How do I make a JSON object with multiple arrays?
JsonJson Problem Overview
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.
Json Solutions
Solution 1 - Json
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:
Solution 2 - Json
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.
Solution 3 - Json
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":"júuna",
"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
$.each(data[0], function(i, item) {
data[0][i].deviceId + data[0][i].typeOfDevice + data[0][i].state + data[0][i].assigned
});
Use http://www.jsoneditoronline.org/ to understand the JSON code better
Solution 4 - Json
var cars = [
manufacturer: [
{
color: 'gray',
model: '1',
nOfDoors: 4
},
{
color: 'yellow',
model: '2',
nOfDoors: 4
}
]
]
Solution 5 - Json
Using the below method pass any value which is an array:
Use:
<dependency>
<groupId>com.jayway.jsonpath</groupId>
<artifactId>json-path</artifactId>
<version>2.5.0</version>
</dependency>
Input parameter: URL, like
Example: "$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;
}