Proper way of writing an external JSON file

Question

I am confused by reading a lot of JSON tutorials on the Internet (even on STO) and not able to decide what is right and what is wrong related to writing an external JSON file.

I have seen so many instances e.g.

(for a single object tho Adobe Dreamweaver CS5.5 shows syntax error, don't know why)

#1

{
    "name" : "Sachin", 
    "age" : 30,
    "country" : "India"
}

#2

For multiple objects:

[
    {
        "name" : "Sachin", 
        "age" : 30,
        "country" : "India"
    },
    {
        "name" : "Amit", 
        "age" : 28,
        "country" : "USA"
    }
]

#3

Some have been seen using single quotes around the objects array and storing the array in a variable like this:

customers = '[
                {
                    "name" : "Sachin", 
                    "age" : 30,
                    "country" : "India"
                },
                {
                    "name" : "Amit", 
                    "age" : 28,
                    "country" : "USA"
                }
            ]'

#4

A few of them writing above code in the following style:

{
    "customers" : [
                    {
                        "name" : "Sachin", 
                        "age" : 30,
                        "country" : "India"
                    },
                    {
                        "name" : "Amit", 
                        "age" : 28,
                        "country" : "USA"
                    }
                  ]
}

#5

One more extra sample format added:

{
    [
        {
            "name" : "Sachin", 
            "age" : 30,
            "country" : "India"
        },
        {
            "name" : "Amit", 
            "age" : 28,
            "country" : "USA"
        }
    ]
}

To be honest, I am totally confused and can't figure out which one is correct and standard style for writing an external .json file (especially those having multiple objects).

So I am asking all my questions here:

• What is the difference between all above formats? Using single quotes, storing the data in a variable or assigning a key to whole data etc.
• How should I compose a correct formatted .json file which can easily be read by JavaScript and PHP?
• In which standard format, the third parties APIs present json data?

Answer 1

What is the difference between all above formats? Using single quotes, storing the data in a variable or assigning a key to whole data etc.

You can't use variables in a JSON-file. The third example is probably some snippet of JSON being assigned to a variable within some application.

How should I compose a correct formatted .json file which can easily be read by JavaScript and PHP?

You can start and end the file with square brackets ([ ... ]) if you want to specify an array of multiple objects. If you start and end the file with curly brackets ({ ... }), you specify one top-level object (without a key).

However, you can embed arrays in objects, or include layers of objects. So your last example is indeed valid JSON. Read it as: a top level object, that itself has one attribute 'customers', which contains an array of more objects.

Answer 2

As per its name: JSON = JavaScript Object Notation.

It deals with only 2 things:

1. Javascript object(s) with any functions stripped out. An object can contain one or more name: value pairs, comma separated. Hopefully you can see that an object is denoted by the presence of { ... }

The JSON definition calls these name/value pairs 'members'. A member name has a colon after the name, so it can be represented as:

{ "name": value }

Value can be any basic javascript type, which are basically object, string, boolean, null OR an array. The safest way to do this so that's maximally interoperable/interchangeable is to always enclose the name in quotes, but it's not strictly necessary to be acceptable json.

So with several properties:

{
   "name": "Bob",
   "age": 3,
   "likes": ["eggs", "ham"],
   "parents": [{ "name": "Wilma"}, {"name": "Fred"],
   "deleted": false
}

2. Javascript array

An array is an ordered (ie. 0..n) list of valid json types.

[ 3, "Hello", { "firstname": "Joe", "lastname": "Dimaggio" }, [ 0, 1, 2], true ]

In javascript, you can enclose a string using either single quotes or double quotes, but in json you must always use double quotes.

This won't pass json validation:

{ "name": 'Homer' }

That is all there is to it. An object has a name and a value that could be anything including another object or an array.

Objects are denoted with {} and arrays are denoted with []

Reading a static file is another issue entirely.

With PHP you use json_decode(). That's simple other than whether you want json objects to be turned into php objects, or nested associative arrays where the javascript object property names become the keys of the array. It defaults to making objects, and frequently that's more complicated than an array.

With Javascript often people just want to use the data easily, with the various issues and workarounds illustrated in the linked question.