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This module contains procs for serialization and deserialization of arbitrary Nim data structures. The serialization format uses JSON.

Restriction: For objects, their type is not serialized. This means essentially that it does not work if the object has some other runtime type than its compiletime type.

Basic usage

Example:

import std/marshal
type
  A = object of RootObj
  B = object of A
    f: int

let a: ref A = new(B)
assert $$a[] == "{}" # not "{f: 0}"

# unmarshal
let c = to[B]("""{"f": 2}""")
assert typeof(c) is B
assert c.f == 2

# marshal
assert $$c == """{"f": 2}"""

Note: The to and $$ operations are available at compile-time!

Imports

streams, typeinfo, json, intsets, tables, unicode

Procs

proc `$$`[T](x: sink T): string: Returns a string representation of x (serialization, marshalling).

Note: to serialize x to JSON use %x from the json module or jsonutils.toJson(x).

Example:

type Foo = object id: int bar: string let x = Foo(id: 1, bar: "baz") ## serialize: let y = $$x assert y == """{"id": 1, "bar": "baz"}"""
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proc load[T](s: Stream; data: var T): Loads data from the stream s. Raises IOError in case of an error.
Example:

import std/streams var s = newStringStream("[1, 3, 5]") var a: array[3, int] load(s, a) assert a == [1, 3, 5]
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proc store[T](s: Stream; data: sink T): Stores data into the stream s. Raises IOError in case of an error.
Example:

import std/streams var s = newStringStream("") var a = [1, 3, 5] store(s, a) s.setPosition(0) assert s.readAll() == "[1, 3, 5]"
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proc to[T](data: string): T: Reads data and transforms it to a type T (deserialization, unmarshalling).
Example:

type Foo = object id: int bar: string let y = """{"id": 1, "bar": "baz"}""" assert typeof(y) is string ## deserialize to type 'Foo': let z = y.to[:Foo] assert typeof(z) is Foo assert z.id == 1 assert z.bar == "baz"
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std/marshal

Basic usage

See also

Imports

Procs