在 Entity Framework Core 7 或更低版本中使用原始 SQL 查询查询未映射的类型

Question

使用原始 SQL 查询查询未映射类型是否仅在 Entity Framework Core 8 中可用？我记得使用 Entity Framework 6 开发 ASP.NET Web API 项目，在该项目中我能够查询未映射的类型，而无需任何额外的配置。

当我尝试执行下面的查询时，出现异常

您的数据库提供商本身不支持“SqlQuery”方法中使用的元素类型“server.Data.BikeStore.Order”。使用受支持的元素类型，或使用 ModelConfigurationBuilder.DefaultTypeMapping 为您的类型定义映射。

List<Order> order = await _BSDB.Database
                               .SqlQuery<Order>(FormattableStringFactory.Create("select * from BikeStore.sales.orders"))
                               .ToListAsync();

我对

Order

实体的配置如下：

public partial class BikeStoreContext : DbContext 
{
    public BikeStoreContext() {}

    public BikeStoreContext(DbContextOptions<BikeStoreContext> options) : base(options) {}

    public virtual DbSet<Order> Orders { get; set; }

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    => optionsBuilder.UseSqlServer("Name=ConnectionStrings:BSConnection");

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<Order>(entity =>
            {
                entity.HasKey(e => e.OrderId)
                      .HasName("PK__orders__465962291A616684");

                entity.ToTable("orders", "sales");
 
                entity.Property(e => e.OrderId)
                      .HasColumnName("order_id");
                entity.Property(e => e.CustomerId)
                      .HasColumnName("customer_id");
                entity.Property(e => e.OrderDate)
                      .HasColumnType("date")
                      .HasColumnName("order_date");
                entity.Property(e => e.OrderStatus)
                      .HasColumnName("order_status");
                entity.Property(e => e.RequiredDate)
                      .HasColumnType("date")
                      .HasColumnName("required_date");
                entity.Property(e => e.ShippedDate)
                      .HasColumnType("date")
                      .HasColumnName("shipped_date");
                entity.Property(e => e.StaffId)
                      .HasColumnName("staff_id");
                entity.Property(e => e.StoreId)
                      .HasColumnName("store_id");

                entity.HasOne(d => d.Customer)
                      .WithMany(p => p.Orders)
                      .HasForeignKey(d => d.CustomerId)
                      .OnDelete(DeleteBehavior.Cascade)
                      .HasConstraintName("FK__orders__customer__47DBAE45");

                entity.HasOne(d => d.Staff)
                      .WithMany(p => p.Orders)
                      .HasForeignKey(d => d.StaffId)
                      .OnDelete(DeleteBehavior.ClientSetNull)
                      .HasConstraintName("FK__orders__staff_id__49C3F6B7");

                entity.HasOne(d => d.Store)
                      .WithMany(p => p.Orders)
                      .HasForeignKey(d => d.StoreId)
                      .HasConstraintName("FK__orders__store_id__48CFD27E");
            });
        OnModelCreatingPartial(modelBuilder);
    }
}

Answer 1

Entity Framework 6（不是 ef core 6）允许您对底层关系数据库执行原始 SQL 查询

DbSet.SqlQuery() //querying mapped types
DbContext.Database.SqlQuery() //querying unmapped types
DbContext.Database.ExecuteSqlCommand() //querying unmapped types

映射样本：

using (var context = new BikeStoreContext())
{
    var order = context.Orders
                    .SqlQuery("Select * from Orders where OrderId=@id", new SqlParameter("@id", 1))
                    .FirstOrDefault();
}

未映射的示例：

using (var context = new BikeStoreContext())
{
    //Get OrderDate of DateTime type
    string orderDate = context.Database.SqlQuery<DateTime>("Select OrderDate from Orders where OrderId=1")
                            .FirstOrDefault();

    //or
    string orderDate = context.Database.SqlQuery<DateTime>("Select OrderDate from Orders where OrderId=@id", new SqlParameter("@id", 1))
                            .FirstOrDefault();
}

请记住，这些技巧适用于 Entity Framework 6，而不是 EF Core 6。

https://github.com/dotnet/ef6

https://github.com/dotnet/efcore

/////////////////////////////////////////////////////////////////////////////////////// ////////////////////////////

EF8(EF Core 8) 引入了对使用原始 SQL 查询来查询未映射类型的支持。

var orders = await context
    .Database
    .SqlQuery<Question>(
        $"SELECT * FROM Orders")
    .ToListAsync();