem with two possible solutions. Either:

1. Have route[func] directly reference a function, not a string. In this case, you don't have to assign anything to app.view_functions.

Or:

2. Leave out the third argument of app.add_url_rule, and assign a function to app.view_functions[route["page"]]. The code

   return render_template("index.html")
   

   is not a function. Try something like

   def my_func():
       return render_template("index.html")
   # ...
   app.view_functions[route["page"]] = my_func
   

I'd recommend the first option.

Source: the docs.

---

Alternate solution:

Use variable parts in the URL. Something like this:

@app.route('/<page>')
def index(page):
  if page=='about':
     return render_template('about.html') # for example
  else:
     some_value = do_something_with_page(page) # for example
     return render_template('index.html', my_param=some_value)

Answer 2

Not too familiar with Flask, so it is possible that there is a cleaner way to do this. (If someone who is knowledgeable about Flask thinks that my method is inherently wrong, I'll gladly delete my answer if they explain why in a comment.) Now that I got that disclaimer out of the way, here are my thoughts:

app.route("/") is a decorator function. The @ notation is just syntactic sugar for something like index = app.route("/")(index). Therefore, you should be able to do something like this...

routes = [
    ("/", index),
    ("/about", about)
]
for route, view_func in routes:
    view_func = app.route(route)(view_func)

which would allow you to create the Flask routes from dynamically created routes and functions.