Flutter JSON转Floor实体类插件json_to_floor_entity的使用

内容

Contents

• Features
• Installation
• What does this library do
  • Get started
  • Examples
• Usage

Features

Installation

在pubspec.yaml文件中添加依赖：

dev_dependencies:
  json_to_floor_entity: last_version

然后运行以下命令安装：

pub get

如果你使用的是VSCode或Android Studio，也可以通过工具直接安装。

What does this library do

这是一个命令行工具，用于将.json文件转换为不可变的.dart模型。

Get started

该命令会遍历你的.json文件，查找可能的类型、变量名、导入路径、装饰器和类名，并将其写入模板中。

1. 在项目根目录下创建一个名为jsons的目录（默认）。
2. 将所有的.json文件复制到./jsons/目录中。
3. 运行以下命令：

   flutter pub run json_to_floor_entity
   

   或者指定源目录和输出目录：

   flutter pub run json_to_floor_entity -s assets/api_jsons -o lib/models
   

Examples

Input

假设我们有两个JSON文件：product.json和employee.json。

product.json

{
  "id": "123",
  "caseId?": "123",
  "startDate?": "2020-08-08",
  "endDate?": "2020-10-10",
  "placementDescription?": "Description string"
}

employee.json

{
  "id": "123",
  "displayName?": "Jan Jansen",
  "@ignore products?": "$[]product"
}

Output

这将生成以下两个Dart文件：product.dart和employee.dart。

product.dart

import 'package:floor/floor.dart';

@Entity(tableName: 'product')
class Product {

  const Product({
    required this.id,
    this.caseId,
    this.startDate,
    this.endDate,
    this.placementDescription,
  });

  @PrimaryKey(autoGenerate: true)
  final int id;
  final String? caseId;
  final String? startDate;
  final String? endDate;
  final String? placementDescription;

  factory Product.fromJson(Map<String, dynamic> json) => Product(
    id: json['id'] as String,
    caseId: json['caseId'] != null ? json['caseId'] as String : null,
    startDate: json['startDate'] != null ? json['startDate'] as String : null,
    endDate: json['endDate'] != null ? json['endDate'] as String : null,
    placementDescription: json['placementDescription'] != null ? json['placementDescription'] as String : null
  );

  Map<String, dynamic> toJson() => {
    'id': id,
    'caseId': caseId,
    'startDate': startDate,
    'endDate': endDate,
    'placementDescription': placementDescription
  };

  Product clone() => Product(
    id: id,
    caseId: caseId,
    startDate: startDate,
    endDate: endDate,
    placementDescription: placementDescription
  );

  Product copyWith({
    int? id,
    String? caseId,
    String? startDate,
    String? endDate,
    String? placementDescription
  }) => Product(
    id: id ?? this.id,
    caseId: caseId ?? this.caseId,
    startDate: startDate ?? this.startDate,
    endDate: endDate ?? this.endDate,
    placementDescription: placementDescription ?? this.placementDescription,
  );

  @override
  bool operator ==(Object other) => identical(this, other)
    || other is Product && id == other.id && caseId == other.caseId && startDate == other.startDate && endDate == other.endDate && placementDescription == other.placementDescription;

  @override
  int get hashCode => id.hashCode ^ caseId.hashCode ^ startDate.hashCode ^ endDate.hashCode ^ placementDescription.hashCode;
}

employee.dart

import 'package:floor/floor.dart';
import 'product.dart';

@Entity(tableName: 'employee')
class Employee {

  const Employee({
    required this.id,
    this.displayName,
    this.products,
  });

  @PrimaryKey(autoGenerate: true)
  final int id;
  final String? displayName;
  final List<Product>? products;

  factory Employee.fromJson(Map<String, dynamic> json) => Employee(
    id: json['id'] as String,
    displayName: json['displayName'] != null ? json['displayName'] as String : null
  );

  Map<String, dynamic> toJson() => {
    'id': id,
    'displayName': displayName
  };

  Employee clone() => Employee(
    id: id,
    displayName: displayName,
    products: products?.map((e) => e.clone()).toList()
  );

  Employee copyWith({
    int? id,
    String? displayName,
    List<Product>? products
  }) => Employee(
    id: id ?? this.id,
    displayName: displayName ?? this.displayName,
    products: products ?? this.products,
  );

  @override
  bool operator ==(Object other) => identical(this, other)
    || other is Employee && id == other.id && displayName == other.displayName && products == other.products;

  @override
  int get hashCode => id.hashCode ^ displayName.hashCode ^ products.hashCode;
}

Create a DAO (Data Access Object)

DAO负责管理对底层SQLite数据库的访问。可以通过以下方式自动生成DAO：

import 'package:floor/floor.dart';

@dao
abstract class NewsDao {

  @Query('SELECT * FROM News')
  Future<List<News>> findAll();

  @Query('SELECT * FROM News WHERE id = :id')
  Future<News?> findById(int id);

  @insert
  Future<void> add(News entity);
  
  @insert
  Future<void> addList(List<News> entities);

  @update
  Future<void> edit(News entity);

  @update
  Future<void> editList(List<News> entities);

  @delete
  Future<void> remove(News entity);

  @delete
  Future<void> removeList(List<News> entities);

}

这些文件在创建后不会被删除或更新。

Create the Database

数据库必须是一个扩展了FloorDatabase的抽象类。可以自动生成DAO：

// database.dart
// 必需的包导入
import 'dart:async';
import 'package:floor/floor.dart';
import 'package:sqflite/sqflite.dart' as sqflite;

import 'dao/person_dao.dart';
import 'entity/person.dart';

part 'database.g.dart'; // 生成的代码将在此处

@Database(version: 1, entities: [Person])
abstract class AppDatabase extends FloorDatabase {
  PersonDao get personDao;
}

Getting started

1. 在项目根目录下创建一个名为jsons的目录（默认）。
2. 将所有JSON文件放入jsons目录中。
3. 运行以下命令：

   pub run json_to_floor_entity
   

   或者指定源目录和输出目录：

   flutter pub run json_to_floor_entity -s assets/api_jsons -o lib/models
   

4. 运行以下命令生成代码：

   flutter packages pub run build_runner build