EntityFramework.Extensions 6.1 Batch Delete throws “Sequence contains more than one element”

问题

Trying to use EntityFramework.Extensions for Delete and I have a case where I get the error from the title. Here is the scenario:

public class AList
{
    [Key]
    public int Id { get; set; }

    [Column]
    public int XId { get; set; }
}

public abstract class X
{
    [Key]
    public int Id { get; set; }

    public ICollection<AList> TheAList { get; set; }
}

public class Y : X
{
    [Column("TheId")]
    public int? SomeId { get; set; }
}

public class Z : X
{
    [Column("TheId")]
    public int? SomeIdZ { get; set; }
}

This is the mapping:

modelBuilder.Entity<X>()
.HasKey(t => t.Id)
.Map<Y>(t => t.Requires("XType").HasValue(1))
.Map<Z>(t => t.Requires("XType").HasValue(2));

modelBuilder.Entity<X>()
.HasMany(t => t.TheAList)
.WithRequired()
.HasForeignKey(t => t.XId);

And this is what how I'm deleting the row:

db.XTable.Where(t => t.Id == Id).Delete();

What's wrong with my setup? It works fine when I do:

db.AListTable.Where(t => t.XId == Id).Delete();

回答1:

It might be a bug in EntityFramework.Extended, in which case you can:

report the bug (on https://github.com/loresoft/EntityFramework.Extended)
or wait for someone else to do it,
or check out the source code and try to fix it yourself
or use a workaround

possible workarounds:

// not ideal, because object(s) are fetched from db
// I assume that you use the library to prevent this situation.
var existing = db.XTable.SingleOrDefault(t => t.Id == Id);
if (existing != null)
   db.XTable.Remove(existing);

// without fetching the object from db
db.Database.ExecuteSqlCommand("DELETE [XTable] WHERE Id = @Id", new SqlParameter("Id", Id));

Either way, the situation sucks a bit ;)

来源：https://stackoverflow.com/questions/23386698/entityframework-extensions-6-1-batch-delete-throws-sequence-contains-more-than

标签

asp.net-mvc-5

entity-framework-6.1