JSON and binary data - encoding

Question

I am relatively new to JSON. I have recently added JQuery and JavaScript to an application to make it more interactive and quicker. I understand how JSON works for basic types like: Strings, Numbers etc where there is a MAP i.e. a key and a value. For example: http://www.w3schools.com/json/. Here there is an Employees list, where each employee has two keys i.e. first name and last name and two values i.e. first name value and last name value.

However, I do not understand how binary data fits into the equation. Say I was to add a new property to the Employee object called: Video, which is a type: application/octet-stream like in the question: Binary Data in JSON String. Something better than Base64 and the value was:

TWFuIGlzIGRpc3Rpbmd1aXNoZWQsIG5vdCBvbmx5IGJ5IGhpcyByZWFzb24sIGJ1dCBieSB0aGlz
    IHNpbmd1bGFyIHBhc3Npb24gZnJvbSBvdGhlciBhbmltYWxzLCB3aGljaCBpcyBhIGx1c3Qgb2Yg
    dGhlIG1pbmQsIHRoYXQgYnkgYSBwZXJzZXZlcmFuY2Ugb2YgZGVsaWdodCBpbiB0aGUgY29udGlu
    dWVkIGFuZCBpbmRlZmF0aWdhYmxlIGdlbmVyYXRpb24gb2Yga25vd2xlZGdlLCBleGNlZWRzIHRo
    ZSBzaG9ydCB2ZWhlbWVuY2Ugb2YgYW55IGNhcm5hbCBwbGVhc3VyZS4=

How is this data represented as a MAP? I realise this is probably a simple question, however I do have a JSON book but it does not go into that much detail. I have not found an answer on the web either.

This data is supposed to go in a string, not in a map. However, I don't think it's a good idea to encode a video in JSON, rather just put a link to it in the JSON and load it separately. — Bergi, Aug 31 '14 at 11:29
@Bergi, are you saying that you can put anything you want into a JSON string i.e. it does not have to be in the format of: { "data" : { "field1" : "value1", "field2" : "value2"}} — w0051977, Aug 31 '14 at 11:33
@w0051977 what he means it that you put it as a string value of a json property. Like `{"video": "TWFuIGlzIGRpc3Rpbmd1aXNoZWQsIG5vdCBvbmx5IGJ5IGhpcyByZWFzb24sIGJ1dCBieSB0aGlzIHNpbmd1bGFyIHBhc3Npb24gZnJvbSBvdGhlciBhbmltYWxzLCB3aGljaCBpcyBhIGx1c3Qgb2YgdGhlIG1pbmQsIHRoYXQgYnkgYSBwZXJzZXZlcmFuY2Ugb2YgZGVsaWdodCBpbiB0aGUgY29udGludWVkIGFuZCBpbmRlZmF0aWdhYmxlIGdlbmVyYXRpb24gb2Yga25vd2xlZGdlLCBleGNlZWRzIHRoZSBzaG9ydCB2ZWhlbWVuY2Ugb2YgYW55IGNhcm5hbCBwbGVhc3VyZS4="}` — soulcheck, Aug 31 '14 at 11:34
No, by "string" I did not mean the whole "JSON string" but *a string in the JSON*, such as `"value1"` or `"value2"` in your example — Bergi, Aug 31 '14 at 11:35
@souldcheck, of course. Thanks for that. Do you have to use key value pairs for JSON? I cannot see the key in this example: http://stackoverflow.com/questions/1443158/binary-data-in-json-string-something-better-than-base64. — w0051977, Aug 31 '14 at 11:35

score 0 · Accepted Answer · edited May 23 '17 at 12:06

I think you are giving "maps" (KV pairs) too much value. As you've pointed out, JSON has a small number of types: numbers, strings, true and false, null, arrays, and objects. You can think of objects and "maps" as being the same thing. Objects can be built up of the other types, for example:

{
    "person": {
        "name": "John"
    }
}

Person is an object that has a name property that is a string.

So, if you want to represent binary data in JSON, you will have to use one of the existing types (usually as a string via Base64). In the example given in the linked question, the value property of the object is the Base64-encoded value of the file.

{
    "mimetype" : "application/octet-stream”,
    "metadata" : [ ],
    "value" :   "TWFuIGlzIGRpc3Rpbmd1aXNoZWQsIG5vdCBvbmx5IGJ5IGhpcyByZWFzb24sIGJ1dCBieSB0aGlzIHNpbmd1bGFyIHBhc3Npb24gZnJvbSBvdGhlciBhbmltYWxzLCB3aGljaCBpcyBhIGx1c3Qgb2YgdGhlIG1pbmQsIHRoYXQgYnkgYSBwZXJzZXZlcmFuY2Ugb2YgZGVsaWdodCBpbiB0aGUgY29udGludWVkIGFuZCBpbmRlZmF0aWdhYmxlIGdlbmVyYXRpb24gb2Yga25vd2xlZGdlLCBleGNlZWRzIHRoZSBzaG9ydCB2ZWhlbWVuY2Ugb2YgYW55IGNhcm5hbCBwbGVhc3VyZS4=",
}

If you are familiar with JavaScript, the following would give you the Base64-encoded value as a string:

var obj = JSON.parse(json);
var value = obj.value; // This is a string

Thanks but what is the key in the above example? I understand the value is the binary data. — w0051977, Aug 31 '14 at 15:30
The key would be `value` and it's value would be a string, not binary. — Whymarrh, Aug 31 '14 at 17:16

JSON and binary data - encoding

1 Answers1