通过JSON循环PHP创建一个新数组

Question

我不知道为什么这么难，但我有一些解码的JSON，我想循环使用一些数据来构建一个更小的数组。

下面是我的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"
  }
}

下面是我第一次尝试遍历JSON变量并将我想要的数据解析到一个新的数组中。我不确定是否应该使用push，或者是否有更有效的方法将我想要的数据解析为一个新的数组：

$newArray = array();

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

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

}

Answer 1

尝试如下：

$jsondata_array = json_decode($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

提供的JSON格式是错误的，索引location在开头缺少双引号。

要解析JSON，可以将JSON转换为数组，并通过数组循环应用逻辑或构建新数组，您可以在true参数中使用json_decode。

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

Answer 3

循环的问题是，当元素不存在时，就会得到一个错误，因为您试图访问数组中不存在的元素。

foreach($jsonData as $val) {
}

然后，您可以使用您的值进行洞察，并且应该使用isset检查它们。或者，在循环周围创建一个if语句，以防止出现这个问题。

下一个问题是将$newArray定义为数组。但是.是连接一个字符串。因此，您应该定义您的初始变量如下：

$newArray = '';

最后一件事是，我在代码中看不到它，但是要解析json字符串，必须首先使用json_decode。为了得到一个物体。如果您想要一个数组，就必须将第二个参数设置为true。

$arr = json_decode($myjson, true);