This module implements a hookable (de)serialization for arbitrary types. Design goal: avoid importing modules where a custom serialization is needed; see strtabs.fromJsonHook,toJsonHook for an example.
Example:
import std/jsonutils import std/[strtabs,json] type Foo = ref object t: bool z1: int8 let a = (1.5'f32, (b: "b2", a: "a2"), 'x', @[Foo(t: true, z1: -3), nil], [{"name": "John"}.newStringTable]) let j = a.toJson assert j.jsonTo(typeof(a)).toJson == j assert $[NaN, Inf, -Inf, 0.0, -0.0, 1.0, 1e-2].toJson == """["nan","inf","-inf",0.0,-0.0,1.0,0.01]""" assert 0.0.toJson.kind == JFloat assert Inf.toJson.kind == JString
Types
Joptions = object allowExtraKeys*: bool ## If `true` Nim's object to which the JSON is parsed is not required to ## have a field for every JSON key. allowMissingKeys*: bool ## If `true` Nim's object to which JSON is parsed is allowed to have ## fields without corresponding JSON keys.
- Options controlling the behavior of fromJson. Source Edit
JsonNodeMode = enum joptJsonNodeAsRef, ## returns the ref as is joptJsonNodeAsCopy, ## returns a deep copy of the JsonNode joptJsonNodeAsObject ## treats JsonNode as a regular ref object
- controls toJson for JsonNode types Source Edit
ToJsonOptions = object enumMode*: EnumMode jsonNodeMode*: JsonNodeMode
- Source Edit
Procs
proc fromJsonHook(a: var StringTableRef; b: JsonNode) {. ...raises: [KeyError, ValueError, JsonKindError], tags: [].}
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Enables fromJson for StringTableRef type.
See also:
Example:
import std/[strtabs, json] var t = newStringTable(modeCaseSensitive) let jsonStr = """{"mode": 0, "table": {"name": "John", "surname": "Doe"}}""" fromJsonHook(t, parseJson(jsonStr)) assert t[] == newStringTable("name", "John", "surname", "Doe", modeCaseSensitive)[]
Source Edit proc fromJsonHook[A](s: var SomeSet[A]; jsonNode: JsonNode)
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Enables fromJson for HashSet and OrderedSet types.
See also:
Example:
import std/[sets, json] var foo: tuple[hs: HashSet[string], os: OrderedSet[string]] fromJson(foo, parseJson(""" {"hs": ["hash", "set"], "os": ["ordered", "set"]}""")) assert foo.hs == ["hash", "set"].toHashSet assert foo.os == ["ordered", "set"].toOrderedSet
Source Edit proc fromJsonHook[K: string | cstring; V]( t: var (Table[K, V] | OrderedTable[K, V]); jsonNode: JsonNode)
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Enables fromJson for Table and OrderedTable types.
See also:
Example:
import std/[tables, json] var foo: tuple[t: Table[string, int], ot: OrderedTable[string, int]] fromJson(foo, parseJson(""" {"t":{"two":2,"one":1},"ot":{"one":1,"three":3}}""")) assert foo.t == [("one", 1), ("two", 2)].toTable assert foo.ot == [("one", 1), ("three", 3)].toOrderedTable
Source Edit proc fromJsonHook[T](self: var Option[T]; jsonNode: JsonNode)
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Enables fromJson for Option types.
See also:
Example:
import std/[options, json] var opt: Option[string] fromJsonHook(opt, parseJson("\"test\"")) assert get(opt) == "test" fromJson(opt, parseJson("null")) assert isNone(opt)
Source Edit proc initToJsonOptions(): ToJsonOptions {....raises: [], tags: [].}
- initializes ToJsonOptions with sane options. Source Edit
proc toJson[T](a: T; opt = initToJsonOptions()): JsonNode
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serializes a to json; uses toJsonHook(a: T) if it's in scope to customize serialization, see strtabs.toJsonHook for an example.Note: With -d:nimPreviewJsonutilsHoleyEnum, toJson now can serialize/deserialize holey enums as regular enums (via ord) instead of as strings. It is expected that this behavior becomes the new default in upcoming versions.Source Edit
proc toJsonHook(a: StringTableRef): JsonNode {....raises: [], tags: [].}
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Enables toJson for StringTableRef type.
See also:
Example:
import std/[strtabs, json] let t = newStringTable("name", "John", "surname", "Doe", modeCaseSensitive) let jsonStr = """{"mode": "modeCaseSensitive", "table": {"name": "John", "surname": "Doe"}}""" assert toJson(t) == parseJson(jsonStr)
Source Edit proc toJsonHook[A](s: SomeSet[A]): JsonNode
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Enables toJson for HashSet and OrderedSet types.
See also:
Example:
import std/[sets, json] let foo = (hs: ["hash"].toHashSet, os: ["ordered", "set"].toOrderedSet) assert $toJson(foo) == """{"hs":["hash"],"os":["ordered","set"]}"""
Source Edit proc toJsonHook[K: string | cstring; V](t: (Table[K, V] | OrderedTable[K, V])): JsonNode
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Enables toJson for Table and OrderedTable types.
See also:
Example:
import std/[tables, json, sugar] let foo = ( t: [("two", 2)].toTable, ot: [("one", 1), ("three", 3)].toOrderedTable) assert $toJson(foo) == """{"t":{"two":2},"ot":{"one":1,"three":3}}""" # if keys are not string|cstring, you can use this: let a = {10: "foo", 11: "bar"}.newOrderedTable let a2 = collect: (for k,v in a: (k,v)) assert $toJson(a2) == """[[10,"foo"],[11,"bar"]]"""
Source Edit proc toJsonHook[T](self: Option[T]): JsonNode
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Enables toJson for Option types.
See also:
Example:
import std/[options, json] let optSome = some("test") assert $toJson(optSome) == "\"test\"" let optNone = none[string]() assert $toJson(optNone) == "null"
Source Edit