如何访问嵌套的JSON数据 [英] How to access nested JSON data

问题描述

假设我有json数据，如

Let say I have json data like

data = {"id":1,
        "name":"abc",
        "address": {"streetName":"cde",
                    "streetId":2
                    }
        }

现在我要从这个json数据中获取字段，如： fields = [id，name ，address.streetName]

Now I am getting fields to be accessed from this json data like : fields = ["id", "name", "address.streetName"]

我如何访问第三个字段（ address.streetName ）以最有效的方式从给定的json数据？
data.fields [2] 不起作用

How could I access third field (address.streetName) from given json data in most efficient way? data.fields[2] doesn't work

一种可能性是我构建 data [address] [streetName] 使用for循环的字符串并执行eval，但有没有有效的方法呢？

One possibility is I construct data[address][streetName] string using a for loop and do eval of that but is there any efficient way of doing this?

推荐答案

说实话，我无法理解你的问题。 JSON已经结构化了，为什么你需要更改结构？

To be honest, I can't understand your problem. JSON is already structured out, why do you need to change the structure?

在这种情况下，我会按如下方式访问它：

In you case, I would access it as follows:

data.address.streetName;

如果您想要的话，遍历数据，你需要：

If, by any chance, what you want is to traverse the data, you would need:

function traverse_it(obj){
    for(var prop in obj){
        if(typeof obj[prop]=='object'){
            // object
            traverse_it(obj[prop[i]]);
        }else{
            // something else
            alert('The value of '+prop+' is '+obj[prop]+'.');
        }
    }
}

traverse_it(data);

---

更新

阅读下面的内容后，这个用户需要的内容似乎更加明显。将属性名称作为字符串，他/她想要访问该对象。

After reading below, what this user needs seems more obvious. Given property names as a string, s/he wants to access the object.

function findProp(obj, prop, defval){
    if (typeof defval == 'undefined') defval = null;
    prop = prop.split('.');
    for (var i = 0; i < prop.length; i++) {
        if(typeof obj[prop[i]] == 'undefined')
            return defval;
        obj = obj[prop[i]];
    }
    return obj;
}

var data = {"id":1,"name":"abc","address":{"streetName":"cde","streetId":2}};
var props = 'address.streetName';
alert('The value of ' + props + ' is ' + findProp(data, props));

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