Ef Core-使用Automapper从无钥匙视图获取数据

Question

我需要知道是否可以使用Automapper从数据库视图映射DTO属性。或者在DbContext模型配置中也有可能。让我们想象一下，我有一个包含其他相关数据的视图的商业目的，但为了简洁起见，我将类简化为

相关的Nugets

• EF Core 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; }
}

我有一个无钥匙查看

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

该视图构建在DB Initializer类中

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类中的DbSet

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

在我的FooDto中，我需要实体类的一个附加属性，该属性将指示此Foo存在于我的数据库视图v_Bar 中

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

对于Automapper配置，我有以下内容，但据我所知，没有一种方法可以将我的dto属性从BarVW DbSet 映射到IsBar

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该属性(例如，opt.MapFrom(src => src.Bars.Any())(。

下面是一个完全工作的示例控制台程序，它演示了这种方法：

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]

您可以使用.NET Fiddle运行示例代码。