Ef Core - 使用Automapper从keyless View获取数据

Question

我需要知道是否可以使用 Automapper 从数据库视图映射 DTO 属性。或者可能在 DbContext 模型配置中。假设我有一个包含其他相关数据的视图的业务目的，但为了简洁起见，我将 classes 简化为

相关的 Nugets

EF 核心 v3.1.7
AutoMapper v10.0.0

我有一个实体

public class Foo {
    public int Id { get; set; }
    public string Name { get; set; }
}

我有一个无钥匙视图

public class BarVW {
    public int FooId { get; set; }
    public string FooName { get; set; }
}

视图是在 DB Initializer 中构建的 class

context.Database.ExecuteSqlRaw(
    @"CREATE OR REPLACE VIEW v_Bar AS 
        select
            f.Id as FooId,
            f.[Name] as FooName
        from
            Foo f
        -- where some logic that makes a Foo appear in view"
);

然后将视图分配给DbContext中的一个DbSetclass

modelBuilder.Entity<BarVW>(eb =>
    {
        eb.HasNoKey();
        eb.ToView("v_Bar");
    });

public DbSet<BarVW> BarVW { get; set; }

在我的 FooDto 中，我的实体 class 需要一个额外的属性，它将表明这个 Foo 存在于我的数据库视图中 v_Bar

public class FooDto {
    public int Id { get; set; }
    public string Name { get; set; }
    public bool IsBar { get; set; }
}

对于 Automapper 配置，我有以下配置，但我不知道有一种方法可以将我的 dto IsBar 属性从 BarVW DbSet

CreateMap<Foo, FooDto>()
   .ForMember(dto => dto.IsBar, opt => ??? ); // don't know what to put here

Answer 1

实现所需功能的一种简单方法是引入导航属性（例如 Bars）并在映射配置中使用它（例如 opt.MapFrom(src => src.Bars.Any())）。

这是一个完整的示例控制台程序，演示了这种方法：

using System.Diagnostics;
using System.Linq;
using AutoMapper;
using AutoMapper.QueryableExtensions;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Logging;

namespace IssueConsoleTemplate
{
    public class Foo
    {
        public int Id { get; set; }
        public string Name { get; set; }
        
        public BarVW Bar { get; set; }
    }

    public class BarVW
    {
        public int FooId { get; set; }
        public string FooName { get; set; }
        
        public Foo Foo { get; set; }
    }
    
    public class Context : DbContext
    {
        public virtual DbSet<Foo> Foo { get; set; }
        public virtual DbSet<BarVW> BarVW { get; set; }

        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        {
            optionsBuilder
                .UseSqlServer(
                    @"Data Source=.\MSSQL14;Integrated Security=SSPI;Initial Catalog=So63850736")
                .UseLoggerFactory(LoggerFactory.Create(b => b
                    .AddConsole()
                    .AddFilter(level => level >= LogLevel.Information)))
                .EnableSensitiveDataLogging()
                .EnableDetailedErrors();
        }

        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            modelBuilder.Entity<Foo>()
                .HasData(
                    new Foo {Id = 1, Name = "Fo"},
                    new Foo {Id = 2, Name = "Foo"},
                    new Foo {Id = 3, Name = "Fooo"});

            modelBuilder.Entity<BarVW>(
                eb =>
                {
                    eb.HasKey(e => e.FooId);
                    eb.ToView("v_Bar");
                    eb.HasOne(e => e.Foo)
                        .WithOne(e => e.Bar)
                        .HasForeignKey<BarVW>(e => e.FooId);
                });
        }
    }
    
    public class FooDto
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public bool IsBar { get; set; }
    }

    internal static class Program
    {
        private static void Main()
        {
            using var context = new Context();

            context.Database.EnsureDeleted();
            context.Database.EnsureCreated();
            
            context.Database.ExecuteSqlRaw(
                @"CREATE VIEW [v_Bar] AS 
    select
        f.[Id] as [FooId],
        f.[Name] as [FooName]
    from
        [Foo] f
    where
        f.[Id] >= 1 and f.[Id] <= 2"
            );
            
            var config = new MapperConfiguration(
                cfg => cfg
                    .CreateMap<Foo, FooDto>()
                        .ForMember(dto => dto.IsBar, opt => opt.MapFrom(src => src.Bar != null)));
            
            var result = context.Foo
                .ProjectTo<FooDto>(config)
                .ToList();
            
            Debug.Assert(result.Count == 3);
            Debug.Assert(result.Count(dto => dto.IsBar) == 2);
        }
    }
}

为查询生成的 SQL 如下所示：

SELECT [f].[Id], CASE
    WHEN [v].[FooId] IS NOT NULL THEN CAST(1 AS bit)
    ELSE CAST(0 AS bit)
END AS [IsBar], [f].[Name]
FROM [Foo] AS [f]
LEFT JOIN [v_Bar] AS [v] ON [f].[Id] = [v].[FooId]

您可以运行使用 .NET Fiddle 的示例代码。

Ef Core - 使用Automapper从keyless View获取数据

Ef Core - Use Automapper to get data from keyless View

c#

sql-server

automapper

entity-framework-core