PHP - read variable from string then replace with variable from Database - php

Question

In my PHP forum i want people to insert pictures just by inserting the number/ID of the picture (which they can see in an online photoalbum)
I am looking for a function that can read a string from their posts for example
"bla bla and look at this amazing picture [IMG]234[/IMG] isn't it awesome ..."
then finds the picture in a database with the ID 234 and replaces [IMG]234[/IMG] with
<img src = "path/to/image.jpg" />
preg_replace wouldn't work :( does anyone have an Idea?
thanks for Your help in advance

Answer 1

I would do it in this way:
$images = array();
$post = preg_replace_callback('|\[img\](\d+)\[/img\]|i', function($matches) use(&$images) {
$images[] = $matches[1];
return '__image_' . $matches[1];
}, $post);
if (count($images)) {
// Select images
$imageIds = implode(',', $images);
// DB query
$res = mysql_query("SELECT id, path FROM post_images WHERE id IN ({$imageIds})") or die(mysql_error());
// Replace
while (($row = mysql_fetch_assoc($res))) {
$post = str_replace('__image_'.$row['id'], '<img src=' . $row['path'] . ' />', $post);
}
}
The advantage is that you make only one query to database. This is always important to minimize them to increase performance. if you don't care or you are sure that the number of images in not going to be too high, you can simple use this code:
$post = preg_replace_callback('|\[img\](\d+)\[/img\]|i', function($matches) {
$res = mysql_query("SELECT path FROM post_images WHERE id = {$matches[1]}") or die(mysql_error());
$path = mysql_result($res, 0);
return "<img src='$path' />";
}, $post);

Answer 2

here is what i did:
$find = preg_match_all("!\[img\][0-9]+\[\/img\]!", $post, $matches);
foreach ($matches as $match) {
foreach ($match as $ma) {
$res = str_replace("[/img]","", str_replace("[img]", "",$ma));
$query = "
SELECT
path
FROM
table
WHERE id = '".$res."'
";
$result = mysql_query($query, $conn) or die(mysql_error());
while($line = mysql_fetch_array($result)) {
$path = $line["path"];
$path = "<img src = '".$path. "'></img>";
$post = str_replace ("[img]" . $res . "[/img]", $path, $post);
}
}
}
note: i don't know why preg_match_all creates a 2 depths array

Answer 3

Your code needs to make a db call to get the path from the ID.
Use a tag parser or basic regex to match \[img][0-9]+\[/img]. (preg_match)
Then query your database for the path with the match result as the ID.
Finally, use str_replace to replace the original "[img]$match[/img]" with
Example (pseudo, look these functions up first)
$matches = preg_match_all('\[img][0-9]+\[/img]', $input);
$output = $input;
foreach ($matches as $match) {
$cur = mysql_query("SELECT path FROM table WHERE ID = $match");
$row = mysql_fetch_array($cur);
$output = str_replace('[img]'.$match.'[/img]',$row['path'],$output);
}
Note: this will only work with tags in lowercasse: img and not with IMG, iMG, ImG and so on.

Answer 4

Why doesn't preg_replace work? Not knowing the the details, I would guess that you are not escaping the square brackets. What does your regular expression look like? Try something like
/\[IMG\](\d+)\[/IMG]/
The image id will then be in the group 1, i.e. $1.
Example:
preg_match_all('/\[IMG\](\d+)\[/IMG]/', $post, $matches);
foreach ($matches as $match) {
echo "Image number: " . $match[1] . "\n";
}