fromJson static method

Implementation

static DType fromJson(Map<String, Object?> json) {
  final kind = json['kind'];
  final simple = _simple[kind];
  if (simple != null) return simple;
  return switch (kind) {
    'decimal' => DecimalType(
      precision: json['precision'] as int,
      scale: json['scale'] as int,
    ),
    'datetime' => DateTimeType(
      TimeUnit.fromJson(json['unit'] as String),
      timeZone: json['timeZone'] as String?,
    ),
    'duration' => DurationType(TimeUnit.fromJson(json['unit'] as String)),
    'array' => ArrayType(
      fromJson((json['inner'] as Map).cast()),
      json['width'] as int,
    ),
    'list' => ListType(fromJson((json['inner'] as Map).cast())),
    'object' => ObjectType(json['label'] as String),
    'unknown' => UnknownType.fromJson(json),
    'categorical' => CategoricalType(
      name: json['name'] as String,
      namespace: json['namespace'] as String,
      hash: _parseUnsigned64(json['hash'], 'hash'),
      physical: CategoricalPhysical.fromJson(json['physical'] as String),
    ),
    'enum' => EnumType((json['categories'] as List).cast<String>()),
    'struct' => StructType(
      (json['fields'] as List).map((field) {
        final map = (field as Map).cast<String, Object?>();
        return Field(
          map['name'] as String,
          fromJson((map['dtype'] as Map).cast<String, Object?>()),
        );
      }),
    ),
    'extension' => ExtensionType(
      json['name'] as String,
      fromJson((json['storage'] as Map).cast<String, Object?>()),
      metadata: json['metadata'] as String?,
    ),
    _ => throw FormatException('Unknown Polars datatype kind: $kind'),
  };
}