Roslyn生成DTO及影子编程的尝试

xiangji2026-08-28 10:03

1. DTO含有大量重复代码

1.1 实体类Comment代码如下

csharp 复制代码 
/// <summary>
/// 评论
/// </summary>
/// <param name="id"></param>
/// <param name="createTime"></param>
public class Comment(CommentId id, CommentCreateTime createTime)
{
    /// <summary>
    /// 评论标识
    /// </summary>
    public CommentId Id { get; } = id;
    /// <summary>
    /// 评论内容
    /// </summary>
    public CommentContent Content { get; set; }
    /// <summary>
    /// 评论创建时间
    /// </summary>
    public CommentCreateTime CreateTime { get; } = createTime;
    /// <summary>
    /// 评论更新时间
    /// </summary>
    public CommentUpdateTime UpdateTime { get; set; }
}
/// <summary>
/// 评论标识
/// </summary>
/// <param name="Original"></param>
public readonly record struct CommentId(long Original) : IEntityId;
/// <summary>
/// 评论内容
/// </summary>
/// <param name="Original"></param>
public readonly record struct CommentContent(string Original) : IEntityProperty<string>;
/// <summary>
/// 评论创建时间
/// </summary>
/// <param name="Original"></param>
public readonly record struct CommentCreateTime(DateTime Original) : IEntityProperty<DateTime>;
/// <summary>
/// 评论更新时间
/// </summary>
/// <param name="Original"></param>
public readonly record struct CommentUpdateTime(DateTime Original) : IEntityProperty<DateTime>;

1.2 该CURD的DTO类型可能就会有很多重复代码

csharp 复制代码 
public sealed class CreateRequest
{
    public string Content { get; set; }
}
public sealed class CreateResponse : ResponseBase
{
    public long Id { get; set; }
}
public sealed class DeleteRequest
{
    public long Id { get; set; }
}
public sealed class DeleteResponse : ResponseBase
{
    public long Id { get; set; }
}
public sealed class UpdateRequest
{
    public long Id { get; set; }
}
public sealed class UpdateResponse : ResponseBase
{
    public long Id { get; set; }
}
public sealed class DetailRequest
{
    public long Id { get; set; }
}
public sealed class DetailResponse : ResponseBase
{
    public long Id { get; set; }
    public string Content { get; set; }
    public DateTime CreateTime { get; set; }
    public DateTime UpdateTime { get; set; }
}
public sealed class ListRequest
{
    public int Page { get; set; } = 1;
    public int Size { get; set; } = 10;
}
public sealed class ListResponse : ResponseBase
{
    public int Total { get; set; }
    public CommentItem[] Items { get; set; }
}
public class CommentItem
{
    public long Id { get; set; }
    public string Content { get; set; }
    public DateTime CreateTime { get; set; }
    public DateTime UpdateTime { get; set; }
}

1.3 使用代码生成器可以减少重复代码

  • 如下开源项目GeneratePoco生成器为5个DTO类生成属性,节省了大量重复代码
  • 如果属性太少生成器的收益不大
  • GeneratePoco的泛型参数标记了该类型与哪个实体类相关联,也就是说是哪个类型的附属类或者影子类
  • 通过ConvertFrom和ConvertTo配置是否生成从实体类到DTO的转换方法,或者从DTO到实体类的转换方法
csharp 复制代码 
[GeneratePoco<Comment>(ConvertFrom = true, ConvertTo = false)]
public partial class CreateResponse : ResponseBase;
[GeneratePoco<Comment>(Rules = [$"Include: {nameof(Comment.Id)}"], ConvertTo = false)]
public partial class DeleteResponse : ResponseBase;
[GeneratePoco<Comment>(Rules = [$"Include: {nameof(Comment.Id)}"], ConvertTo = false)]
public partial class UpdateResponse : ResponseBase;
[GeneratePoco<Comment>(ConvertFrom = true, ConvertTo = false)]
public partial class DetailResponse : ResponseBase;
[GeneratePoco<Comment>(ConvertFrom = true, ConvertTo = false)]
public partial class CommentItem;

1.4 生成代码如下

  • 由源实体的强类型属性生成基本类型的DTO属性,是GeneratePoco的应用场景之一
  • ConvertFrom的方法生成为源类型的静态扩展方法
  • ConvertTo的方法生成为目标类型的实例方法
  • 如果源类型属性有注释，生成的DTO属性也会包含相应的注释
  • 如果DTO属性名与源类型属性名不一致，可以通过Rules配置,参看SourceGenerator之扑风捉影
csharp 复制代码 
namespace GenerateApp.Create
{
    partial class CreateResponse
    {
        ///<summary>
        ///评论标识
        ///</summary>
        public long Id { get; set; }
        ///<summary>
        ///评论内容
        ///</summary>
        public string Content { get; set; }
        ///<summary>
        ///评论创建时间
        ///</summary>
        public DateTime CreateTime { get; set; }
        ///<summary>
        ///评论更新时间
        ///</summary>
        public DateTime UpdateTime { get; set; }
    }
}
namespace CommentModels
{
    using GenerateApp.Create;
    internal static partial class CommentExtensions
    {
        ///<summary>
        ///转化
        ///</summary>
        ///<param name = "message"></param>
        public static CreateResponse ToCreateResponse(this Comment @this) => new()
        {
            Id = @this.Id.Original,
            Content = @this.Content.Original,
            CreateTime = @this.CreateTime.Original,
            UpdateTime = @this.UpdateTime.Original
        };
    }
}
namespace GenerateApp.Delete
{
    partial class DeleteResponse
    {
        ///<summary>
        ///评论标识
        ///</summary>
        public long Id { get; set; }
    }
}
namespace GenerateApp.Update
{
    partial class UpdateResponse
    {
        ///<summary>
        ///评论标识
        ///</summary>
        public long Id { get; set; }
    }
}
namespace GenerateApp.Detail
{
    partial class DetailResponse
    {
        ///<summary>
        ///评论标识
        ///</summary>
        public long Id { get; set; }
        ///<summary>
        ///评论内容
        ///</summary>
        public string Content { get; set; }
        ///<summary>
        ///评论创建时间
        ///</summary>
        public DateTime CreateTime { get; set; }
        ///<summary>
        ///评论更新时间
        ///</summary>
        public DateTime UpdateTime { get; set; }
    }
}
namespace CommentModels
{
    using GenerateApp.Detail;
    internal static partial class CommentExtensions
    {
        ///<summary>
        ///转化
        ///</summary>
        ///<param name = "message"></param>
        public static DetailResponse ToDetailResponse(this Comment @this) => new()
        {
            Id = @this.Id.Original,
            Content = @this.Content.Original,
            CreateTime = @this.CreateTime.Original,
            UpdateTime = @this.UpdateTime.Original
        };
    }
}
namespace GenerateApp.List
{
    partial class CommentItem
    {
        ///<summary>
        ///评论标识
        ///</summary>
        public long Id { get; set; }
        ///<summary>
        ///评论内容
        ///</summary>
        public string Content { get; set; }
        ///<summary>
        ///评论创建时间
        ///</summary>
        public DateTime CreateTime { get; set; }
        ///<summary>
        ///评论更新时间
        ///</summary>
        public DateTime UpdateTime { get; set; }
    }
}
namespace CommentModels
{
    using GenerateApp.List;
    internal static partial class CommentExtensions
    {
        ///<summary>
        ///转化
        ///</summary>
        public static CommentItem ToItem(this Comment @this) => new()
        {
            Id = @this.Id.Original,
            Content = @this.Content.Original,
            CreateTime = @this.CreateTime.Original,
            UpdateTime = @this.UpdateTime.Original
        };
    }
}

1.5 应用业务逻辑

1.5.1 原始的业务逻辑代码

csharp 复制代码 
    private readonly ICommentService _service = service;

    public override Task<CreateResponse> ExecuteAsync(CreateRequest req, CancellationToken ct)
    {
        var content = new CommentContent(req.Content);
        var comment = _service.AddComment(content);
        var res = new CreateResponse()
        {
            Id = comment.Id.Original,
            Content = comment.Content.Original,
            CreateTime = comment.CreateTime.Original,
            UpdateTime = comment.UpdateTime.Original,
        };
        return Task.FromResult(res);
    }

1.5.2 使用代码生成的DTO的业务逻辑代码

  • GeneratePoco生成的类型转化方法代替了Mapper,简化了业务逻辑代码
  • 开源项目GeneratePoco的Mapper功能是通过引用开源项目GenerateConvert来实现的
  • GenerateConvert本身可以单独用来生成Mapper代码,有点类似开源项目mapperly
csharp 复制代码 
    private readonly ICommentService _service = service;

    public override Task<CreateResponse> ExecuteAsync(CreateRequest req, CancellationToken ct)
    {
        var content = new CommentContent(req.Content);
        var comment = _service.AddComment(content);
        return Task.FromResult(comment.ToCreateResponse());
    }

1.6 Roslyn生成DTO现存的问题

  • 生成器执行顺序问题
  • DTO可以通过JsonSourceGenerator生成序列化的代码来提高性能和AOT支持等
  • 但是JsonSourceGenerator的执行顺序在GeneratePoco之前,生成的序列化代码不包含GeneratePoco生成的属性
  • 所以使用GeneratePoco的类型不能使用JsonSourceGenerator生成器
  • 这个问题将来某个时间微软应该会解决
  • 暂时我也没有找到解决方案

1.7 以上示例代码已经上传到github,可以直接查看

2. 可以用GenerateConvert来做类型转化

2.1 转化为DTO的Case

  • Car转化为CarDto

2.1.1 Car及相关类

csharp 复制代码 
public class Car
{
    public string Name { get; set; } = string.Empty;
    public int NumberOfSeats { get; set; }
    public CarColor Color { get; set; }
    public Manufacturer? Manufacturer { get; set; }
    public List<Tire> Tires { get; set; } = [];
    public LicensePlate LicensePlate { get; set; }
}
public enum CarColor
{
    Black = 1,
    Blue = 2,
    White = 3,
}
public class Manufacturer(int id, string name)
{
    public int Id { get; } = id;
    public string Name { get; } = name;
}
public class Tire
{
    public string Description { get; set; } = string.Empty;
}
public readonly struct LicensePlate(string  value)
{
    public string Value { get;} = value;

    public override readonly string ToString() => Value;
}

2.1.1 CarDto及相关类

csharp 复制代码 
public class CarDto
{
    public string Name { get; set; } = string.Empty;
    public int NumberOfSeats { get; set; }
    public CarColorDto Color { get; set; }
    public ProducerDto? Producer { get; set; }
    public List<TireDto>? Tires { get; set; }
    public string LicensePlate { get; set; } = string.Empty;
}
public enum CarColorDto
{
    Yellow = 1,
    Green = 2,
    Black = 3,
    Blue = 4,
}
public class ProducerDto(int id, string name)
{
    public int Id { get; } = id;
    public string Name { get; } = name;
}
public class TireDto(string description)
{
    public string Description { get; set; } = description;
}

2.2 可以用GenerateConvert来做类型转化

2.2.1 GenerateConvert配置代码

  • 把CarDto设置为partial
  • 增加GenerateConvert<Car>标记
  • 配置ConvertFrom = true生成Car转化为
  • Rules配置同前面GeneratePoco的Rules,是通过投影规则定义成员映射规则
  • 这里定义了CarDto的Producer隐射到Car的Manufacturer
csharp 复制代码 
[GenerateConvert<Car>(
    Rules = [
        $"Map {nameof(Producer)}, {nameof(Car.Manufacturer)}"
    ],
    ConvertTo = false,
    ConvertFrom = true
)]
public partial class CarDto
{
    public string Name { get; set; } = string.Empty;
    public int NumberOfSeats { get; set; }
    public CarColorDto Color { get; set; }
    public ProducerDto? Producer { get; set; }
    public List<TireDto>? Tires { get; set; }
    public string LicensePlate { get; set; } = string.Empty;
}

2.2.2 GenerateConvert生成的代码

  • 生成了4个扩展方法
  • 其中Car.ToDto是入口方法
  • 这些方法都很简洁,几乎和手写的一样
  • 每个方法都有summary注释
csharp 复制代码 
using ConvertDemo.Models;

internal static partial class CarExtensions
{
    ///<summary>
    ///转化为CarDto
    ///</summary>
    public static CarDto ToDto(this Car @this) => new()
    {
        Name = @this.Name,
        NumberOfSeats = @this.NumberOfSeats,
        Color = @this.Color.ToDto(),
        Producer = @this.Manufacturer == null ? default : @this.Manufacturer.ToProducerDto(),
        Tires = @this.Tires.ConvertAll(item => item.ToDto()),
        LicensePlate = @this.LicensePlate.Value
    };
}
internal static partial class CarColorExtensions
{
    ///<summary>
    ///转化为CarColorDto
    ///</summary>
    public static CarColorDto ToDto(this CarColor @this) => @this switch
    {
        CarColor.Black => CarColorDto.Black,
        CarColor.Blue => CarColorDto.Blue,
        _ => default
    };
}
internal static partial class ManufacturerExtensions
{
    ///<summary>
    ///转化为ProducerDto
    ///</summary>
    public static ProducerDto? ToProducerDto(this Manufacturer @this) => new(@this.Id, @this.Name);
}
internal static partial class TireExtensions
{
    ///<summary>
    ///转化为TireDto
    ///</summary>
    public static TireDto ToDto(this Tire @this) => new(@this.Description);
}

2.3 也可以用mapperly实现这个需求

2.3.1 mapperly配置代码

  • 新建partial类CarMapper
  • 增加Mapper特性配置
  • 增加一个Car转化为CarDto的partial方法
  • 通过MapProperty配置映射规则
csharp 复制代码 
[Mapper(EnumMappingStrategy = EnumMappingStrategy.ByName)]
public static partial class CarMapper
{
    [MapProperty(nameof(Car.Manufacturer), nameof(CarDto.Producer))] 
    public static partial CarDto MapCarToDto(Car car);
}

2.3.2 mapperly生成代码

  • 生成了5个静态方法
  • 1个公开的入口,4个私有的静态方法,并不能单独使用
  • 类名都用global+全命名空间
csharp 复制代码 
public static partial class CarMapper
{
    [global::System.CodeDom.Compiler.GeneratedCode("Riok.Mapperly", "4.3.1.0")]
    public static partial global::MapperlyDemo.Models.CarDto MapCarToDto(global::Demo.Models.Car car)
    {
        var target = new global::MapperlyDemo.Models.CarDto();
        target.Name = car.Name;
        target.NumberOfSeats = car.NumberOfSeats;
        target.Color = MapToCarColorDto(car.Color);
        if (car.Manufacturer != null)
        {
            target.Producer = MapToProducerDto(car.Manufacturer);
        }
        else
        {
            target.Producer = null;
        }
        target.Tires = MapToListOfTireDto(car.Tires);
        target.LicensePlate = car.LicensePlate.ToString();
        return target;
    }

    [global::System.CodeDom.Compiler.GeneratedCode("Riok.Mapperly", "4.3.1.0")]
    private static global::MapperlyDemo.Models.CarColorDto MapToCarColorDto(global::Demo.Models.CarColor source)
    {
        return source switch
        {
            global::Demo.Models.CarColor.Black => global::MapperlyDemo.Models.CarColorDto.Black,
            global::Demo.Models.CarColor.Blue => global::MapperlyDemo.Models.CarColorDto.Blue,
            _ => throw new global::System.ArgumentOutOfRangeException(nameof(source), source, "The value of enum CarColor is not supported"),
        };
    }

    [global::System.CodeDom.Compiler.GeneratedCode("Riok.Mapperly", "4.3.1.0")]
    private static global::MapperlyDemo.Models.ProducerDto MapToProducerDto(global::Demo.Models.Manufacturer source)
    {
        var target = new global::MapperlyDemo.Models.ProducerDto(source.Id, source.Name);
        return target;
    }

    [global::System.CodeDom.Compiler.GeneratedCode("Riok.Mapperly", "4.3.1.0")]
    private static global::MapperlyDemo.Models.TireDto MapToTireDto(global::Demo.Models.Tire source)
    {
        var target = new global::MapperlyDemo.Models.TireDto();
        target.Description = source.Description;
        return target;
    }

    [global::System.CodeDom.Compiler.GeneratedCode("Riok.Mapperly", "4.3.1.0")]
    private static global::System.Collections.Generic.List<global::MapperlyDemo.Models.TireDto> MapToListOfTireDto(global::System.Collections.Generic.IReadOnlyCollection<global::Demo.Models.Tire> source)
    {
        var target = new global::System.Collections.Generic.List<global::MapperlyDemo.Models.TireDto>(source.Count);
        foreach (var item in source)
        {
            target.Add(MapToTireDto(item));
        }
        return target;
    }
}

2.4 用GenerateConvert实现互转

2.4.1 GenerateConvert互转配置代码

  • 与2.2示例唯一区别就是ConvertTo配置为true
csharp 复制代码 
[GenerateConvert<Car>(
    Rules = [
        $"Map {nameof(Producer)}, {nameof(Car.Manufacturer)}"
    ],
    ConvertTo = true,
    ConvertFrom = true
)]
public partial class CarDto
{
    public string Name { get; set; } = string.Empty;
    public int NumberOfSeats { get; set; }
    public CarColorDto Color { get; set; }
    public ProducerDto? Producer { get; set; }
    public List<TireDto>? Tires { get; set; }
    public string LicensePlate { get; set; } = string.Empty;
}

2.4.2 GenerateConvert互转生成的代码

  • 比2.2示例多生成以下4个方法
  • 其中2个实例方法2个扩展方法
  • 如果转化源类为当前程序集的partial类就会生成实例方法,否则生成扩展方法
csharp 复制代码 
namespace ConvertDemo.Models;
partial class CarDto
{
    ///<summary>
    ///转化为Car
    ///</summary>
    public Car ToCar() => new()
    {
        Name = Name,
        NumberOfSeats = NumberOfSeats,
        Color = Color.ToCarColor(),
        Manufacturer = Producer == null ? default : Producer.ToManufacturer(),
        Tires = Tires == null ? [] : Tires.ConvertAll(item => item.ToTire()),
        LicensePlate = new LicensePlate(LicensePlate)
    };
}
public static partial class CarColorDtoExtensions
{
    ///<summary>
    ///转化为CarColor
    ///</summary>
    public static CarColor ToCarColor(this CarColorDto @this) => @this switch
    {
        CarColorDto.Black => CarColor.Black,
        CarColorDto.Blue => CarColor.Blue,
        _ => default
    };
}
partial class ProducerDto
{
    ///<summary>
    ///转化为Manufacturer
    ///</summary>
    public Manufacturer? ToManufacturer() => new(Id, Name);
}
public static partial class TireDtoExtensions
{
    ///<summary>
    ///转化为Tire
    ///</summary>
    public static Tire ToTire(this TireDto @this) => new()
    {
        Description = @this.Description
    };
}

2.5 用mapperly实现互转

2.5.1 mapperly互转配置代码

  • 比2.3示例多1个方法MapDtoToCar及其MapProperty特性配置
csharp 复制代码 
[Mapper(EnumMappingStrategy = EnumMappingStrategy.ByName)]
public static partial class CarMapper
{
    [MapProperty(nameof(Car.Manufacturer), nameof(CarDto.Producer))]
    public static partial CarDto MapCarToDto(Car car);

    [MapProperty(nameof(CarDto.Producer), nameof(Car.Manufacturer))]
    public static partial Car MapDtoToCar(CarDto car);
}

2.5.2 mapperly互转生成代码

  • 比2.3示例多生成了5个静态方法
  • 其中1个公开的入口方法及4个私有的静态方法
  • 类名都用global+全命名空间
csharp 复制代码 
public static partial class CarMapper
{
    [global::System.CodeDom.Compiler.GeneratedCode("Riok.Mapperly", "4.3.1.0")]
    public static partial global::Demo.Models.Car MapDtoToCar(global::MapperlyDemo.Models.CarDto car)
    {
        var target = new global::Demo.Models.Car();
        target.Name = car.Name;
        target.NumberOfSeats = car.NumberOfSeats;
        target.Color = MapToCarColor(car.Color);
        if (car.Producer != null)
        {
            target.Manufacturer = MapToManufacturer(car.Producer);
        }
        else
        {
            target.Manufacturer = null;
        }
        if (car.Tires != null)
        {
            target.Tires = MapToListOfTire(car.Tires);
        }
        target.LicensePlate = new global::Demo.Models.LicensePlate(car.LicensePlate);
        return target;
    }
    
    [global::System.CodeDom.Compiler.GeneratedCode("Riok.Mapperly", "4.3.1.0")]
    private static global::Demo.Models.CarColor MapToCarColor(global::MapperlyDemo.Models.CarColorDto source)
    {
        return source switch
        {
            global::MapperlyDemo.Models.CarColorDto.Black => global::Demo.Models.CarColor.Black,
            global::MapperlyDemo.Models.CarColorDto.Blue => global::Demo.Models.CarColor.Blue,
            _ => throw new global::System.ArgumentOutOfRangeException(nameof(source), source, "The value of enum CarColorDto is not supported"),
        };
    }
    
    [global::System.CodeDom.Compiler.GeneratedCode("Riok.Mapperly", "4.3.1.0")]
    private static global::Demo.Models.Manufacturer MapToManufacturer(global::MapperlyDemo.Models.ProducerDto source)
    {
        var target = new global::Demo.Models.Manufacturer(source.Id, source.Name);
        return target;
    }
    
    [global::System.CodeDom.Compiler.GeneratedCode("Riok.Mapperly", "4.3.1.0")]
    private static global::Demo.Models.Tire MapToTire(global::MapperlyDemo.Models.TireDto source)
    {
        var target = new global::Demo.Models.Tire();
        target.Description = source.Description;
        return target;
    }
    
    [global::System.CodeDom.Compiler.GeneratedCode("Riok.Mapperly", "4.3.1.0")]
    private static global::System.Collections.Generic.List<global::Demo.Models.Tire> MapToListOfTire(global::System.Collections.Generic.IReadOnlyCollection<global::MapperlyDemo.Models.TireDto> source)
    {
        var target = new global::System.Collections.Generic.List<global::Demo.Models.Tire>(source.Count);
        foreach (var item in source)
        {
            target.Add(MapToTire(item));
        }
        return target;
    }
}

2.6 GenerateConvert和mapperly的对比

  • 以下是GenerateConvert和mapperly的对比,你喜欢哪种

2.6.1 命名空间处理

特性 GenerateConvert mapperly
同名类处理 有同名类型才增加命名空间 直接global+命名空间+类名，不用单独处理
引用 把命名空间提取为using 无using
简洁性 更好 大量重复代码
准确性 同名类且命名空间包含可能导致错误 同名类只要命名空间不完全相同就不会出错

2.6.2 映射配置

特性 GenerateConvert mapperly
完善性 支持同名、前缀、后缀、替换、一对一等及Filter、Through和Cross投影 同名、一对一、忽略等
复用性 互转可共用配置且与集成的GeneratePoco共用 每个转化方法单独配置

2.6.3 调用方法

特性 GenerateConvert mapperly
入口方法 实例方法或扩展方法,按实例调用 调用Mapper的方法
辅助方法 也是方法或扩展方法,按实例调用 私有,不可单独调用

2.7 GenerateConvert项目信息

3. 更多生成器的应用

3.1 GeneratePoco生成构造函数

3.1.1 生成构造函数默认样式

3.1.1.1 配置代码
  • Initializer配置为InitializeKind.Constructor
csharp 复制代码 
public record User(int Id, string Name);
[GeneratePoco<User>(Initializer = InitializeKind.Constructor)]
public partial class UserDto;
3.1.1.2 生成代码
csharp 复制代码 
partial class UserDto(int id, string name)
{
    public int Id { get; } = id;
    public string Name { get; } = name;
    public User ToUser() => new(Id, Name);
}

3.1.2 生成构造函数含字段样式

3.1.2.1 配置代码
  • Initializer配置为InitializeKind.Constructor | InitializeKind.Field
csharp 复制代码 
public record User(int Id, string Name);
[GeneratePoco<User>(Initializer = InitializeKind.Constructor | InitializeKind.Field)]
public partial class UserDto;
3.1.2.2 生成代码
csharp 复制代码 
partial class UserDto(int id, string name)
{
    private readonly int _id = id;
    private readonly string _name = name;
    public int Id => _id;
    public string Name => _name;
    public User ToUser() => new(_id, _name);
}

3.1.3 生成构造函数设置属性样式

3.1.3.1 配置代码
  • Initializer配置为InitializeKind.Constructor | InitializeKind.Property
csharp 复制代码 
public record User(int Id, string Name);
[GeneratePoco<User>(Initializer = InitializeKind.Constructor | InitializeKind.Property)]
public partial class UserDto;
3.1.3.2 生成代码
csharp 复制代码 
partial class UserDto(int id, string name)
{
    public int Id { get; set; } = id;
    public string Name { get; set; } = name;
    public User ToUser() => new(Id, Name);
}

3.1.4 生成构造函数设置字段及属性样式

3.1.4.1 配置代码
  • Initializer配置为InitializeKind.Constructor | InitializeKind.Property | InitializeKind.Field
csharp 复制代码 
public record User(int Id, string Name);
[GeneratePoco<User>(Initializer = InitializeKind.Constructor | InitializeKind.Property | InitializeKind.Field)]
public partial class UserDto;
3.1.4.2 生成代码
csharp 复制代码 
partial class UserDto(int id, string name)
{
    private int _id = id;
    private string _name = name;
    public int Id { get => _id; set => _id = value; }
    public string Name { get => _name; set => _name = value; }
    public GeneratePocoTests.User ToUser() => new(_id, _name);
}

3.1.5 生成属性默认样式

3.1.5.1 配置代码
  • Initializer配置为InitializeKind.Constructor
csharp 复制代码 
public record User(int Id, string Name);
[GeneratePoco<User>(Initializer = InitializeKind.Property)]
public partial class UserDto;
3.1.5.2 生成代码
csharp 复制代码 
partial class UserDto
{
    public int Id { get; set; }
    public string Name { get; set; }
    public User ToUser() => new(Id, Name);
}

3.1.6 生成属性Init样式

3.1.6.1 配置代码
  • Initializer配置为InitializeKind.Init
csharp 复制代码 
public record User(int Id, string Name);
[GeneratePoco<User>(Initializer = InitializeKind.Init)]
public partial class UserDto;
3.1.6.2 生成代码
csharp 复制代码 
partial class UserDto
{
    public int Id { get; init; }
    public string Name { get; init; }
    public User ToUser() => new(Id, Name);
}

3.1.7 生成属性含字段样式

3.1.7.1 配置代码
  • Initializer配置为InitializeKind.Property | InitializeKind.Field
csharp 复制代码 
public record User(int Id, string Name);
[GeneratePoco<User>(Initializer = InitializeKind.Property | InitializeKind.Field)]
public partial class UserDto;
3.1.7.2 生成代码
csharp 复制代码 
partial class UserDto
{
    private int _id;
    private string _name;
    public int Id { get => _id; set => _id = value; }
    public string Name { get => _name; set => _name = value; }
    public GeneratePocoTests.User ToUser() => new(_id, _name);
}

3.1.8 生成属性Init含字段样式

3.1.8.1 配置代码
  • Initializer配置为InitializeKind.Init | InitializeKind.Field
csharp 复制代码 
public record User(int Id, string Name);
[GeneratePoco<User>(Initializer = InitializeKind.Init | InitializeKind.Field)]
public partial class UserDto;
3.1.8.2 生成代码
csharp 复制代码 
partial class UserDto
{
    private int _id;
    private string _name;
    public int Id { get => _id; init => _id = value; }
    public string Name { get => _name; init => _name = value; }
    public User ToUser() => new(_id, _name);
}

3.1.9 生成字段样式

3.1.9.1 配置代码
  • Initializer配置为InitializeKind.Field
csharp 复制代码 
public record User(int Id, string Name);
[GeneratePoco<User>(Initializer = InitializeKind.Field)]
public partial class UserDto;
3.1.9.2 生成代码
csharp 复制代码 
partial class UserDto
{
    public int Id;
    public string Name;
    public User ToUser() => new(Id, Name);
}

3.1.10 生成记录样式

3.1.10.1 配置代码
  • 需要目标类型为record(或struct record),Initializer不配置
csharp 复制代码 
public record User(int Id, string Name);
[GeneratePoco<User>()]
public partial record UserDto;
3.1.10.2 生成代码
csharp 复制代码 
partial record UserDto(int Id, string Name)
{
    public User ToUser() => new(Id, Name);
}

3.1.11 GeneratePoco其他配置属性

3.1.11.1 ConvertFrom/ConvertTo配置

  • ConvertFrom默认false,为true时生成从源类型到目标类型的静态扩展转换方法
  • ConvertTo默认true,为true时生成从目标类型到源类型的实例转换方法
  • 前面已有生成两种方法的示例,这里不再赘述

3.1.11.2 Rules配置

3.1.11.3 NullableRule配置

3.1.11.4 GenerateAttribute配置

  • GenerateAttribute默认false,为true时源类型属性的特性会被复制到目标类型属性(及其相关的字段和参数)上
  • 会判断源Attribute类型的AttributeUsage,是否适合应用到目标类型属性(及其相关的字段和参数)上,如果不适合则不会复制
csharp 复制代码 
// 配置代码
public class Product(int productId, string productName)
{
    public int ProductId { get; } = productId;
    [StringLength(100, MinimumLength = 6)]
    public string ProductName { get; } = productName;
}
[GeneratePoco<Product>(GenerateAttribute = true)]
public partial class ProductDto;
csharp 复制代码 
using GeneratePocoTests.Supports;
// 生成代码
partial class ProductDto
{
    public int ProductId { get; set; }

    [StringLength(100, MinimumLength = 6)]
    public string ProductName { get; set; }
    public Product ToProduct() => new(ProductId, ProductName);
}

3.1.11.5 Default配置

  • Default默认false,为true时生成默认默认值
  • 同一个属性及其相关的字段和参数之一生成默认值
  • 生成默认值的优先级是参数>字段>属性
csharp 复制代码 
// 配置代码
public record User(int Id, string Name);
[GeneratePoco<User>(Initializer = InitializeKind.Property | InitializeKind.Field, Default = true)]
public partial class UserDto;
csharp 复制代码 
// 生成代码
partial class UserDto
{
    private int _id = default;
    private string _name = "";
    public int Id { get => _id; set => _id = value; }
    public string Name { get => _name; set => _name = value; }
    public User ToUser() => new(_id, _name);
}

3.1.12 GeneratePoco不只是生成DTO

  • GeneratePoco实际上是生成十种不同的POCO类
  • 这十种样式并不全适合DTO
  • 也可以称之为影子类

3.2 GenerateTable生成器

  • GenerateTable生成器按实体类型生成表结构类
  • 生成的表结构类可以用于生成数据库表,也可以用于对数据表进行增删改查等操作
  • 一年前网友秦时明留言建议做源生成器,现在才补上会不会有点亡羊补牢的感觉
  • 可以参看ShadowSql.net之正确使用方式

3.2.1 GenerateTable配置代码

  • 通过Attribute配置表结构
  • Table配置表名
  • DatabaseGeneratedOption.Identity配置自增列
  • Key配置主键
  • Column配置了列名或数据库原始类型
  • Unique配置唯一索引(支持多列组合唯一)
csharp 复制代码 
[Table("Products")]
public class Product(int id, string name)
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int Id { get; } = id;
    [Unique]
    [Column("ProductName")]
    public string Name { get; } = name;
    [Unique("CategoryModel")]
    public int CategoryId { get; set; }
    [Unique("CategoryModel")]
    public string Model { get; set; }
}
[GenerateTable<Product>]
public partial class ProductTable;

3.2.2 GenerateTable生成代码

csharp 复制代码 
using ShadowSql.Identifiers;
partial class ProductTable : Table
{
    public ProductTable(string tableName = "Products") : base(tableName)
    {
        Id = DefineColumn("Id");
        Name = DefineColumn("Name", "ProductName");
        CategoryId = DefineColumn("CategoryId");
        Model = DefineColumn("Model");
        AddInsertIgnore(Id);
        AddUpdateIgnore(Id);
    }

    public IColumn Id { get; }
    public new IColumn Name { get; }
    public IColumn CategoryId { get; }
    public IColumn Model { get; }
}

3.2.2 GenerateTable项目信息

4. 部分其他源生成器开源项目

4.1 AutoDto

4.2 mapperly

4.3 MVVM Toolkit

5. 影子编程

  • 源生成器可以生成一个类的辅助类型(DTO、序列化、表结构等)
  • 这些辅助类型就相当于源类型的影子
  • 把周边功能影子化不仅减少了代码量,还提高了代码的可预测性和内聚性,也提高了代码的可读性。

6. 源生成器开发技巧总结

6.1 Roslyn简易语法

6.2 .net源生成器必须知道的4套类型

6.3 C#.NET源生成器如何处理Attribute

6.4 C#.NET源生成器如何处理XML注释文档

6.5 Roslyn语法的模式匹配之EasySyntax增加模式匹配支持

6.6 源生成器partial范式及单元测试

6.7 源生成器nuget打包

7. 示例说明

7.1 示例执行说明

以上代码执行依赖开源项目Hand.GeneratePoco和Hand.GenerateConvert及ShadowSql.GenerateTable,nuget包如下

Hand.GeneratePoco --version 0.2.1.19-alpha

Hand.GenerateConvert --version 0.2.1.17-alpha

ShadowSql.GenerateTable --version 0.9.1.1-alpha

7.2 示例代码及开源源码

7.2.1 GeneratePoco示例

7.2.2 GenerateConvert示例

7.2.3 Hand.GeneratePoco和Hand.GenerateConvert项目源码

7.2.4 ShadowSql.GenerateTable项目源码

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