Entity Framework mysterious error - entity-framework

Question

Please help. I don`t understand why from my entity context
var stagesExist = context.WfwDocumentWorkStages
.Any(it => it.Enabled && it.ExecutionId == execution.Id
&& it.Level == execution.Level && it.ResultId == null);
value stagesExist is false
But
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);
value stagesExist is true??

Answer 1

Model:
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; }
}
Mapping
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);
}
}
Result model contains virtual List
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

The problem is this line in your mapping:
this.HasRequired(t => t.WfwEventResult)
You are effectively telling the EF that the associated FK column will never be null (although you've made it int? and have records with null value). Remember that EF uses metadata information when building SQL queries, and in this case I guess the query optimizer decides that this query will never return records (similar to .Where(it => false)) and generates a fake SQL query you see.
Shortly - make sure you always provide the correct information to EF. In this case, change the above to
this.HasOptional(t => t.WfwEventResult)
and you'll see a different (real) query and get a correct results.