JSON to Dart Model Class Generator

From JSON to Flutter models

1. Paste a JSON response into the input box. Use Sample if you just want to see the output.
2. Enter a root class name. Nested objects become their own classes, named from their keys.
3. Switch toJson off if you only read data and never send it back.
4. Copy the Dart code into a file in your models folder.

What you get

Each class has final fields, a constructor with required named parameters, a factory fromJson(Map<String, dynamic> json) and, optionally, a toJson() method. Numbers are typed as int or double depending on the sample, and a double is read through (value as num).toDouble() so a JSON 1 does not crash a field that is usually 1.5.

Lists of objects are mapped with .map((e) => Item.fromJson(e as Map<String, dynamic>)).toList(). Lists of strings, numbers and booleans keep their element type.

Things to check

• Null in the sample produces a dynamic field, because the real type is unknown. Replace it once you know the type.
• Mixed types in one key, such as a string in one record and a number in another, also fall back to dynamic.
• Reserved words like class or default as keys get a Value suffix, for example classValue.
• Dates arrive as strings. Convert them with DateTime.parse in your own code if you need a DateTime.
• If you add json_serializable later, keep the class names and replace the hand-written methods with annotations.

Good habits

Feed the tool a response that contains every optional field, run your app against real data, and watch for cast errors in the console. A wrong type in fromJson fails loudly at runtime, which is how you find fields the sample did not cover.