从json数据中提取唯一键名，例如SQL select与**********不同

Question

I have the following json data:

{
   "data": [
      {
         "name": "The Frugalicious Chef",
         "category": "Chef",
         "id": "186397894735983",
         "created_time": "2011-03-07T16:10:35+0000"
      },
      {
         "name": "Siuslaw Broadband",
         "category": "Telecommunication",
         "id": "190373850988171",
         "created_time": "2011-03-06T20:21:42+0000"
      },
      {
         "name": "Paul",
         "category": "Movie",
         "id": "129989595478",
         "created_time": "2011-03-04T19:55:18+0000"
      },
      {
         "name": "Mark Zuckerberg",
         "category": "Public figure",
         "id": "68310606562",
         "created_time": "2011-02-16T09:50:35+0000"
      },

The idea here is that I want to take this data and use parts of it. I want to create a list of the "category's" that are in the data. The problem is that there is and will be multiple items with the same category. So my list will have duplicates that I do not want. The following is how I am getting the data and converting it for use:

$jsonurl = "https://xxxxxxxxxx.com/".$fd_ID. "/info?access_token=".$session['access_token'];
$likesjson = file_get_contents($jsonurl,0,null,null);
$likesArray=json_decode($likesjson);

I then use a foreach to access the data.

foreach($friendLikesArray->data as $l)
{
etc......
}

So I guess muy question is I want to take the $likesArray and pull out all the unique Data->Category->names. Also will want to do sorting, and other things but I will get to that when the time comes.

Thanks for the help in advance. Neil

Answer 1

The data structure you would want to use is a set, that only allows unique entries.

A simple implementation using PHP arrays is to use the keys.

e.g.

$categories = array();

foreach($friendLikesArray->data as $l)
{
    $categories[$l->category] = true;
}

$categories = array_keys($categories);

This way if the category has already been added, then you are not adding anything new to the array.

If the keys are not important to you then you can use the line:

$categories[$l->category] = $l->category

But this means your array won't have 0,1,2...n for keys.