Create model classes with `fromJson` and `toJson` methods using `dart:convert`. Use when manually mapping JSON keys to class properties for simple data structures.

Serializing JSON Manually in Flutter Contents [Core Guidelines]( core guidelines) [Workflow: Implementing a Serializable Model]( workflow implementing a serializable model) [Workflow: Fetching and Parsing JSON]( workflow fetching and parsing json) [Examples]( examples) Core Guidelines Import dart:convert : Utilize Flutter's built in dart:convert library for manual JSON encoding ( jsonEncode ) and decoding ( jsonDecode ). Enforce Type Safety : Always cast the dynamic result of jsonDecode() to the expected type, typically Map<String, dynamic for objects or List<dynamic for arrays. Encapsulate Serialization Logic : Define plain model classes containing properties corresponding to the JSON structure. Implement a fromJson factory constructor and a toJson method within the model. Handle Background Parsing : If parsing large JSON documents (execution time 16ms), offload the parsing logic to a separate isolate using Flutter's compute() function to prevent UI jank. Throw Exceptions on Failure : When handling HTTP responses, throw an exception if the status code is not successful (e.g., not 200 OK or 201 Created). Do not return null . Workflow: Implementing a Serializable Model Use this checklist to implement manual JSON serialization for a data model. Task Progress: [ ] Define the plain model class with final properties. [ ] Implement the factory Model.fromJson(Map<String, dynamic json) constructor. [ ] Implement the Map<String, dynamic toJson() method. [ ] Write unit tests for both serialization methods. [ ] Run validator review type mismatch errors fix casting logic. 1. Define the Model : Create a class with properties matching the JSON keys. 2. Implement fromJson : Extract values from the Map and cast them to the appropriate Dart types. Use pattern matching or explicit casting. 3. Implement toJson : Return a Map<String, dynamic mapping the class properties back to their JSON string keys. 4. Validate : Execute unit tests to ensure type safety, autocompletion, and compile time exception handling function correctly. Workflow: Fetching and Parsing JSON Use this conditional workflow when retrieving and parsing JSON from a network request. Task Progress: [ ] Execute the HTTP request. [ ] Validate the response status code. [ ] Determine parsing strategy (Synchronous vs. Isolate). [ ] Decode and map the JSON to the model. 1. Execute Request : Use the http package to perform the network call. 2. Validate Response : If response.statusCode == 200 (or 201 for POST), proceed to parsing. If the status code indicates failure, throw an Exception . 3. Determine Parsing Strategy : If parsing a small payload (e.g., a single object), parse synchronously on the main thread. If parsing a large payload (e.g., an array of thousands of objects), use compute(parseFunction, response.body) to parse in a background isolate. 4. Decode and Map : Pass the decoded JSON to your model's fromJson constructor. Examples High Fidelity Model Implementation Synchronous Parsing (Small Payload) Background Parsing (Large Payload)

flutter-implement-json-serialization