我正在使用框架核心2.0实体的编译查询功能,但即使它没有给出语法错误,当程序运行时,我得到此异常:
“无法解析表达式'值(Microsoft.EntityFrameworkCore.Query.Internal.EntityQueryable`1 [TaskManager.Entities.EntitiesDB.USER])AsNoTracking()。Where(__ conditions)':给定的参数与预期的参数不匹配: “System.Linq.Expressions.TypedParameterExpression”类型的对象无法转换为“System.Linq.Expressions.LambdaExpression”类型。“
我不知道它是什么。我需要帮助。
这是我的存储库的源代码,它显示了这个错误:
/// <summary>
/// Query of user
/// </summary>
/// <param name="_context">context</param>
/// <param name="conditions">conditions for clause "Where"</param>
/// <returns>first task that meets the conditions or null </returns>
private static Func<Context, Func<USER, bool>, Task<UserResponseDTO>>
_getUser = EF.CompileAsyncQuery (
(Context _context, Func<USER, bool> conditions) =>
(conditions == null)?
_context.USER.Select(user =>
new UserResponseDTO {
NAME = user.NAME,
EMAIL = user.EMAIL,
SEQUSER = user.SEQUSER,
DATEREGISTER = user.DATEREGISTER
}
).AsNoTracking().FirstOrDefault ()
:
_context.USER.AsNoTracking()
.Where(conditions).Select(user =>
new UserResponseDTO {
NAME = user.NAME,
EMAIL = user.EMAIL,
SEQUSER = user.SEQUSER,
DATEREGISTER = user.DATEREGISTER
}
).FirstOrDefault ()
);
我的类实现DbContext:
public class Context: DbContext
{
public Context(DbContextOptions<Context> options): base(options){ }
public virtual DbSet<USER> USER { get; set; }
public virtual DbSet<TASK> TASK { get; set; }
protected override void OnModelCreating(ModelBuilder modelBuilder){
#region Sequences
modelBuilder.HasSequence<long>
("S_SEQUSER").StartsAt(1).HasMin(1);
modelBuilder.HasSequence<long>
("S_SEQTASK").StartsAt(1).HasMin(1);
#endregion
#region propeties Mapping
modelBuilder.Entity<USER>()
.Property(u => u.SEQUSER)
.HasDefaultValueSql(" nextval('\"S_SEQUSER\"') ");
modelBuilder.Entity<TASK>()
.Property(u => u.SEQTASK)
.HasDefaultValueSql(" nextval('\"S_SEQTASK\"') ");
modelBuilder.Entity<USER>()
.HasMany(u => u.TASK)
.WithOne(u => u.USER);
#endregion
base.OnModelCreating(modelBuilder);
}
}
我的数据库实体:
/// <summary>
/// query user
/// </summary>
[Table(@"USER")]
public class USER
{
#region Properties
/// <summary>
/// sequence of user
/// </summary>
/// <value></value>
[Key()]
[Column(@"SEQUSER")]
public virtual long SEQUSER { get; set; }
/// <summary>
/// email of user
/// </summary>
/// <value></value>
[Required]
[StringLength(120)]
[Column(@"EMAIL")]
public virtual string EMAIL { get; set; }
/// <summary>
/// password of user
/// </summary>
/// <value></value>
[Required]
[StringLength(15)]
[Column(@"PASSWORD")]
public virtual string PASSWORD { get; set; }
/// <summary>
/// name of user
/// </summary>
/// <value></value>
[Required]
[StringLength(120)]
[Column(@"NAME")]
public virtual string NAME { get; set; }
/// <summary>
/// date of user was registered
/// </summary>
/// <value></value>
[Column(@"DATEREGISTER")]
public virtual DateTime DATEREGISTER { get; set; }
/// <summary>
/// last acess of user in application
/// </summary>
/// <value></value>
[Column(@"LASTACESS")]
public virtual DateTime LASTACESS { get; set; }
/// <summary>
/// list of task
/// </summary>
/// <value></value>
[InverseProperty("USER")]
public virtual List<TASK> TASK { get; set; }
#endregion
}
有人可以帮我一把吗?
试着打破它。
从一个简单的测试用例开始(比如一些虚拟new UserResponseDTO
),然后尝试一个简单的静态选择(选择一个特定的用户),然后添加if / else条件并尝试使用和不使用conditions
,然后添加一个简单的静态选择到你的首先是if / else分支,然后对第二个分支执行相同操作,直到找到您现在的语句。
您也可以先执行select(不使用if / else),以检查您的问题是否在Context定义中。也许在包含" nextval('\"S_SEQUSER\"') "
或" nextval('\"S_SEQTASK\"') "
的其中一行中。顺便问一下:为什么这里的空间?
介于两者之间,会出现问题。不同的是:现在你知道在哪里;-)
肯定写一个单元测试。通常只需单击鼠标右键即可。