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Module std.json

Implements functionality to read and write JavaScript Object Notation values.

JavaScript Object Notation is a lightweight data interchange format commonly used in web services and configuration files. It's easy for humans to read and write, and it's easy for machines to parse and generate.

Warning: While JSONValue is fine for small-scale use, at the range of hundreds of megabytes it is known to cause and exacerbate GC problems. If you encounter problems, try replacing it with a stream parser. See also



import std.conv : to;

// parse a file or string of json into a usable structure
string s = `{ "language": "D", "rating": 3.5, "code": "42" }`;
JSONValue j = parseJSON(s);
// j and j["language"] return JSONValue,
// j["language"].str returns a string
writeln(j["language"].str); // "D"
writeln(j["rating"].floating); // 3.5

// check a type
long x;
if (const(JSONValue)* code = "code" in j)
    if (code.type() == JSONType.integer)
        x = code.integer;
        x = to!int(code.str);

// create a json struct
JSONValue jj = [ "language": "D" ];
// rating doesnt exist yet, so use .object to assign
jj.object["rating"] = JSONValue(3.5);
// create an array to assign to list
jj.object["list"] = JSONValue( ["a", "b", "c"] );
// list already exists, so .object optional
jj["list"].array ~= JSONValue("D");

string jjStr = `{"language":"D","list":["a","b","c","D"],"rating":3.5}`;
writeln(jj.toString); // jjStr


parseJSON(json, maxDepth, options) Parses a serialized string and returns a tree of JSON values.
parseJSON(json, options) Parses a serialized string and returns a tree of JSON values.
toJSON() Takes a tree of JSON values and returns the serialized string.
toJSON(json, root, pretty, options)


JSONException Exception thrown on JSON errors


JSONValue JSON value node


JSONFloatLiteral String literals used to represent special float values within JSON strings.
JSONOptions Flags that control how JSON is encoded and parsed.
JSONType Enumeration of JSON types


Jeremie Pelletier, David Herberth


Boost License 1.0.