Question

我正在尝试创建一个loadrunner'js'文件来从json中捕获一些数据。 json文件位于Web服务器上，这不是问题。我可以成功检索json。但是，我想从json文本返回一个特定的值。我试图在本地html页面上执行此操作，如下所示，但我总是收到一条错误消息：

错误是TypeError：无法读取未定义的属性“位置”

代码：

<!doctype html> <head></head><script>

function getdata() 
{
var jsontext = '{"Locations":{"Location":[{"@id":"3649","@latitude":"51.758","@longitude":"-1.576","@country":"England","@zoomLevel":"10","@obsZoomLevel":"5","@type":"Observing Site","@name":"Brize Norton","@geohash":"gcnyknk2h"},{"@id":"3","@latitude":"50.9503","@longitude":"-1.3567","@country":"England","@zoomLevel":"11","@type":"Airport and Heliport","@name":"Southampton    Airport","@geohash":"gcp1c5hp4"}]}}';
var stringifiedjson = JSON.stringify(jsontext).replace(/@/g, '_'); //convert to JSON string
var data = JSON.parse(stringifiedjson);
json.innerHTML=data;

try{
var newlocation0 = data.Locations.Location[1]._id;
output.innerHTML=newlocation0;
return;

}
 catch(err){
    message.innerHTML = "(1)Error is " + err;
}

try{
var newlocation0 = data.Locations.Location[1]._id;
output.innerHTML=newlocation0;
return;
}
 catch(err) {
        message.innerHTML = message.innerHTML + "(2)Error is " + err;
    }

try{
var newlocation0 = data.Locations.Location[0]._id;
output.innerHTML=newlocation0;
return;
}
 catch(err) {
        message.innerHTML = message.innerHTML + "(3)Error is " + err;
    }
}
</script>  
<body>
Error Messages:
<p id="message"></p>
<BR><BR>
JSON Input:
<p id="json"></p>
<BR><BR>
Output:
<p id="output"></p>



<button onclick="getdata()">Check</button> 
<button onclick="location.reload();">Reload</button> 

</body>

我尝试了[0]和[1]符号的不同组合，但我无法获得json右侧部分的输出。

Answer 1

jsontext最初是一个字符串

var jsontext = '{"Locations":{"Location":[{"@id":"3649","@latitude":"51.758","@longitude":"-1.576","@country":"England","@zoomLevel":"10","@obsZoomLevel":"5","@type":"Observing Site","@name":"Brize Norton","@geohash":"gcnyknk2h"},{"@id":"3","@latitude":"50.9503","@longitude":"-1.3567","@country":"England","@zoomLevel":"11","@type":"Airport and Heliport","@name":"Southampton    Airport","@geohash":"gcp1c5hp4"}]}}';

你已将该字符串包装在另一个字符串中

var stringifiedjson = JSON.stringify(jsontext).replace(/@/g, '_');

结果字符串看起来像这样

""{\"Locations\":{\"Location\":[{\"_id\":\"3649\",\"_latitude\":\"51.758\",\"_longitude\":\"-1.576\",\"_country\":\"England\",\"_zoomLevel\":\"10\",\"_obsZoomLevel\":\"5\",\"_type\":\"Observing Site\",\"_name\":\"Brize Norton\",\"_geohash\":\"gcnyknk2h\"},{\"_id\":\"3\",\"_latitude\":\"50.9503\",\"_longitude\":\"-1.3567\",\"_country\":\"England\",\"_zoomLevel\":\"11\",\"_type\":\"Airport and Heliport\",\"_name\":\"Southampton    Airport\",\"_geohash\":\"gcp1c5hp4\"}]}}""

解析一次返回内部JSON字符串

var data = JSON.parse(stringifiedjson);

再次从字符串解析中获取对象

data = JSON.parse(data);

OR

首先不需要JSON.stringify，你可以使用replace方法。

创建LoadRunner脚本以捕获Json数据

1 个答案: