How to create nested object dynamically?

Question

I need to create an object in this format by using JavaScript.

var results = {
    "A-1": [
        { "object": "daily", "type": "when", "field": "Period" }
    ],
    "A-2": [
        { "object": "weekly", "type": "when", "field": "Period" }
    ],
    "A-3": [
        { "object": "monthly", "type": "when", "field": "Period" }
    ],
    "B-1": [
        { "object": "Boston", "type": "who", "field": "City" },
        { "object": "AG", "type": "what", "field": "region" },
        { "object": "L1", "type": "where", "field": "Level" }
    ],
    "B-2": [
        { "object": "New York", "type": "who", "field": "City" },
        { "object": "AG", "type": "what", "field": "region" },
        { "object": "L2", "type": "where", "field": "Level" }
    ],
    "B-3": [
        { "object": "Paris", "type": "who", "field": "City" },
        { "object": "EURO", "type": "what", "field": "region" },
        { "object": "L1", "type": "where", "field": "Level" }
    ],
    "B-4": [
        { "object": "Boston", "type": "who", "field": "City" },
        { "object": "AG", "type": "what", "field": "region" },
        { "object": "L2", "type": "where", "field": "Level" }
    ]
};

var periodList = "daily,weekly,monthly";

The B- section key values are returned from web services in JSON format as shown below:

 [
    { "object": "Boston", "level": "L1", "region": "AG" },
    { "object": "Paris", "level": "L1", "region": "EURO" },
    { "object": "Boston", "level": "L2", "region": "AG" },
    { "object": "China", "level": "L1", "region": "AP" },
    { "object": "New York", "level": "L2", "region": "AG" }
]

Each B- object contains the city, region and level arrays.

Please help how to create this structure dynamically?

Should China be in your desired JSON output? Also, is key ojbect in the web service returned JSON a typo in your question? — Mark A. Fitzgerald
– Mark A. Fitzgerald, Commented May 5, 2016 at 20:31
Sorry, it is typo in my returned data while I create this sample data. — Monica
– Monica, Commented May 5, 2016 at 20:53
China is just another sample data. If added, another B-5 list should be created. Thank you for your help. — Monica
– Monica, Commented May 5, 2016 at 21:31
Thanks for the the clarifications. Are the A- key-array pairs constant? — Mark A. Fitzgerald
– Mark A. Fitzgerald, Commented May 5, 2016 at 22:23
The A- key-values pairs are constant for "type" and "field". The "object" values are from a constant string of "daily,weekly,monthly". — Monica
– Monica, Commented May 5, 2016 at 22:44

Bergi · Accepted Answer · 2016-05-06 02:36:32Z

2

Just use two simple loops:

var results = {};
var periods = periodList.split(",");
for (var i=0; i<periods.length; i++)
    results["A-"+(i+1)] = [
        {"object": periods[i],    "type": "when",   "field": "Period"}
    ];
for (var i=0; i<json.length; i++)
    results["B-"+(i+1)] = [
        {"object": json[i].object, "type": "who",   "field": "City"},
        {"object": json[i].region, "type": "what",  "field": "region"},
        {"object": json[i].level,  "type": "where", "field": "Level"}
    ];

There is no arbitrary nesting, so you don't need recursion or anything heavy.

edited May 6, 2016 at 2:36

user663031

answered May 6, 2016 at 0:04

Bergi

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3 Comments

Daniel Kucal Over a year ago

periods.lenght one more typo

Monica Over a year ago

Thank you for your quick solution. I am much appreciated.

Monica Over a year ago

Hi, What if I need to add the section A to each of B section instead? How can I show my new format?

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