php unique/distinct value from comma seperated value - php

Question

I have a wallposts MySql table with a tag_filter field, this field will have a comma seperated value.
I want to get all the unique/distinct tags for a user from this tag_filter field and populate in ul element.
There could be many posts per user.
eg
post1: tag_filter = a, b, c
post2: tag_filter = a, d, e
post3: tag_filter = c, d, e
the desired output would be
<ul>
<li>a</li>
<li>b</li>
<li>c</li>
<li>d</li>
</ul>
Here is my code thus far:
$tag_filter_list = mysql_query('SELECT tag_filter from wallposts where userid = '.$USER->id);
$list = "<ul>";
while ($tag_filter = mysql_fetch_array($tag_filter_list)) {
$value = $tag_filter["tag_filter"];
$info = explode(",", $value);
foreach( $info as $item ) {
$list.="<li>$item</li>\n";
}
}
$list .= "</ul>";
echo $list;
I would also like to populate a js var with the distinct/unique list acquired from the above.
var sampleTags = [
<?php
$tag_filter_list = mysql_query('SELECT tag_filter from wallposts where userid = '.$USER->id);
$all_tags = array();
while ($tag_filter = mysql_fetch_array($tag_filter_list)) {
$value = $tag_filter["tag_filter"];
$info = explode(",", $value);
$all_tags = array_merge($all_tags, $info);
}
$tags = array_unique($all_tags); // values will be sorted by the function
foreach( $tags as $item ) {
$list = "$item";
}
echo join(',', $list);
?>
];

Answer 1

This might help.
$tag_filter_list = mysql_query('SELECT tag_filter from wallposts where userid = '.$USER->id);
$tags = array();
while ($tag_filter = mysql_fetch_array($tag_filter_list)) {
$value = $tag_filter["tag_filter"];
$tags[] = explode(",", $value); // put all in an array
}
// now, join and remove duplicates and sort in ascending order
$tags = implode( ',', $tags );
$tags = explode( ',', $tags );
$tags = array_values( array_unique( $tags ) );
sort($tags);
$list = "<ul>";
foreach( $tags as $item ) {
$list .= "<li>$item</li>\n";
}
$list .= "</ul>";
echo $list;
Hope this helps.

Answer 2

Comma separated values in a MySQL field is a sign of a bad database design, linked tables should be used if possible.
However, in your case, the following code might work:
$all_tags = array();
while ($tag_filter = mysql_fetch_array($tag_filter_list)) {
$value = $tag_filter["tag_filter"];
$info = explode(",", $value);
$all_tags = array_merge($all_tags, $info);
}
$tags = array_unique($all_tags); // values will be sorted by the function
foreach( $tags as $item ) {
$list .= "<li>$item</li>\n";
}
To put all tags in a javascript variable:
<script type="text/javascript">
var sampleTags = [<?php echo explode(', ', $tags); ?>];
</script>

Answer 3

Try merging all tag_filter arrays with array_merge() and then use array_unique() to remove duplicates.

Answer 4

Just try with the following example :
<?php
$post_array = array('a,b,c','a,d,e','c,d,e');
$tag_list = '<ul>';
$i=0;
while($i < count($post_array)){
$filter_explode = explode(',',$post_array[$i]);
$filter_count = count($filter_explode);
for($j=0;$j<$filter_count;$j++)
{
if(!in_array($filter_explode[$j],$tag_list_build)){
$tag_list_build[] = $filter_explode[$j];
}
}
$i++;
}
$tag_list_build_count = count($tag_list_build);
for($k=0;$k<$tag_list_build_count;$k++)
{
$tag_list.= '<li>'.$tag_list_build[$k].'</li>';
}
$tag_list.= '</ul>';
echo $tag_list;
?>
I think this may help you to resolve your problem.