JSON module (json)

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bring json lets you build, parse, and serialize JSON data. The module provides a json::JsonNode class with a fluent API for constructing nested objects and arrays.

A tiny program

bring json

var obj: json::JsonNode = json::newObject()
obj.put("name", json::newString("FlowWing"))
obj.put("year", json::newNumber(2024))
obj.put("active", json::newBool(true))

var jsonStr: str = json::stringify(obj)
println(jsonStr)

Output:

{"name": "FlowWing", "year": 2024, "active": true}

Building JSON

Create nodes with the factory functions, then chain calls to build your structure:

Objects

bring json

var user: json::JsonNode = json::newObject()
  .put("name", json::newString("Alice"))
  .put("age", json::newNumber(30))

var address: json::JsonNode = json::newObject()
  .put("city", json::newString("New York"))
  .put("zip", json::newString("10001"))

user.put("address", address)
println(json::stringify(user))

Arrays

bring json

var arr: json::JsonNode = json::newArray()
  .push(json::newNumber(1))
  .push(json::newNumber(2))
  .push(json::newNumber(3))

println(json::stringify(arr))

/; Access by index
println("Index 1: ", arr.getAt(1).numVal)

Parsing JSON

Parse a JSON string into a JsonNode tree:

bring json

var raw: str = "{\"x\":10,\"y\":[1,2,3],\"ok\":true}"
var root: json::JsonNode = json::parse(raw)

println("x = ", root.get("x").numVal)
println("y[0] = ", root.get("y").getAt(0).numVal)

Note on string literals: Flow-Wing uses double quotes for strings. Escape inner double quotes with backslash when embedding JSON: "{\"key\":\"val\"}".

Factory functions

Function	Returns	Description
json::newObject()	json::JsonNode	Creates an empty JSON object {}
json::newArray()	json::JsonNode	Creates an empty JSON array []
json::newString(s)	json::JsonNode	Creates a JSON string node
json::newNumber(n)	json::JsonNode	Creates a JSON number node
json::newBool(b)	json::JsonNode	Creates a JSON boolean node
json::newNull()	json::JsonNode	Creates a JSON null node

Serialization & parsing

Function	Returns	Description
json::stringify(node)	str	Serializes a node to a JSON string. Strings and keys are escaped, so the result is always valid JSON
json::parse(str)	json::JsonNode	Parses a JSON string into a node tree
json::quote(s)	str	s as a JSON string literal: in quotes, with ", \ and control characters escaped

Accessing values

Property / Method	Type / Returns	Description
.strVal	str	String value of a node
.numVal	deci	Numeric value of a node
.boolVal	bool	Boolean value of a node
.get(key)	json::JsonNode	Get value by key in an object
.getAt(index)	json::JsonNode	Get item by index in an array (out-of-bounds returns null)
.put(key, val)	json::JsonNode	Set/update a key in an object (returns self)
.push(val)	json::JsonNode	Append to an array (returns self)

Supported JSON features

• Nested structures — objects inside objects, arrays inside arrays
• Method chaining — .put().put().push() style
• Key overwriting — calling .put(key, ...) on an existing key updates it
• Escaped characters — json::parse reads every JSON escape (\n, \t, \r, \b, \f, \", \\, \/, and \uXXXX, including surrogate pairs); json::stringify writes them back
• UTF-8 text — kept exactly as it is, in both directions
• Malformed JSON — json::parse() on invalid input returns an empty object {}

Source & tests (if you have the repository)

What	Where
Module source	fw-modules/json_module/json-module.fg
Integration fixtures	tests/fixtures/LatestTests/JsonModuleTests/