Move div based on user voting

Question

I'm new here, but I love the site. I checked through the other similar questions, but I didn't see what I'm looking for.

I'm a musician, and I've been doing a "song of the day" thing for a while where I write a little song every day. I want to post the songs as <div>s inside <li>. In the divs, I just want a simple mp3 player and a "like" or "dislike" button. The user can vote and the song will move up or down the <li> based on the number of votes.

I want to keep this simple with the math-just subtracting the dislikes from the likes in the <li> array and ordering them from highest to lowest.

It'd be good to have a simple cookie system in place to at least keep someone from voting a lot all in one sitting, but I'm not too concerned about it.

I've been looking for a simple PHP or Javascript tutorial on this. Can anyone point me in the right directions? Thanks!

Answer 1

You're going to need a central location to store this song information, mainly the votes, but you might as well through the other song information (like title, path to music file, etc) in there as well. I suggest a simple MySQL table as follows

CREATE TABLE daily_song (
    daily_song_id SMALLINT UNSIGNED NOT NULL AUTO_INCREMENT,
    vote          INT          NOT NULL DEFAULT 0,
    title         VARCHAR(255) NOT NULL DEFAULT "" COMMENT "Name of the song",
    path          VARCHAR(255) NOT NULL DEFAULT "" COMMENT "Path to the song on the server",
    ctime         DATETIME     NOT NULL            COMMENT "Datetime the song was added",
    PRIMARY KEY(daily_song_id)
);

I used the following HTML structure:

<ul id="daily-songs">
    <li id="song-id-1">
        <h3>Song 1</h3>
        <div class="voting-controls">
            <a href="#" class="vote-up">Up</a>
            <div class="votes">8</div>
            <a href="#" class="vote-down">Down</a>
        </div>
        <div class="player"></div>
    </li>
    <li id="song-id-2">
        <h3>Song 2</h3>
        <div class="player"></div>
        <div class="voting-controls">
            <a href="#" class="vote-up">Up</a>
            <div class="votes">5</div>
            <a href="#" class="vote-down">Down</a>
        </div>
    </li>
    <li id="song-id-3">
        <h3>Song 3</h3>
        <div class="player"></div>
        <div class="voting-controls">
            <a href="#" class="vote-up">Up</a>
            <div class="votes">4</div>
            <a href="#" class="vote-down">Down</a>
        </div>
    </li>
</ul>

And a touch of CSS

#daily-songs li { clear: both; list-style: none; }
#daily-songs h3 { margin: 0 10px 0 0; float: left; }
#daily-songs .voting-controls { height: 1em; }
#daily-songs .voting-controls * { float: left; }
#daily-songs .voting-controls .votes { padding: 0 10px; }

Here's the JavaScript, using jQuery

$(function() {
    var listContainer = $("#daily-songs"),
        songs         = [];
    var songSort = function(a, b) {
        return +b.vote.text() - +a.vote.text();
    };

    var submitVote = function(song, delta) {
        $.post("vote.php", 
            {
                id:    song.node.attr("id").match(/\d+$/)[0],
                delta: delta,
                votes: song.vote.text() // temporary
            }, 
            function(data) {
                if ( isNaN(data) ) { return; }
                song.vote.text(data);

                // Re-order the song list
                $.each(songs.sort(songSort), function() {
                    listContainer.append(this.node);
                });
            }
        );
    };

    listContainer.find("li").each(function() {
        var $this = $(this); 
        var song  = {
            node: $this,
            vote: $this.find(".votes")
        };
        $this.find(".vote-up").click(function() {
            submitVote(song, 1);
        });
        $this.find(".vote-down").click(function() {
            submitVote(song, -1);
        });

        songs.push(song);
    });
});

And some stub PHP for vote.php:

<?php

$songId = !empty($_POST['id'])    ? (int)$_POST['id']    : 0;
$delta  = !empty($_POST['delta']) ? (int)$_POST['delta'] : 0;

if ( !$songId || !$delta ) {
    die("Invalid parameters");
}

// Make sure the voting value is within the valid rang
$delta = $delta > 0 ? 1 : -1;

// Check to see if user has already voted for this song,

// If they haven't voted yet, connect to the database

// If the database connection is succesful, update song entry
// UPDATE daily_song SET votes=votes+$delta WHERE daily_song_id=$songId

// If the UPDATE is successful, SELECT the new vote value
// SELECT vote FROM daily_song WHERE daily_song_id=$songId

// Output the new vote value

// But for now, just accept the current vote and apply the delta
echo $_POST['votes'] + $delta;

I'll leave the PHP for you to fill in. Shouldn't be too much of a stretch. Let me know if you have any questions.

Answer 2

Yeah, a MySQL table seems critical, to maintain the votes as you collect them. Then a function to return or output the <li>'s in sorted order, as you are constructing the page. If Justin doesn't come back with more, I will add more later.