Flutter数据收集插件datacollection的使用

datacollection是一个用于从API响应生成数据集合的工具，它可以帮助你轻松地将API返回的数据转换为可操作的对象。以下是如何在Flutter项目中使用 datacollection 的详细步骤。

datacollection使用方法

1. 在 pubspec.yaml 中添加依赖项

首先，在项目的 pubspec.yaml 文件中添加必要的依赖项：

dependencies:
  datacollection: any
  json_annotation: any
  logger: any # 日志记录
  dio: any # HTTP 客户端
  retrofit: any # Retrofit 用于生成DIO路由

dev_dependencies:
  datacollection_generator: any
  http_mock_adapter: any
  retrofit_generator: any
  build_runner: '>2.3.0 <4.0.0'
  json_serializable: '>4.4.0'

然后运行以下命令以安装依赖项：

flutter pub get

Dart 注解

datacollection 提供了多种注解来帮助生成数据模型类。以下是常用的注解：

• @datacollections: 表示该类支持分页、集合和响应处理。
• @paginations: 支持分页功能。
• @collections: 支持集合操作。
• @response: 表示该类可以处理API响应。

示例代码

创建学生模型 (student.dart)

import 'package:datacollection/datacollection.dart';
import 'package:json_annotation/json_annotation.dart';

part 'student.g.dart'; // 自动生成的文件

[@JsonSerializable](/user/JsonSerializable)()
@paginations
@collections
@response
class Student {
  final String? name;
  final num? grade;
  final num? score;

  Student({
    this.name,
    this.grade,
    this.score,
  });

  factory Student.fromJson(Map<String, dynamic> json) => _$StudentFromJson(json);

  Map<String, dynamic> toJson() => _$StudentToJson(this);

  factory Student.fromMap(Map<String, dynamic> map) => _$StudentFromJson(map);

  Map<String, dynamic> toMap() => _$StudentToJson(this);
}

创建文章模型 (post.dart)

import 'package:collection/collection.dart';
import 'package:dio/dio.dart';
import 'package:json_annotation/json_annotation.dart';
import 'package:datacollection/datacollection.dart';
import 'package:retrofit/retrofit.dart';

part 'post.g.dart'; // 自动生成的文件

@RestApi(baseUrl: 'https://mylekha.app/api/v1/app/')
abstract class ClientPost {
  factory ClientPost(Dio dio, {String baseUrl}) = _ClientPost;

  @GET("/posts")
  Future<PaginationResponse<Post>> getPosts();

  @GET("/posts/{id}")
  Future<HttpResponse<Post>> getPost(@Path("id") int id);
}

[@JsonSerializable](/user/JsonSerializable)()
@datacollections
class Post {
  @JsonKey(defaultValue: null)
  final int? id;

  @JsonKey(defaultValue: "")
  final String? slug;

  @JsonKey(defaultValue: "")
  final String? title;

  @JsonKey(defaultValue: "")
  final String? content; // 文章内容

  @JsonKey(defaultValue: "post")
  final String? type; // 文章类型

  @JsonKey(defaultValue: null)
  final String? link; // 视频或音频链接

  @JsonKey(defaultValue: <String>[])
  final List<String>? images;

  @JsonKey(defaultValue: "en_US")
  final String? locale;

  Post({
    this.id,
    this.slug,
    this.title,
    this.content,
    this.type,
    this.link,
    this.images,
    this.locale,
  });

  factory Post.fromJson(Map<String, dynamic> json) => _$PostFromJson(json);

  Map<String, dynamic> toJson() => _$PostToJson(this);

  factory Post.fromMap(Map<String, dynamic> map) => _$PostFromJson(map);

  Map<String, dynamic> toMap() => _$PostToJson(this);

  Post copyWith({
    int? id,
    String? slug,
    String? title,
    String? content,
    String? type,
    String? link,
    List<String>? images,
    String? locale,
  }) {
    return Post(
      id: id ?? this.id,
      slug: slug ?? this.slug,
      title: title ?? this.title,
      content: content ?? this.content,
      type: type ?? this.type,
      link: link ?? this.link,
      images: images ?? this.images,
      locale: locale ?? this.locale,
    );
  }

  @override
  String toString() {
    return 'Post(id: $id, slug: $slug, title: $title, content: $content, type: $type, link: $link, images: $images, locale: $locale)';
  }

  @override
  bool operator ==(Object other) {
    if (identical(this, other)) return true;
    final listEquals = const DeepCollectionEquality().equals;

    return other is Post &&
        other.id == id &&
        other.slug == slug &&
        other.title == title &&
        other.content == content &&
        other.type == type &&
        other.link == link &&
        listEquals(other.images, images) &&
        other.locale == locale;
  }

  @override
  int get hashCode {
    return id.hashCode ^
        slug.hashCode ^
        title.hashCode ^
        content.hashCode ^
        type.hashCode ^
        link.hashCode ^
        images.hashCode ^
        locale.hashCode;
  }
}

运行代码生成器

在完成模型类的定义后，运行代码生成器以生成所需的 .g.dart 文件：

# 使用dart命令
pub run build_runner build

# 使用flutter命令
flutter pub run build_runner build

使用示例

以下是如何使用 PaginationResponse 和 Student 模型的示例：

void main() {
  // 模拟API返回的数据
  var data = [
    ...List.generate(10, (i) => {"name": "mr.$i", "age": i, "pass": i.isEven}).toList()
  ];

  // 创建分页响应对象
  var collection = PaginationResponse(data: data);
  expect(List<Map<String, dynamic>>, (collection.value.runtimeType),
      reason: "without T type, collection.value should be list of Map<String, dynamic>");

  // 创建带泛型的分页响应对象
  var studentCollection = PaginationResponse<Student>(data: data);
}

注解示例

以下是使用注解的两种方式：

方法一：直接使用注解

[@JsonSerializable](/user/JsonSerializable)()
@datacollections
class User {}

方法二：使用自定义注解

[@JsonSerializable](/user/JsonSerializable)()
[@DataCollectionAnnotation](/user/DataCollectionAnnotation)(
  paginations: true,
  collections: true,
  response: true,
)
class User {}