实体框架神秘错误

Question

请帮忙。我不`吨明白，为什么从我的实体上下文

var stagesExist = context.WfwDocumentWorkStages 
    .Any(it => it.Enabled && it.ExecutionId == execution.Id 
    && it.Level == execution.Level && it.ResultId == null); 

值stagesExist是假 但

var stages = context.WfwDocumentWorkStages.Where(it => it.Enabled 
    && it.ExecutionId == execution.Id 
    && it.Level == execution.Level).ToList(); 
bool stagesExist = stages.Any(it=>it.ResultId == null); 

值stagesExist是真实的？

Answer 1

型号：

public partial class WfwDocumentWorkScheme : EnabledEntity 
{ 
    public WfwDocumentWorkScheme() 
    { 
     this.WfwExecutionEvents = new List<WfwExecutionEvent>(); 
    } 

    public int ExecutionId { get; set; } 
    public int Level { get; set; } 
    public int? RoleId { get; set; } 
    public string CoordinatorSid { get; set; } 
    public DateTimeOffset? Date { get; set; } 
    public int? ResultId { get; set; } 
    public string Comment { get; set; } 
    public virtual Employee Coordinator { get; set; } 
    public virtual EmployeeRole EmployeeRole { get; set; } 
    public virtual WfwEventResult WfwEventResult { get; set; } 
    public virtual WfwDocumentExecution WfwDocumentExecution { get; set; } 
    public virtual ICollection<WfwExecutionEvent> WfwExecutionEvents { get; set; } 
} 

映射

public class WfwDocumentWorkSchemeMap : EntityTypeConfiguration<WfwDocumentWorkScheme> 
{ 
    public WfwDocumentWorkSchemeMap() 
    { 
     // Primary Key 
     this.HasKey(t => t.Id); 

     // Properties 
     this.Property(t => t.CoordinatorSid) 
      .HasMaxLength(46); 

     // Table & Column Mappings 
     this.ToTable("WfwDocumentWorkSchemes"); 
     this.Property(t => t.Id).HasColumnName("Id"); 
     this.Property(t => t.ExecutionId).HasColumnName("ExecutionId"); 
     this.Property(t => t.Level).HasColumnName("Level"); 
     this.Property(t => t.RoleId).HasColumnName("RoleId"); 
     this.Property(t => t.CoordinatorSid).HasColumnName("CoordinatorSid"); 
     this.Property(t => t.Date).HasColumnName("Date"); 
     this.Property(t => t.ResultId).HasColumnName("ResultId"); 
     this.Property(t => t.Comment).HasColumnName("Comment"); 
     this.Property(t => t.Enabled).HasColumnName("Enabled"); 

     // Relationships 
     this.HasRequired(t => t.Coordinator) 
      .WithMany(t => t.WfwDocumentWorkSchemes) 
      .HasForeignKey(d => d.CoordinatorSid); 
     this.HasRequired(t => t.WfwDocumentExecution) 
      .WithMany(t => t.WfwDocumentWorkSchemes) 
      .HasForeignKey(d => d.ExecutionId); 
     this.HasRequired(t => t.WfwEventResult) 
      .WithMany(t => t.WfwDocumentWorkSchemes) 
      .HasForeignKey(d => d.ResultId); 
     this.HasOptional(t => t.EmployeeRole) 
      .WithMany(t => t.WfwDocumentWorkSchemes) 
      .HasForeignKey(d => d.RoleId); 
    } 
} 

结果模型包含虚拟目录

public class WfwEventResult : EnabledEntity 
{ 
    public WfwEventResult() 
    { 
     this.WfwExecutionEvents = new List<WfwExecutionEvent>(); 
     this.WfwDocumentWorkSchemes = new List<WfwDocumentWorkScheme>(); 
    } 

    public string Name { get; set; } 
    public string Description { get; set; } 
    public bool Success { get; set; } 
    public virtual ICollection<WfwExecutionEvent> WfwExecutionEvents { get; set; } 
    public virtual ICollection<WfwDocumentWorkScheme> WfwDocumentWorkSchemes { get; set; } 
} 

Answer 2

和SQL事件探查器显示此查询

SELECT 
CASE WHEN (EXISTS (SELECT 
    1 AS [C1] 
    FROM (SELECT 1 AS X) AS [SingleRowTable2] 
    WHERE 1 = 0 
)) THEN cast(1 as bit) ELSE cast(0 as bit) END AS [C1] 
FROM (SELECT 1 AS X) AS [SingleRowTable1] 

为什么实体框架不工作正确？

Answer 3

的问题是这条线在映射：

this.HasRequired(t => t.WfwEventResult) 

就相当于告诉了EF的相关FK列将永远null（尽管你已经与null值使其int?，并有记录） 。请记住，EF在构建SQL查询时使用元数据信息，在这种情况下，我猜查询优化器会决定此查询永远不会返回记录（类似于.Where(it => false)）并生成您看到的假SQL查询。

不久 - 确保您始终向EF提供正确的信息。在这种情况下，上述改变

this.HasOptional(t => t.WfwEventResult) 

，你会看到一个不同的（真正）查询并得到正确的结果。