How do I make a JSON object with multiple arrays?

I've never used JSON before so I'm not familiar with its syntax.

At the moment I have multiple arrays containing different pieces of data.

I would like to create one JSON object, that contains the multiple arrays each with several pieces of data.

E.g.

An object called cars, containing multiple arrays each for a different make of car. In each array would be the model of car along with some other types of data e.g. number of doors (doesn't really matter its just a fictional example.)

It would be greatly appreciated if someone explained the syntax with an example.

5 Answers

On the outermost level, a JSON object starts with a { and end with a }.

Sample data:

{ "cars": { "Nissan": [ {"model":"Sentra", "doors":4}, {"model":"Maxima", "doors":4}, {"model":"Skyline", "doors":2} ], "Ford": [ {"model":"Taurus", "doors":4}, {"model":"Escort", "doors":4} ] } }

If the JSON is assigned to a variable called data, then accessing it would be like the following:

data.cars['Nissan'][0].model // Sentra data.cars['Nissan'][1].model // Maxima data.cars['Nissan'][2].doors // 2 for (var make in data.cars) { for (var i = 0; i < data.cars[make].length; i++) { var model = data.cars[make][i].model; var doors = data.cars[make][i].doors; alert(make + ', ' + model + ', ' + doors); } }

Another approach (using an associative array for car models rather than an indexed array):

{ "cars": { "Nissan": { "Sentra": {"doors":4, "transmission":"automatic"}, "Maxima": {"doors":4, "transmission":"automatic"} }, "Ford": { "Taurus": {"doors":4, "transmission":"automatic"}, "Escort": {"doors":4, "transmission":"automatic"} } } } data.cars['Nissan']['Sentra'].doors // 4 data.cars['Nissan']['Maxima'].doors // 4 data.cars['Nissan']['Maxima'].transmission // automatic for (var make in data.cars) { for (var model in data.cars[make]) { var doors = data.cars[make][model].doors; alert(make + ', ' + model + ', ' + doors); } }

Edit:

Correction: A JSON object starts with { and ends with }, but it's also valid to have a JSON array (on the outermost level), that starts with [ and ends with ].

Also, significant syntax errors in the original JSON data have been corrected: All key names in a JSON object must be in double quotes, and all string values in a JSON object or a JSON array must be in double quotes as well.

See:

A good book I'm reading: Professional JavaScript for Web Developers by Nicholas C. Zakas 3rd Edition has the following information regarding JSON Syntax:

"JSON Syntax allows the representation of three types of values".

Regarding the one you're interested in, Arrays it says:

"Arrays are represented in JSON using array literal notation from JavaScript. For example, this is an array in JavaScript:

var values = [25, "hi", true];

You can represent this same array in JSON using a similar syntax:

[25, "hi", true]

Note the absence of a variable or a semicolon. Arrays and objects can be used together to represent more complex collections of data, such as:

{ "books": [ { "title": "Professional JavaScript", "authors": [ "Nicholas C. Zakas" ], "edition": 3, "year": 2011 }, { "title": "Professional JavaScript", "authors": [ "Nicholas C.Zakas" ], "edition": 2, "year": 2009 }, { "title": "Professional Ajax", "authors": [ "Nicholas C. Zakas", "Jeremy McPeak", "Joe Fawcett" ], "edition": 2, "year": 2008 } ] }

This Array contains a number of objects representing books, Each object has several keys, one of which is "authors", which is another array. Objects and arrays are typically top-level parts of a JSON data structure (even though this is not required) and can be used to create a large number of data structures."

To serialize (convert) a JavaScript object into a JSON string you can use the JSON object stringify() method. For the example from Mark Linus answer:

var cars = [{ color: 'gray', model: '1', nOfDoors: 4 }, { color: 'yellow', model: '2', nOfDoors: 4 }];

cars is now a JavaScript object. To convert it into a JSON object you could do:

var jsonCars = JSON.stringify(cars);

Which yields:

"[{"color":"gray","model":"1","nOfDoors":4},{"color":"yellow","model":"2","nOfDoors":4}]"

To do the opposite, convert a JSON object into a JavaScript object (this is called parsing), you would use the parse() method. Search for those terms if you need more information... or get the book, it has many examples.

Another example:

[ [ { "@id":1, "deviceId":1, "typeOfDevice":"1", "state":"1", "assigned":true }, { "@id":2, "deviceId":3, "typeOfDevice":"3", "state":"Excelent", "assigned":true }, { "@id":3, "deviceId":4, "typeOfDevice":"jÃºuna", "state":"Excelent", "assigned":true }, { "@id":4, "deviceId":5, "typeOfDevice":"nffjnff", "state":"Regular", "assigned":true }, { "@id":5, "deviceId":6, "typeOfDevice":"44", "state":"Excelent", "assigned":true }, { "@id":6, "deviceId":7, "typeOfDevice":"rr", "state":"Excelent", "assigned":true }, { "@id":7, "deviceId":8, "typeOfDevice":"j", "state":"Excelent", "assigned":true }, { "@id":8, "deviceId":9, "typeOfDevice":"55", "state":"Excelent", "assigned":true }, { "@id":9, "deviceId":10, "typeOfDevice":"5", "state":"Excelent", "assigned":true }, { "@id":10, "deviceId":11, "typeOfDevice":"5", "state":"Excelent", "assigned":true } ], 1 ]

Read the array's

$.each(data[0], function(i, item) { data[0][i].deviceId + data[0][i].typeOfDevice + data[0][i].state + data[0][i].assigned });

Use to understand the JSON code better

var cars = [ manufacturer: [ { color: 'gray', model: '1', nOfDoors: 4 }, { color: 'yellow', model: '2', nOfDoors: 4 } ] ]

Using the below method pass any value which is an array: Use: <dependency> <groupId>com.jayway.jsonpath</groupId> <artifactId>json-path</artifactId> <version>2.5.0</version> </dependency> Input parameter: URL, like Example: "$node.[any int value of array].anyKeyWhichInArray" Example: "$.cars.Nissan.[0].model" public String getAnyValueFromResponseBody(String jsonBody, String url) { String value = ""; try { value = JsonPath.read(jsonBody, url).toString(); System.out.println(value); } catch (Exception var6) { System.error.println("unable to parse "+url); } return value; }