Parse ImmutableMultiDict based on index at end of key strings-CodePudding

I receive a dict of tuples from a Flask/Jinja form:

request.form = (
    [
        ("music_style", "Bossa Nova"),
        ("song_title_1", "Águas De Março"),
        ("song_artists_1", "Elis Regina, Antônio Carlos Jobim"),
        ("song_title_2", "Mas, Que Nada!"),
        ("song_artists_2", "Jorge Ben Jor"),
        ("song_title_3", "Mais Que Nada"),
        ("song_artists_3", "Sergio Mendes & Brasil '66"),
    ]
)

I need it formatted where each indexed set is within it's own object:

post = {
        "music_style": "Bossa Nova"
            {
                "song_title": "Águas De Março",
                "song_artists": "Elis Regina, Antônio Carlos Jobim"
            },
            {
                "song_title": "Mas, Que Nada!",
                "song_artists": "Jorge Ben Jor"
            },
            {
                "song_title": "Mais Que Nada",
                "song_artists": "Sergio Mendes & Brasil '66"
            },
        ],
    }

Where the template utilizes loop.index:

{% for song in class_plan["playlist"] %}
   <input type="hidden" name="song_title_{{ loop.index }}" value="{{ song['track_title'] }}">
{% endfor %}

I know that I can access the numbers with post[i][0][-1] and the strings with post[i][0][:-2], and I have worked out, then could do same for each required key, and finally zip it all up, then perhaps render as a tuple:

titles = [(key[:-2], val) for key, val in post if key[:-2] == 'song_title']
artists = [(key[:-2], val) for key, val in post if key[:-2] == 'song_artists']
songs = zip(titles, artists)
tuple(songs)

((('song_title', 'Águas De Março'), ('song_artists', 'Elis Regina, Antônio Carlos Jobim')), \
(('song_title', 'Mas, Que Nada!'), ('song_artists', 'Jorge Ben Jor')), \
(('song_title', 'Mais Que Nada'), ('song_artists', "Sergio Mendes & Brasil '66")))

Then do something to jsonify it (probably with Flasks jsonify), but I am sure there are much more eloquent (if not correct) and Pythonic approaches and hope you'll enlighten me.

Thanks.

CodePudding user response：

It would probably be easiest to loop over the numbers and build the dictionaries, something like this:

import itertools

songs = []
try:
    for idx in itertools.count(1):
        # access tuple as dict
        post_item = dict(post)
        songs.append({"song_title": post_item["song_title_%d" % idx],
            "song_artists": post_item["song_artists_%d" % idx]})
except LookupError: # or whatever exception signals that there aren't any more
    pass # just halt the loop, nothing more needed

If you prefer to put a hard limit on the number of songs you look up (in case something bizarre happens), you could iterate over range(1, 11) or range(1, 101) etc; and if your numbering starts from zero, omit the 1 from count() or range().