Author

Matt Schoen [email protected] of Defective Studios

Intro

I came across the need to send structured data to and from a server on one of my projects, and figured it would be worth my while to use JSON. When I looked into the issue, I tried a few of the C# implementations listed on http://json.org, but found them to be too complicated to work with and expand upon. So, I've written a very simple JSONObject class, which can be generically used to encode/decode data into a simple container. This page assumes that you know what JSON is, and how it works. It's rather simple, just go to json.org for a visual description of the encoding format.

Usage

Users should not have to modify the JSONObject class themselves, and must follow the very simple procedures outlined below:

Sample data (in JSON format):

{
    "TestObject": {
        "SomeText": "Blah",
        "SomeObject": {
            "SomeNumber": 42,
            "SomeBool": true,
            "SomeNull": null
        },
        
        "SomeEmptyObject": { },
        "SomeEmptyArray": [ ],
        "EmbeddedObject": "{\"field\":\"Value with \\\"escaped quotes\\\"\"}"
    }
}

The test classes provide the best examples for how the API is intended to be used.

Features

• Decode JSON-formatted strings into a usable data structure
• Encode structured data into a JSON-formatted string
• Interoperable with Dictionary and WWWForm
• Optimized parse/stringify functions -- minimal (unavoidable) garbage creation
• Asynchronous stringify function for serializing lots of data without frame drops
• MaxDepth parsing will skip over nested data that you don't need
• Special (non-compliant) Baked object type can store stringified data within parsed objects
• Copy to new JSONObject
• Merge with another JSONObject (experimental)
• Random access (with int or string)
• ToString() returns JSON data with optional "pretty" flag to include newlines and tabs
• Switch between double and float for numeric storage depending on level of precision needed (and to ensure that numbers are parsed/stringified correctly)
• Supports Infinity and NaN values
• JSONTemplates static class provides serialization functions for common classes like Vector3, Matrix4x4
• Object pool implementation (experimental)
• Handy JSONChecker window to test parsing on sample data

It should be pretty obvious what this parser can and cannot do. If anyone reading this is a JSON buff (is there such a thing?) please feel free to expand and modify the parser to be more compliant. Currently I am using the .NET System.Convert namespace functions for parsing the data itself. It parses strings and numbers, which was all that I needed of it, but unless the formatting is supported by System.Convert, it may not incorporate all proper JSON strings. Also, having never written a JSON parser before, I don't doubt that I could improve the efficiency or correctness of the parser. It serves my purpose, and hopefully will help you with your project! Let me know if you make any improvements :)

Also, you JSON buffs (really, who would admit to being a JSON buff...) might also notice from my feature list that this thing isn't exactly to specifications. Here is where it differs:

• "a string" is considered valid JSON. There is an optional "strict" parameter to the parser which will bomb out on such input, in case that matters to you.
• The Baked mode is totally made up.
• The MaxDepth parsing is totally made up.
• NaN and Infinity were introduced in a later version of the standard, and some linters will report them as errors

Encoding

Encoding is something of a hard-coded process. This is because I have no idea what your data is! It would be great if this were some sort of interface for taking an entire class and encoding it's number/string fields, but it's not. I've come up with a few clever ways of using loops and/or recursive methods to cut down of the amount of code I have to write when I use this tool, but they're pretty project-specific.

The constructor, Add, and AddField functions now support a nested delegate structure. This is useful if you need to create a nested JSONObject in a single line. For example:

void DoRequest(string url, string jsonString) {
	// Web Request logic
}

void Test(string url) {
	DoRequest(url, new JSONObject(request => {
		request.AddField("sort", sort => sort.AddField("_timestamp", "desc"));
		request.AddField("query", new JSONObject(query => query.AddField("match_all", JSONObject.emptyObject)));
		request.AddField("fields", fields => fields.Add("_timestamp"));
	}).ToString());
}

Decoding

Decoding is much simpler on the input end, and again, what you do with the JSONObject will vary on a per-project basis. One of the more complicated way to extract the data is with a recursive function, as drafted below. Calling the constructor with a properly formatted JSON string will return the root object (or array) containing all of its children, in one neat reference! The data is in a public ArrayList called list, with a matching key list (called keys!) if the root is an Object. If that's confusing, take a glance over the following code and the print() method in the JSONObject class. If there is an error in the JSON formatting (or if there's an error with my code!) the debug console will read "improper JSON formatting".

void Test() {
	var encodedString = "{\"field1\": 0.5,\"field2\": \"sampletext\",\"field3\": [1,2,3]}";
	var jsonObject = new JSONObject(encodedString);
	AccessData(jsonObject);
}

void AccessData(JSONObject jsonObject) {
	switch (jsonObject.type) {
		case JSONObject.Type.Object:
			for (var i = 0; i < jsonObject.list.Count; i++) {
				var key = jsonObject.keys[i];
				var value = jsonObject.list[i];
				Debug.Log(key);
				AccessData(value);
			}
			break;
		case JSONObject.Type.Array:
			foreach (JSONObject element in jsonObject.list) {
				AccessData(element);
			}
			break;
		case JSONObject.Type.String:
			Debug.Log(jsonObject.stringValue);
			break;
		case JSONObject.Type.Number:
			Debug.Log(jsonObject.floatValue);
			break;
		case JSONObject.Type.Bool:
			Debug.Log(jsonObject.boolValue);
			break;
		case JSONObject.Type.Null:
			Debug.Log("Null");
			break;
		case JSONObject.Type.Baked:
			Debug.Log(jsonObject.stringValue);
			break;
	}
}

Decoding also supports a delegate format which will automatically check if a field exists before processing the data, providing an optional parameter for an OnFieldNotFound response. For example:

void Test(string jsonString) {
	var list = new JSONObject(jsonString);
	list.GetField("users", users => {
		foreach (var user in users.list) {
			var thisUser = user;
			users.GetField("sessions", sessions => {
				foreach (JSONObject gameSession in sessions.list) {
					Debug.Log(gameSession);
				}
			}, name => Debug.LogWarning(string.Format("No sessions for user {0}", thisUser["name"].stringValue)));
		}
		
	});
}

(O(n)) Random access

I've added a string and int [] index to the class, so you can now retrieve data as such (from above):

void Test() {
	var jsonObject = new JSONObject("{\"field\":[0,1,2]");
	var array = jsonObject["field"];
	Debug.Log(array[2].intValue); //Should output "2"
}

Change Log

v2.1.3

• Fix exception where input is just an empty array or object
• Pool and null out list and keys field when clearing JSONObject for consistency with a fresh object; This was causing the MaxDepthWithExcessLevels test to fail randomly when checking results because some pooled objects had list but not keys
• Update JSONChecker with information about pools and a note about not validating standard JSON

v2.1.2

• Fix issue parsing json strings with whitespace after colon characters

v2.1.1

• Fix issue parsing nested arrays with multiple elements
• Refactor MaxDepth tests
• Fix issues with MaxDepth

v2.1

• Add async parsing method
• Rewrite and optimize parser
• Fix parsing errors
• Refactor VectorTemplates to use extension methods
• Add more tests

v2.0

• Add JSONObject to Defective.JSON namespace
• Update APIs to be more descriptive
• Fix parsing errors
• Add tests

v1.4

Big update!

• Better GC performance. Enough of that garbage!
  • Remaining culprits are internal garbage from StringBuilder.Append/AppendFormat, String.Substring, List.Add/GrowIfNeeded, Single.ToString
• Added asynchronous Stringify function for serializing large amounts of data at runtime without frame drops
• Added Baked type
• Added MaxDepth to parsing function
• Various cleanup refactors recommended by ReSharper

v1.3.2

• Added support for NaN
• Added strict mode to fail on purpose for improper formatting. Right now this just means that if the parse string doesn't start with [ or {, it will print a warning and return a null JSONObject.
• Changed infinity and NaN implementation to use float and double instead of Mathf
• Handles empty objects/arrays better
• Added a flag to print and ToString to turn on/off pretty print. The define on top is now an override to system-wide disable