Multiple patterns within regex - php

Question

I have a json and I need to match all "text" keys as well as the "html" keys.
For example, the json could be like below:
[{
"layout":12,
"text":"Lorem",
"html":"<div>Ipsum</div>"
}]
Or it could be like below:
[{
"layout":12,
"settings":{
"text":"Lorem",
"atts":{
"html":"<div>Ipsum</div>"
}
}
}]
The json is not always using the same structure so I have to match the keys and get their values using preg_match_all. I have tried the following to get the value of the "text" key:
preg_match_all('|"text":"([^"]*)"|',$json,$match_txt,PREG_SET_ORDER);
The above works fine for matching a single key. When it comes to matching a second key ("html" in this case) it just doesn't work. I have tried the following:
preg_match_all('|"text|html":"([^"]*)"|',$json,$match_txt,PREG_SET_ORDER);
Can you please give me some hints why the OR operator (text|html) doesn't work? Strangely, the above (multi-pattern) regex works fine when I test it in an online tester but it doesn't work in my php files.

Answer 1

Fixing text|html
You should add text|html to a group, otherwise it will look for "text or html".
|"(text|html)":"([^"]*)"|
Delimiters
This won't currently work with your delimiters though as you use the pipe (|) inside of the expression. You should change your delimiters to something else, here I've used /.
/"(text|html)":"([^"]*)"/
If you still want to use the pipe as your delimiters, you should escape the pipe within the expression.
|"(text\|html)":"([^"]*)"|
If you don't want to manually escape it, preg_quote() can do it for you.
$exp = preg_quote('"(text|html)":"([^"]*)"');
preg_match_all("|{$exp}|",$json,$match_txt,PREG_SET_ORDER);
Parsing JSON
Although that regex will work, it will need additional parsing and it makes more sense to use a recursive function for this.
json_decode() will decode a JSON string into the relative data types. In the example below I've passed an additional argument true which means I will get an associative array where you would normally get an object.
Once findKeyData() is called, it will recursively call itself and work through all of the data until it finds the specified key. If not, it returns null.
function findKeyData($data, $key) {
foreach ($data as $k => $v) {
if (is_array($v)) {
$data = findKeyData($v, $key);
if (! is_null($data)) {
return $data;
}
}
if ($k == $key) {
return $v;
}
}
return null;
}
$json1 = json_decode('[{
"layout":12,
"text":"Lorem",
"html":"<div>Ipsum</div>"
}]', true);
$json2 = json_decode('[{
"layout":12,
"settings":{
"text":"Lorem",
"atts":{
"html":"<div>Ipsum</div>"
}
}
}]', true);
var_dump(findKeyData($json1, 'text')); // Lorem
var_dump(findKeyData($json1, 'html')); // <div>Ipsum</div>
var_dump(findKeyData($json2, 'text')); // Lorem
var_dump(findKeyData($json2, 'html')); // <div>Ipsum</div>

Answer 2

preg_match_all('/"(?:text|html)":"([^"]*)"/',$json,$match_txt,PREG_SET_ORDER);
print $match_txt[0][0]." with group 1: ".$match_txt[0][1]."\n";
print $match_txt[1][0]." with group 1: ".$match_txt[1][1]."\n";
returns:
$ php -f test.php
"text":"Lorem" with group 1: Lorem
"html":"<div>Ipsum</div>" with group 1: <div>Ipsum</div>
The enclosing parentheses are needed : (?:text|html); I couldn't get it to work on https://regex101.com without. ?: means the content of the parentheses will not be captured (i.e., not available in the results).
I also replaced the pipe (|) delimiter with forward slashes since you also have a pipe inside the regex. Another option is to escape the pipe inside the regex: |"(?:text\|html)":"([^"]*)"|.

Answer 3

I don't see any reason to use a regex to parse a valid json string:
array_walk_recursive(json_decode($json, true), function ($v, $k) {
if ( in_array($k, ['text', 'html']) )
echo "$k -> $v\n";
});
demo

Answer 4

You use the Pipe | character as delimiter, I think this will break your regexp. Does it work using another delimiter like
preg_match_all('#"text|html":"([^"]*)"#',$json,$match_txt,PREG_SET_ORDER);
?