使用键0/1（而不是键名称）访问JSON

Question

I have json that looks more or less like this:

{
    "TaskCategoryType": [
        {
            "PK_Column_Value": "C",
            "Column_Description": "Consumables"
        },
        //...
    }

I need to retrieve the value of "PK_Column_Value" without knowing the name of the key.

Looping through and getting the record is fine, but I don't want:

row.PK_Column_Value

in my Javascript as, at runtime, I do not know the name "PK_Column_Value", only that it's the first in the 2 column "pair" per json row.

I tried: row[0] but it gives back undefined.

I want to load a select dropdown box with the value of "PK_Column_Value" and the text of "Description", but I want to send through other json data that has a different column name for the value in JSON.

Answer 1

The best you can do is loop and check, different browsers can produce different order of objects:

for (var i = 0; i < data.TaskCategoryType.length; i++) {
    for (var key in data.TaskCategoryType[i]) {
        console.log(data.TaskCategoryType[i][key]) //Your keys
    }
}

Answer 2

The only "clean" way would be to restructure your JSON to contain arrays instead of objects.

{
"TaskCategoryType": [
    [
        "C",
        "Consumables"
    ],
    //...
}

But personally I'd keep it that way, it makes the code much easier to read and maintain.

Answer 3

Assuming your object only has two keys and you know the other key;

var o = {
    "PK_Column_Value": "C",
    "Column_Description": "Consumables"
};

1. get the keys

    var keys = [], k; for (k in o) keys.push(k); 

2. find Column_Description

    i = keys.indexOf('Column_Description'); 

3. get the other key

    k = keys[1 - i]; 

Now

k === 'PK_Column_Value';

This solves the fact you can't guarantee key order