添加合成后，我无法保存记录

问题描述：

下面的代码工作正常，直到添加组合键。添加复合键后，我只能编辑现有的记录，无法添加新的记录。我想Code和CompanyId列成为组合键。添加合成后，我无法保存记录

这是错误：

Cannot insert explicit value for identity column in table 'CostCenters' when IDENTITY_INSERT is set to OFF.

寻找SO解决方案后及以下线路添加（仍然没有进展）：

Property(c => c.CompanyId).HasDatabaseGeneratedOption(DatabaseGeneratedOption.None);

型号：

public class CostCenter 
{ 
    public int Id { get; set; } 
    public string Code { get; set; } 
    public string Description { get; set; } 
    [ScriptIgnore(ApplyToOverrides = true)] 
    public virtual Company Company { get; set; } 
    public int CompanyId { get; set; } 
}

FluentAPI：

public CostCenterConfiguration() 
    { 
     HasKey(c => new { c.Code, c.CompanyId }); 
     Property(c => c.CompanyId) 
     .HasDatabaseGeneratedOption(DatabaseGeneratedOption.None); 
     Property(c => c.Code) 
     .IsRequired() 
     .HasMaxLength(255); 
     Property(c => c.Description) 
     .HasMaxLength(1200); 
     HasRequired(c => c.Company) 
     .WithMany(c => c.CostCenters) 
     .HasForeignKey(c => c.CompanyId) 
     .WillCascadeOnDelete(false); 
    }

控制器：

public ActionResult Save(CostCenter costcenter) 
    { 
     try 
     { 
      if (costcenter.Id == 0) 
       _context.CostCenters.Add(costcenter); 
      else 
      { 
       var costcenterInDb = _context.CostCenters.Single(c => c.Id == costcenter.Id); 
       costcenterInDb.Code = costcenter.Code; 
       costcenterInDb.Description = costcenter.Description; 
       costcenterInDb.CompanyId = costcenter.CompanyId; 
      } 
      _context.SaveChanges(); 
      return RedirectToAction("Index", "CostCenters"); 
     } 
     catch (System.Data.Entity.Validation.DbEntityValidationException ex) 
     { 
      var error = ex.EntityValidationErrors.First().ValidationErrors.First(); 
      this.ModelState.AddModelError(error.PropertyName, error.ErrorMessage); 
      return View("CostCenterForm"); 
     } 
     catch (DbUpdateException e) when ((e?.InnerException?.InnerException as System.Data.SqlClient.SqlException)?.Number == 2601) 
     { 
      this.ModelState.AddModelError("Code", "Item with such '" + costcenter.Code + "' already exist"); 
      return View("CostCenterForm"); 
     } 
    }

错误消息很明显，您尝试在IDENTITY_INSERT设置为打开时将值插入标识列。 – Sami

如何使用FluentAPI设置'on'？通过启用identity_insert将解决我的问题？ –

阅读[this]（https://docs.microsoft.com/en-us/sql/t-sql/statements/set-identity-insert-transact-sql） – Sami

答

Cannot insert explicit value for identity column in table 'CostCenters' when IDENTITY_INSERT is set to OFF.

错误信息是明确的也有帮助，你试图将值插入到IDENTITY列，而IDENTITY_INSERT设置为OFF。

我建议删除该值，让SQL服务器做的工作，但如果你坚持要插入值，那么你应该设置IDENTITY_INSERT到ON并再次将其设置为OFF完成刚过：

SET IDENTITY_INSERT Schema.TableName ON; 
GO 
-- do your insert 
SET IDENTITY_INSERT Schema.TableName OFF; 
GO

添加合成后，我无法保存记录

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