Outputting HTML unordered list python

Question

I'm attempting to write a function with python that will take an list of strings that I have defined and display them as a single string that is and HTML unordered list of said strings. So far my code is:

def pizzatoppings(self):
    toppings = ['mushrooms', 'peppers', 'pepparoni', 'steak', 'walnuts', 'goat cheese', 'eggplant', 'garlic sauce'];
    for s in toppings:
        ul += "<li>"+str(s)+"</li>"
        ul += "</ul>"
        return ul

When I attempt to run this however I get no traceback and nothing happens. Does anyone know why this is happening? I know this is probably a trivial question but I've searched for answers and cannot find a solution. Thanks!

Solution 1

You could do something like that:

def print_ul(elements):
    print("<ul>")
    for s in elements:
        ul = "<li>" + str(s) + "</li>"
        print(ul)
    print("</ul>")

toppings = ['mushrooms', 'peppers', 'pepparoni', 'steak', 'walnuts', 'goat cheese', 'eggplant', 'garlic sauce'];
print_ul(toppings)

There were some problems with your original code:

• you did not call the function, so no wonder it didn't do anything
• even if you did, the function did not actually print anything, it just returned some values
• the function didn't really take arguments, so it was not re-usable at all

A better (IMO) solution would be to have a function generating the HTML code, and printing the result:

def ulify(elements):
    string = "<ul>\n"
    for s in elements:
        string += "<li>" + str(s) + "</li>\n"
    string += "</ul>"
    return string

print(ulify(['thing', 'other_thing']))

You can also read about list comprehensions. It would make working with lists simpler:

def ulify(elements):
    string = "<ul>\n"
    string += "\n".join(["<li>" + str(s) + "</li>" for s in elements])
    string += "\n</ul>"
    return string
    

Solution 2

Looks like you are trying to build a website. Why don't you use a template engine, like Jinja 2 for this, instead of printing a HTML snippet from a function? For that you will need a Python web application, plausibly written in one of web frameworks. I'd go for Flask here, it's simple to start working with and Jinja is a default template engine for Flask.

If you just want to generate static HTML files, I would recommend Frozen-Flask, which allows you to generate static HTML files that can be hosted without a need to deploy any Python web application on your server. Just copy generated files to your hosting and you are ready to go.

If you still want to just print a HTML snippet, your code should be something like Ealhad posted in his answer.

Also, you original code contains a few problems:

def pizzatoppings(self):
    # you don't need semicolons in Python
    toppings = ['mushrooms', 'peppers', 'pepparoni', 'steak', 'walnuts', 'goat cheese', 'eggplant', 'garlic sauce']
    # you need to initialize a "ul" variable
    ul = "<ul>"
    for s in toppings:
        ul += "<li>"+str(s)+"</li>"
    # following two lines where indented too much. In Python, indentation defines a block of code
    ul += "</ul>"
    return ul

Comments

[Calvin Ellington]

I can't believe I was forgetting to call the function, thanks for your help I've marked your answer as correct.

[Ealhad]

@NoOrangeJuice I'm glad! I can help you improve it a bit if you want ;)

[Calvin Ellington]

Using a function to generate the code looks much simpler actually, thanks again!

[Ealhad]

It's simpler indeed, and much more composable. You can use the generated text in other functions, or even print to a file instead of you terminal. Functions are good, use them! (and especially those which are already built-in!)

[Calvin Ellington]

I'm actually more familiar with template engines, and I agree they are much simple to use. However I'm trying to write the html snippet as a proof of concept kind of thing.