PHP Loop through JSON to create a new array

Question

I am not sure why I am having such a hard time with this but I have some Decoded JSON and I want to loop through it to build a smaller array using some of the data.

Below is my JSON $jsonData:

{
  "resultsPage": {
    "results": {
      "event": [
        {
          "id":11129128,
          "type":"Concert",
          "uri":"http://www.songkick.com/concerts/11129128-wild-flag-at-fillmore?utm_source=PARTNER_ID&utm_medium=partner",
          "displayName":"Wild Flag at The Fillmore (April 18, 2012)",
          "start": {
            "time":"20:00:00",
            "date":"2012-04-18",
            "datetime":"2012-04-18T20:00:00-0800"
          },
       location": {
            "city":"Chicago, IL, US",
            "lng":-134.903409,
            "lat":37.7842398
          },
          "venue": {
            "id":6239,
            "displayName":"The Fillmore",
            "uri":"http://www.songkick.com/venues/6239-fillmore?utm_source=PARTNER_ID&utm_medium=partner",
            "lng":-122.4332937,
            "lat":37.7842398,
            "metroArea": {
              "id":26330,
              "uri":"http://www.songkick.com/metro_areas/26330-us-sf-bay-area?utm_source=PARTNER_ID&utm_medium=partner",
              "displayName":"SF Bay Area",
              "country": { "displayName":"US" },
              "state": { "displayName":"CA" }
            }
          },
          "status":"ok",
          "popularity":0.012763
        },
        {
          "id":7923094,
          "type":"Concert",
          "uri":"http://www.songkick.com/concerts/11129128-wild-flag-at-fillmore?utm_source=PARTNER_ID&utm_medium=partner",
          "displayName":"Wild Flag at The Fillmore (April 18, 2012)",
          "start": {
            "time":"20:00:00",
            "date":"2012-04-18",
            "datetime":"2012-04-18T20:00:00-0800"
          },
       location": {
            "city":"New York, NY, US",
            "lng":63.902374,
            "lat":49.7842328
          },
          "venue": {
            "id":6239,
            "displayName":"The Fillmore",
            "uri":"http://www.songkick.com/venues/6239-fillmore?utm_source=PARTNER_ID&utm_medium=partner",
            "lng":-122.4332937,
            "lat":37.7842398,
            "metroArea": {
              "id":26330,
              "uri":"http://www.songkick.com/metro_areas/26330-us-sf-bay-area?utm_source=PARTNER_ID&utm_medium=partner",
              "displayName":"SF Bay Area",
              "country": { "displayName":"US" },
              "state": { "displayName":"CA" }
            }
          },
          "status":"ok",
          "popularity":0.012763
        },

        {
          "id":89763146,
          "type":"Concert",
          "uri":"http://www.songkick.com/concerts/11129128-wild-flag-at-fillmore?utm_source=PARTNER_ID&utm_medium=partner",
          "displayName":"Wild Flag at The Fillmore (April 18, 2012)",
          "start": {
            "time":"20:00:00",
            "date":"2012-04-18",
            "datetime":"2012-04-18T20:00:00-0800"
          },
       location": {
            "city":"Miami, FL, US",
            "lng":42.1238243,
            "lat":50.7289731
          },
          "venue": {
            "id":6239,
            "displayName":"The Fillmore",
            "uri":"http://www.songkick.com/venues/6239-fillmore?utm_source=PARTNER_ID&utm_medium=partner",
            "lng":-122.4332937,
            "lat":37.7842398,
            "metroArea": {
              "id":26330,
              "uri":"http://www.songkick.com/metro_areas/26330-us-sf-bay-area?utm_source=PARTNER_ID&utm_medium=partner",
              "displayName":"SF Bay Area",
              "country": { "displayName":"US" },
              "state": { "displayName":"CA" }
            }
          },
          "status":"ok",
          "popularity":0.012763
        }
      ]
    },
    "totalEntries":24,
    "perPage":50,
    "page":1,
    "status":"ok"
  }
}

Below is my first try at looping through the JSON variable and parsing out the data I want into a new array. I am not sure if I should use push or if there is a more effiecent way to parse the data I want into a new array:

$newArray = array();

foreach($jsonData['resultsPage']['results']['event'] as $val){

$newArray .= "{'id' => $val['id'], 'long' => $val['location']['lng'], 'lat' => $val['location']['lat']}"

}

Answer 1

Try this:

$jsondata_array = json_decode($jsonData, true);

$new_required_arr = $jsondata_array['resultsPage']['results']['event'];

foreach($new_required_arr as $key => $val)
{
  //Your logic to create new array with required key value pair.
}

Answer 2

The problem with you loop is when the element don't exist you get an error because you try to access an element in your array which doesn't exist.

foreach($jsonData as $val) {
}

Then you can work insight with your values and you should check them with isset. Or you make an if statement around your loop to prevent it that problem.

The next problem is that you define $newArray as an array. But the . is to concat a string. So you should define your initial variable like this:

$newArray = '';

The last thing is i can't see it in your code but to parse a json string you have to use json_decode first. To get an object. If you want an array you have to set the second parameter to true.

$arr = json_decode($myjson, true);

Answer 3

The provided JSON format is wrong, the index location missing the double quote at the beginning.

To parse the JSON , you can convert JSON to array and loop through the array to apply your logic OR build new array, you can use json_decode with true parameter.

$arr = json_decode($json, true);
foreach($arr as $k => $v){
  //Your logic
}