Class reference

JSON

Inherits Resource

Helper class for creating and parsing JSON data.

Description

The JSON class enables all data types to be converted to and from a JSON string. This is useful for serializing data, e.g. to save to a file or send over the network. stringify() is used to convert any data type into a JSON string. parse() is used to convert any existing JSON data into a Variant that can be used within Redot. If successfully parsed, use data to retrieve the Variant, and use @GlobalScope.typeof() to check if the Variant's type is what you expect. JSON Objects are converted into a Dictionary, but JSON data can be used to store Arrays, numbers, Strings and even just a boolean.

		var data_to_send = ["a", "b", "c"]
		var json_string = JSON.stringify(data_to_send)
		# Save data
		# ...
		# Retrieve data
		var json = JSON.new()
		var error = json.parse(json_string)
		if error == OK:
			var data_received = json.data
			if typeof(data_received) == TYPE_ARRAY:
				print(data_received) # Prints the array.
			else:
				print("Unexpected data")
		else:
			print("JSON Parse Error: ", json.get_error_message(), " in ", json_string, " at line ", json.get_error_line())

Alternatively, you can parse strings using the static parse_string() method, but it doesn't handle errors.

		var data = JSON.parse_string(json_string) # Returns null if parsing failed.

Note: Both parse methods do not fully comply with the JSON specification: - Trailing commas in arrays or objects are ignored, instead of causing a parser error. - New line and tab characters are accepted in string literals, and are treated like their corresponding escape sequences \n and \t. - Numbers are parsed using String.to_float() which is generally more lax than the JSON specification. - Certain errors, such as invalid Unicode sequences, do not cause a parser error. Instead, the string is cleaned up and an error is logged to the console.

Properties

`Variant data = null`

Contains the parsed JSON data in Variant form.

Methods

`Variant from_native(Variant variant, bool full_objects = false) static`

Converts a native engine type to a JSON-compliant value. By default, objects are ignored for security reasons, unless full_objects is true. You can convert a native value to a JSON string like this:

				func encode_data(value, full_objects = false):
					return JSON.stringify(JSON.from_native(value, full_objects))

`int get_error_line() const`

Returns 0 if the last call to parse() was successful, or the line number where the parse failed.

`String get_error_message() const`

Returns an empty string if the last call to parse() was successful, or the error message if it failed.

`String get_parsed_text() const`

Return the text parsed by parse() (requires passing keep_text to parse()).

`int parse(String json_text, bool keep_text = false)`

Attempts to parse the json_text provided. Returns an Error. If the parse was successful, it returns OK and the result can be retrieved using data. If unsuccessful, use get_error_line() and get_error_message() to identify the source of the failure. Non-static variant of parse_string(), if you want custom error handling. The optional keep_text argument instructs the parser to keep a copy of the original text. This text can be obtained later by using the get_parsed_text() function and is used when saving the resource (instead of generating new text from data).

`Variant parse_string(String json_string) static`

Attempts to parse the json_string provided and returns the parsed data. Returns null if parse failed.

`String stringify(Variant data, String indent = "", bool sort_keys = true, bool full_precision = false) static`

Converts a Variant var to JSON text and returns the result. Useful for serializing data to store or send over the network. Note: The JSON specification does not define integer or float types, but only a number type. Therefore, converting a Variant to JSON text will convert all numerical values to float types. Note: If full_precision is true, when stringifying floats, the unreliable digits are stringified in addition to the reliable digits to guarantee exact decoding. The indent parameter controls if and how something is indented; its contents will be used where there should be an indent in the output. Even spaces like " " will work. \t and \n can also be used for a tab indent, or to make a newline for each indent respectively. Example output:

				## JSON.stringify(my_dictionary)
				{"name":"my_dictionary","version":"1.0.0","entities":[{"name":"entity_0","value":"value_0"},{"name":"entity_1","value":"value_1"}]}

				## JSON.stringify(my_dictionary, "\t")
				{
					"name": "my_dictionary",
					"version": "1.0.0",
					"entities": [
						{
							"name": "entity_0",
							"value": "value_0"
						},
						{
							"name": "entity_1",
							"value": "value_1"
						}
					]
				}

				## JSON.stringify(my_dictionary, "...")
				{
				..."name": "my_dictionary",
				..."version": "1.0.0",
				..."entities": [
				......{
				........."name": "entity_0",
				........."value": "value_0"
				......},
				......{
				........."name": "entity_1",
				........."value": "value_1"
				......}
				...]
				}

`Variant to_native(Variant json, bool allow_objects = false) static`

Converts a JSON-compliant value that was created with from_native() back to native engine types. By default, objects are ignored for security reasons, unless allow_objects is true. You can convert a JSON string back to a native value like this:

				func decode_data(string, allow_objects = false):
					return JSON.to_native(JSON.parse_string(string), allow_objects)

Source revision 5592dc3a7a61