Python and flask, looping and printing data based on a variable

Question

I have a problem with looping in python and JSON based on a variable. What Im trying to do is to print just one row of JSON data based on one variable that is passed through.

Heres the code for the python file:

@app.route('/<artist_name>/')
def artist(artist_name):
    list = [
        {'artist_name': 'Nirvana', 'album_name': 'Nevermind', 'date_of_release': '1993', 'img': 'https://upload.wikimedia.org/wikipedia/en/b/b7/NirvanaNevermindalbumcover.jpg'},
        {'artist_name': 'Eminem', 'album_name': 'Marshal Mathers LP', 'date_of_release': '2000', 'img': 'http://e.snmc.io/lk/f/l/6b09725acea3aefbafbf503a76885d0c/1612455.jpg'},
        {'artist_name': 'System of a Down', 'album_name': 'Toxicity', 'date_of_release': '2001', 'img': 'http://loudwire.com/files/2015/09/System-of-a-Down-Toxicity.png'},
        {'artist_name': 'Korn', 'album_name': 'Life is Peachy', 'date_of_release': '1996', 'img': 'http://loudwire.com/files/2014/01/Life-is-Peachy.jpg'}
    ]
    return render_template("artist.html", results=list, artist_name=artist_name)

And this is my artist.html template:

{% if results %}
<ul>
{% for item in results if item.artist_name == item.artist_name %}
    <li>{{ item.artist_name }}</li>
    <li>{{ item.date_of_release}}</li>
{% endfor %}
</ul>
{% endif %}

What im trying to achieve is that when an "artist_name" variable is being passed I will be able to print "artist_name" variable and "date_of_release" variable but instead it prints all four records instead of one based on the variable "artist_name". Can anybody help me with this? Thank you.

Maybe because of this: `item.artist_name == item.artist_name`? — hjpotter92, Oct 14 '16 at 13:18
I tried different variations such as item.artist_name == results but I just can't figure out how to do it properly. — Animalovsky, Oct 14 '16 at 13:21
Thanks that works, however it doesn't work for the record in which there are space "System of a down. Is there any fix to that? — Animalovsky, Oct 14 '16 at 13:30

score 0 · Answer 1 · answered Oct 14 '16 at 13:30

my solution is less complicated, and working :)

from flask import Flask,render_template,url_for
import json
app = Flask(__name__)
app.debug = False

@app.route('/<artist_name>/')
def artist(artist_name):
    list = [
        {'artist_name': 'Nirvana', 'album_name': 'Nevermind', 'date_of_release': '1993', 'img': 'https://upload.wikimedia.org/wikipedia/en/b/b7/NirvanaNevermindalbumcover.jpg'},
        {'artist_name': 'Eminem', 'album_name': 'Marshal Mathers LP', 'date_of_release': '2000', 'img': 'http://e.snmc.io/lk/f/l/6b09725acea3aefbafbf503a76885d0c/1612455.jpg'},
        {'artist_name': 'System of a Down', 'album_name': 'Toxicity', 'date_of_release': '2001', 'img': 'http://loudwire.com/files/2015/09/System-of-a-Down-Toxicity.png'},
        {'artist_name': 'Korn', 'album_name': 'Life is Peachy', 'date_of_release': '1996', 'img': 'http://loudwire.com/files/2014/01/Life-is-Peachy.jpg'}
    ]
    res = ""
    for i in list:
        if i.get('artist_name') == artist_name:
            res = i
    return render_template("artist.html", results=list, artist_name=res)    

if __name__ == '__main__':
    app.run(host='0.0.0.0')

template:

{% if results %}
<ul>

    <li>{{ artist_name["artist_name"] }}</li>
    <li>{{ artist_name["date_of_release"]}}</li>

</ul>
{% endif %}

(artist_name in url is case sensitive)

Thank you, that works as well as the answer given by "Markus K" except for the variable with spaces. — Animalovsky, Oct 14 '16 at 13:31

score 0 · Answer 2 · edited May 23 '17 at 10:27

In the comments, H J potter and Markus have it right: however I'ld be very careful over the url encoding of your url and enforcing capitlisation of the artist name: Is "System Of A Down" the same as "System of a Down", and does flask always decode correctly?

{% if results %}
<ul>
{% for item in results if item.artist_name == artist_name %}
    <li>{{ item.artist_name }}</li>
    <li>{{ item.date_of_release}}</li>
{% endfor %}
</ul>
{% endif %}

Have a look at Is a URL allowed to contain a space? TLDR? "Shorter answer: no, you must encode a space; it is correct to encode a space as +, but only in the query string; in the path you must use %20."

I would also go further though and suggest a restructure of the code - try to keep business logic (i.e. deciding not to display or load all the data) in one file, the 'python', and the display logic (deciding to put them on bullet points or on divs) in the other (the 'template')

Thanks, I will have a look at it. – Animalovsky Oct 14 '16 at 13:33 — Animalovsky, Oct 14 '16 at 13:33

Python and flask, looping and printing data based on a variable

2 Answers2