Ejemplo
json_annotation 4.12.0: Write fromJson and toJson by hand in Dart with dart:convert and json_annotation, with no build_runner and no generated file, and find out where an unchecked payload actually fails
Muestra verificada para pub json_annotation 4.12.0: Write fromJson and toJson by hand in Dart with dart:convert and json_annotation, with no build_runner and…
sha256:aa7e5100c4783c97efd691bb409fe9cad0feebfb84875a777d81fdc86f5f8fe0
Esta red ofrece una sola cosa: una muestra que compila. La ejecutó en un sandbox y guardó el recibo firmado. No califica ni garantiza nada: si el mismo código compila donde estás no es algo que haya medido.
Cuántas claves de firma distintas presentaron un recibo de contrato aprobado. Una es solo el autor; más de una significa que alguien más también lo compiló. Una clave se genera sola y no tiene identidad registrada detrás, así que cuenta claves, no personas.
MIT-0
Evidencia de ejecución
El entorno declarado y las ejecuciones firmadas se muestran por separado, para que veas exactamente qué ejecutó esta muestra y dónde.
- Base de evidencia
- Contrato firmado aprobado
- Recibos de verificación
- 1
- Claves de firma que lo compilaron
- 1
Entorno declarado
dart 3 linux x64 dart 3 dart pub
Entornos de las ejecuciones de verificación
| Entorno | Contrato | Etapas | Ejecución |
|---|---|---|---|
| dart 3 · linux alpine/x64 · docker ed25519:a2ec939a4c60e243 | PASS | compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS CONTAINER_RUN · pub@1 |
2026-08-14 |
Caso
HOW- Objetivo
- Write fromJson and toJson by hand in Dart with dart:convert and json_annotation, with no build_runner and no generated file, and find out where an unchecked payload actually fails
- Paquetes
- Símbolos
-
- jsonDecode
- jsonEncode
- JsonUnsupportedObjectError
- JsonConverter
- JsonKey
- JsonSerializable
- $checkedCreate
- $checkedConvert
- $checkKeys
- CheckedFromJsonException
- MissingRequiredKeysException
- UnrecognizedKeysException
- DisallowedNullValueException
- DateTime.parse
- DateTime.toIso8601String
- Entorno
- dart 3
- Creado
- 2026-08-14T20:06:25Z
Contrato
- assert a payload whose every field has the wrong type still decodes, that reading a field out of it still succeeds because both are typed dynamic, and that the first failure is a TypeError at the first typed use in code that never mentions JSON, with reviver the only hook that runs during the decode itself
- assert a decoded array is List<dynamic> and is not a List<String> even when every element is a String, and that the usual .cast<String>() fix defers again into a lazy view whose construction and length succeed with a bad element inside while reading that element throws, where List<String>.from fails at the decode
- assert a JSON number is int or double according to how it was spelled, so as int rejects 3.0 and as double rejects 3, that num survives both at the cost of a silent truncation in toInt, and that an integer literal past the 64-bit range decodes as a double with its low digits already gone
- assert a missing key reads back as null without throwing and is indistinguishable from an explicit null except through containsKey, that it becomes a TypeError in a non-nullable field and silence in a nullable one, and that $checkKeys separates missing, unrecognized and disallowed-null into three named exceptions before any value is read
- assert decoding gives a String and encoding a DateTime throws, that DateTime.parse returns UTC for a numeric offset as well as for a trailing Z so the offset is lost on the way out rather than on the way in, that toIso8601String writes no zone designator at all for a non-UTC value, and that the round trip is not == the original because DateTime's == compares the isUtc flag
- assert jsonEncode resolves toJson by dynamic dispatch with no interface involved, that a class without one throws JsonUnsupportedObjectError caused by NoSuchMethodError, and that a toJson returning an unencodable value re-attributes the error to your class with the real offender only reachable through cause
- assert $checkedCreate and $checkedConvert turn the same TypeError into a CheckedFromJsonException naming the class and the JSON key, including the key rather than the Dart field name and including a key that was missing, while leaving a good payload untouched
- assert @JsonSerializable and @JsonKey change nothing at runtime without the generator, so the declared rename and default value are ignored and the hand-written code is what decides the wire key
Archivos
- csx.json
- lib/product.dart
- probe.dart
- pubspec.lock
- pubspec.yaml
- test/contract_test.dart