array codeigniter with mongoDB

Notice the keys and the strings are quoted and the [ ] around $temp to make it an array, for the second part I convert array[1] into a json string then back into an array then use array_keys to create an array of the keys.

$temp = '{"foo":"bar","bar":"foo"},{"_id":1,"nama":1,"nim":1}';
$temp = "[$temp]";
$array = json_decode($temp);

$keys = array_keys(json_decode(json_encode($array[1]), true));

json_encode json_decode array_keys

Code:

<?php

$str1 = "{foo:bar,bar:foo},{_id:1,nama:1,nim:1}";
preg_match_all('/\{(.+?)\},?/', $str1, $matches);
var_dump($matches[1]);

$str2 = "_id:1,nama:2,nim:3";
preg_match_all('/(\w+)\:\w+,?/', $str2, $matches);
var_dump($matches[1]);

?>

Result:

array
  0 => string 'foo:bar,bar:foo' (length=15)
  1 => string '_id:1,nama:1,nim:1' (length=18)
array
  0 => string '_id' (length=3)
  1 => string 'nama' (length=4)
  2 => string 'nim' (length=3)

Reference:

• preg_match
• preg_split
• preg_match_all

Explaination:

1. First of all, we should decide which function to use. As the manual said:

   preg_match() returns the number of times pattern matches. That will be either 0 times (no match) or 1 time because preg_match() will stop searching after the first match. preg_match_all() on the contrary will continue until it reaches the end of subject. preg_match() returns FALSE if an error occurred.

   and

   preg_split() returns an array containing substrings of subject split along boundaries matched by pattern.

   As your goal is to capture the content between the curly brace, I choose preg_match_all to easily handle the task. Of course, you can do it with preg_split the hard way :)

2. Come to the patterns: it's all about Regular Expression
   1. \{(.+?)\},?: We capture the content inside a pair of curly braces. + stand to skip empty braces like {}. Try put some empty pair {} into $str1 and change + to * and see what happens. Also the ? mark to specify non-greedy. +? mean that we don't need something like foo}{bar from {foo}{bar}, but foo and bar alone. ,? mean there can be a comma or not.
   2. (\w+)\:\w+,?: We capture the key in a pair key:value

Hope this help :)