JSONObject

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Revision as of 19:17, 28 February 2013 by Paul Zirkle (Talk | contribs)

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Contents

Author

Matt Schoen of Defective Studios

Download

Download JSONObject.zip

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 json.org, but found them to be too complicated. 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.

As an aside, this class is pretty central to the AssetCloud content management system, from Defective Studios.

Usage

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

Sample data (in JSON format): {"field1":0.5,"field2":"sampletext","field3":[1,2,3]}

Features

  • Decode JSON-formatted strings into a usable data structure
  • Encode structured data into a JSON-formatted string
  • Interoperable with System.Collections.Generic.Dictionary
  • Copy to new JSONObject
  • Merge with another JSONObject (experimental)
  • Random access (with [int] or [string])
  • ToString() returns JSON 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 :)

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.

Note: This section used to be WRONG!

//Note: your data can only be numbers and strings.  This is not a solution for object serialization or anything like that.
JSONObject j = new JSONObject(JSONObject.Type.OBJECT);
//number
j.AddField("field1", 0.5);
//string
j.AddField("field2", "sampletext");
//array
JSONObject arr = new JSONObject(JSONObject.Type.ARRAY);
j.AddField("field3", arr);
 
arr.Add(1);
arr.Add(2);
arr.Add(3);
 
string encodedString = j.print();

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".


string encodedString = "{\"field1\":0.5,\"field2\":\"sampletext\",\"field3\":[1,2,3]}";
JSONObject j = new JSONObject(encodedString);
accessData(j);
//access data (and print it)
void accessData(JSONObject obj){
	switch(obj.type){
		case JSONObject.Type.OBJECT:
			for(int i = 0; i < obj.list.Count; i++){
				string key = (string)obj.keys[i];
				JSONObject j = (JSONObject)obj.list[i];
				Debug.Log(key);
				accessData(j);
			}
			break;
		case JSONObject.Type.ARRAY:
			foreach(JSONObject j in obj.list){
				accessData(j);
			}
			break;
		case JSONObject.Type.STRING:
			Debug.Log(obj.str);
			break;
		case JSONObject.Type.NUMBER:
			Debug.Log(obj.n);
			break;
		case JSONObject.Type.BOOL:
			Debug.Log(obj.b);
			break;
		case JSONObject.Type.NULL:
			Debug.Log("NULL");
			break;
 
	}
}

New! (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):

JSONObject arr = obj["field3"];
Debug.log(arr[2].n);		//Should ouptut "3"

The JSONObject class

#define READABLE
 
using UnityEngine;
using System.Collections;
using System.Collections.Generic;
 
/*
 * http://www.opensource.org/licenses/lgpl-2.1.php
 * JSONObject class
 * for use with Unity
 * Copyright Matt Schoen 2010
 */
 
public class JSONObject : Nullable {
	const int MAX_DEPTH = 1000;
	const string INFINITY = "\"INFINITY\"";
	const string NEGINFINITY = "\"NEGINFINITY\"";
	public enum Type { NULL, STRING, NUMBER, OBJECT, ARRAY, BOOL }
	public bool isContainer { get { return (type == Type.ARRAY || type == Type.OBJECT); }}
	public JSONObject parent;
	public Type type = Type.NULL;
	public int Count { get { return list.Count; } }
	public ArrayList list = new ArrayList();
	public ArrayList keys = new ArrayList();
	public string str;
	public double n;
	public bool b;
 
	public static JSONObject nullJO { get { return new JSONObject(JSONObject.Type.NULL); } }
	public static JSONObject obj { get { return new JSONObject(JSONObject.Type.OBJECT); } }
	public static JSONObject arr { get { return new JSONObject(JSONObject.Type.ARRAY); } }
 
	public JSONObject(JSONObject.Type t) {
		type = t;
		switch(t) {
		case Type.ARRAY:
			list = new ArrayList();
			break;
		case Type.OBJECT:
			list = new ArrayList();
			keys = new ArrayList();
			break;
		}
	}
	public JSONObject(bool b) {
		type = Type.BOOL;
		this.b = b;
	}
	public JSONObject(float f) {
		type = Type.NUMBER;
		this.n = f;
	}
	public JSONObject(Dictionary<string, string> dic) {
		type = Type.OBJECT;
		foreach(KeyValuePair<string, string> kvp in dic){
			keys.Add(kvp.Key);
			list.Add(new JSONObject { type = Type.STRING, str = kvp.Value });
		}
	}
	public void Absorb(JSONObject obj){
		list.AddRange(obj.list);
		keys.AddRange(obj.keys);
		str = obj.str;
		n = obj.n;
		b = obj.b;
		type = obj.type;
	}
	public JSONObject() { }
	public JSONObject(string str) {	//create a new JSONObject from a string (this will also create any children, and parse the whole string)
		//Debug.Log(str);
		if(str != null) {
			//TODO: fix the parsing so that i don't have to just strip out all newlines, etc.
#if(READABLE)
			str = str.Replace("\\n", "");
			str = str.Replace("\\t", "");
			str = str.Replace("\\r", "");
			str = str.Replace("\t", "");
			str = str.Replace("\r", "");
			str = str.Replace("\n", "");
			str = str.Replace("\\", "");
#endif
			if(str.Length > 0) {
				if(string.Compare(str, "true", true) == 0) {
					type = Type.BOOL;
					b = true;
				} else if(string.Compare(str, "false", true) == 0) {
					type = Type.BOOL;
					b = false;
				} else if(str == "null") {
					type = Type.NULL;
				} else if(str == INFINITY){
					type = Type.NUMBER;
					n = Mathf.Infinity;
				} else if(str == NEGINFINITY){
					type = Type.NUMBER;
					n = Mathf.NegativeInfinity;
				} else if(str[0] == '"') {
					type = Type.STRING;
					this.str = str.Substring(1, str.Length - 2);
				} else {
					try {
						n = System.Convert.ToDouble(str);
						type = Type.NUMBER;
					} catch(System.FormatException) {
						int token_tmp = 0;
						/*
						 * Checking for the following formatting (www.json.org)
						 * object - {"field1":value,"field2":value}
						 * array - [value,value,value]
						 * value - string	- "string"
						 *		 - number	- 0.0
						 *		 - bool		- true -or- false
						 *		 - null		- null
						 */
						switch(str[0]) {
						case '{':
							type = Type.OBJECT;
							keys = new ArrayList();
							list = new ArrayList();
							break;
						case '[':
							type = JSONObject.Type.ARRAY;
							list = new ArrayList();
							break;
						default:
							type = Type.NULL;
							Debug.LogWarning("improper JSON formatting:" + str);
							return;
						}
						int depth = 0;
						bool openquote = false;
						bool inProp = false;
						for(int i = 1; i < str.Length; i++) {
							if(str[i] == '\\' || str[i] == '\t' || str[i] == '\n' || str[i] == '\r') {
								i++;
								continue;
							} else if(str[i] == '"')
								openquote = !openquote;
							else if(str[i] == '[' || str[i] == '{')
								depth++;
							if(depth == 0 && !openquote) {
								if(str[i] == ':' && !inProp) {
									inProp = true;
									try {
										keys.Add(str.Substring(token_tmp + 2, i - token_tmp - 3));
									} catch { Debug.Log(i + " - " + str.Length + " - " + str); }
									token_tmp = i;
								}
								if(str[i] == ',') {
									inProp = false;
									list.Add(new JSONObject(str.Substring(token_tmp + 1, i - token_tmp - 1)));
									token_tmp = i;
								}
								if(str[i] == ']' || str[i] == '}')
									list.Add(new JSONObject(str.Substring(token_tmp + 1, i - token_tmp - 1)));
							}
							if(str[i] == ']' || str[i] == '}')
								depth--;
						}
					}
				}
			}
		} else {
			type = Type.NULL;	//If the string is missing, this is a null
		}
	}
	public void Add(bool val) { Add(new JSONObject(val)); }
	public void Add(float val) { Add(new JSONObject(val)); }
	public void Add(int val) { Add(new JSONObject(val)); }
	public void Add(JSONObject obj) {
		if(obj) {		//Don't do anything if the object is null
			if(type != JSONObject.Type.ARRAY) {
				type = JSONObject.Type.ARRAY;		//Congratulations, son, you're an ARRAY now
				Debug.LogWarning("tried to add an object to a non-array JSONObject.  We'll do it for you, but you might be doing something wrong.");
			}
			list.Add(obj);
		}
	}
	public void AddField(string name, bool val) { AddField(name, new JSONObject(val)); }
	public void AddField(string name, float val) { AddField(name, new JSONObject(val)); }
	public void AddField(string name, int val) { AddField(name, new JSONObject(val)); }
	public void AddField(string name, string val) {
		AddField(name, new JSONObject { type = JSONObject.Type.STRING, str = val });
	}
	public void AddField(string name, JSONObject obj) {
		if(obj){		//Don't do anything if the object is null
			if(type != JSONObject.Type.OBJECT){
				type = JSONObject.Type.OBJECT;		//Congratulations, son, you're an OBJECT now
				Debug.LogWarning("tried to add a field to a non-object JSONObject.  We'll do it for you, but you might be doing something wrong.");
			}
			keys.Add(name);
			list.Add(obj);
		}
	}
	public void SetField(string name, JSONObject obj) {
		if(HasField(name)) {
			list.Remove(this[name]);
			keys.Remove(name);
		}
		AddField(name, obj);
	}
	public JSONObject GetField(string name) {
		if(type == JSONObject.Type.OBJECT)
			for(int i = 0; i < keys.Count; i++)
				if((string)keys[i] == name)
					return (JSONObject)list[i];
		return null;
	}
	public bool HasField(string name) {
		if(type == JSONObject.Type.OBJECT)
			for(int i = 0; i < keys.Count; i++)
				if((string)keys[i] == name)
					return true;
		return false;
	}
	public void Clear() {
		type = JSONObject.Type.NULL;
		list.Clear();
		keys.Clear();
		str = "";
		n = 0;
		b = false;
	}
	public JSONObject Copy() {
		return new JSONObject(print());
	}
	/*
	 * The Merge function is experimental. Use at your own risk.
	 */
	public void Merge(JSONObject obj) {
		MergeRecur(this, obj);
	}
	/// <summary>
	/// Merge object right into left recursively
	/// </summary>
	/// <param name="left">The left (base) object</param>
	/// <param name="right">The right (new) object</param>
	static void MergeRecur(JSONObject left, JSONObject right) {
		if(left.type == JSONObject.Type.NULL)
			left.Absorb(right);
		else if(left.type == Type.OBJECT && right.type == Type.OBJECT) {
			for(int i = 0; i < right.list.Count; i++) {
				string key = (string)right.keys[i];
				if(right[i].isContainer){
					if(left.HasField(key))
						MergeRecur(left[key], right[i]);
					else
						left.AddField(key, right[i]);
				} else {
					if(left.HasField(key))
						left.SetField(key, right[i]);
					else
						left.AddField(key, right[i]);
				}
			}
		} else if(left.type == Type.ARRAY && right.type == Type.ARRAY) {
			if(right.Count > left.Count){
				Debug.LogError("Cannot merge arrays when right object has more elements");
				return;
			}
			for(int i = 0; i < right.list.Count; i++) {
				if(left[i].type == right[i].type) {			//Only overwrite with the same type
					if(left[i].isContainer)
						MergeRecur(left[i], right[i]);
					else{
						left[i] = right[i];
					}
				}
			}
		}
	}
	public string print() {
		return print(0);
	}
	public string print(int depth) {	//Convert the JSONObject into a stiring
		if(depth++ > MAX_DEPTH) {
			Debug.Log("reached max depth!");
			return "";
		}
		string str = "";
		switch(type) {
		case Type.STRING:
			str = "\"" + this.str + "\"";
			break;
		case Type.NUMBER:
			if(n == Mathf.Infinity)
				str = INFINITY;
			else if(n == Mathf.NegativeInfinity)
				str = NEGINFINITY;
			else
				str += n;
			break;
		case JSONObject.Type.OBJECT:
			if(list.Count > 0) {
				str = "{";
#if(READABLE)	//for a bit more readability, comment the define above to save space
				str += "\n";
				depth++;
#endif
				for(int i = 0; i < list.Count; i++) {
					string key = (string)keys[i];
					JSONObject obj = (JSONObject)list[i];
					if(obj) {
#if(READABLE)
						for(int j = 0; j < depth; j++)
							str += "\t"; //for a bit more readability
#endif
						str += "\"" + key + "\":";
						str += obj.print(depth) + ",";
#if(READABLE)
						str += "\n";
#endif
					}
				}
#if(READABLE)
				str = str.Substring(0, str.Length - 1);
#endif
				str = str.Substring(0, str.Length - 1);
				str += "}";
			} else str = "null";
			break;
		case JSONObject.Type.ARRAY:
			if(list.Count > 0) {
				str = "[";
#if(READABLE)
				str += "\n"; //for a bit more readability
				depth++;
#endif
				foreach(JSONObject obj in list) {
					if(obj) {
#if(READABLE)
						for(int j = 0; j < depth; j++)
							str += "\t"; //for a bit more readability
#endif
						str += obj.print(depth) + ",";
#if(READABLE)
						str += "\n"; //for a bit more readability
#endif
					}
				}
#if(READABLE)
				str = str.Substring(0, str.Length - 1);
#endif
				str = str.Substring(0, str.Length - 1);
				str += "]";
			} else str = "null";
			break;
		case Type.BOOL:
			if(b)
				str = "true";
			else
				str = "false";
			break;
		case Type.NULL:
			str = "null";
			break;
		}
		return str;
	}
	public JSONObject this[int index] {
		get {
			if(list.Count > index)	return (JSONObject)list[index];
			else 					return null;
		}
		set {
			if(list.Count > index)
				list[index] = value;
		}
	}
	public JSONObject this[string index] {
		get {
			return GetField(index);
		}
		set {
			SetField(index, value);
		}
	}
	public override string ToString() {
		return print();
	}
	public Dictionary<string, string> ToDictionary() {
		if(type == Type.OBJECT) {
			Dictionary<string, string> result = new Dictionary<string, string>();
			for(int i = 0; i < list.Count; i++) {
				JSONObject val = (JSONObject)list[i];
				switch(val.type){
				case Type.STRING:	result.Add((string)keys[i], val.str);		break;
				case Type.NUMBER:	result.Add((string)keys[i], val.n + "");	break;
				case Type.BOOL:		result.Add((string)keys[i], val.b + "");	break;
				default: Debug.LogWarning("Omitting object: " + (string)keys[i] + " in dictionary conversion"); break;
				}
			}
			return result;
		} else Debug.LogWarning("Tried to turn non-Object JSONObject into a dictionary");
		return null;
	}
}

The Nullable Class

You'll need to include this in your project, or remove the ": Nullable" after the class declaration. I use this class on most of the classes I create ad-hoc to allow the shorthand

if(object) { ... }
//As opposed to
if(object != null) { ... }

to check against null references.

using UnityEngine;
using System.Collections;
 
public class Nullable {
	//Extend this class if you want to use the syntax
	//	if(myObject)
	//to check if it is not null
	public static implicit operator bool(Nullable o) {
		return (object)o != null;
	}
}

Escape Characters

patch by Paul Zirkle

The original code has a bug when dealing with json objects that have string properties with escaped characters. For instance:

 { "someProperty":5, "escapedString":" \" my string has quotes \" " }

In order to support this, I have made the following patch in my version of JSONObject:

public JSONObject(string str) {	//create a new JSONObject from a string (this will also create any children, and parse the whole string)
 if(str != null) {
 #if(READABLE)
   str = str.Replace("\\n", "");
   str = str.Replace("\\t", "");
   str = str.Replace("\\r", "");
   str = str.Replace("\t", "");
   str = str.Replace("\r", "");
   str = str.Replace("\n", "");
   //PDZ str = str.Replace("\\", ""); -- dont do this here because you could be editing escaped string values not just line extentions
 #endif
   if(str.Length > 0) {
     if(string.Compare(str, "true", true) == 0) {
       type = Type.BOOL;
       b = true;
     } else if(string.Compare(str, "false", true) == 0) {
       type = Type.BOOL;
       b = false;
     } else if(str == "null") {
       type = Type.NULL;
     } else if(str == INFINITY){
       type = Type.NUMBER;
       n = Mathf.Infinity;
     } else if(str == NEGINFINITY){
       type = Type.NUMBER;
       n = Mathf.NegativeInfinity;
     } else if(str[0] == '"') {
       type = Type.STRING;
       this.str = str.Substring(1, str.Length - 2);	
       //PDZ -- unescape the string
       if( this.str.Contains("\\") )
       {
           this.str = this.str.Replace("\\\\", "\\");
           this.str = this.str.Replace("\\\"", "\"");
           this.str = this.str.Replace("\\/", "/");
       }
  }
 ... ETC ...
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