# JSON Serialization (Flutter)

> json_serializable, fromJson/toJson, code generation, nested JSON, custom converters

- 20 interview questions
- Mid-Level
- [Interview Questions: Flutter](https://sharpskill.dev/en/technologies/flutter/interview-questions.md)

## 1. Which Flutter package is commonly used for automatic JSON serialization code generation?

**Answer**

The json_serializable package automatically generates fromJson and toJson serialization code from annotations. It works with build_runner to analyze annotations and generate the corresponding .g.dart file, reducing boilerplate code and manual errors.

## 2. Which annotation must be placed on a class to enable json_serializable code generation?

**Answer**

The @JsonSerializable() annotation tells build_runner that this class should have serialization code automatically generated. It is placed just before the class declaration and can accept optional parameters to customize serialization behavior.

## 3. Which command to run to generate serialization code with build_runner?

**Answer**

The command flutter pub run build_runner build triggers code generation for all annotated files. The --delete-conflicting-outputs option removes existing generated files before creating new ones, avoiding version conflicts.

## 17 more questions available

- Which file is generated by json_serializable for a User class defined in user.dart?
- Which Dart directive links the generated .g.dart file to the source class?

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