实体框架添加新实体

Question

我无法在表格中插入记录

public class KPITable
{

    [Key]        
    public int Id { get; set; }
    public string Name { get; set; }
    public string Query { get; set; }
    public string TableName { get; set; }
}

public class KPITableMap : EntityTypeConfiguration<KPITable>
{
    public KPITableMap()
    {
        ToTable("EIS_KPI", AppUtility.EISMDBSchemaName);
        Property(t => t.Id).HasColumnName("KPI_ID");           
        Property(t => t.Name).HasColumnName("NAME").HasMaxLength(20);
        Property(t => t.Query).HasColumnName("QUERY").HasMaxLength(20);
        Property(t => t.TableName).HasColumnName("TABLE_NAME").HasMaxLength(20);

    }
}

当我尝试添加新实体时，我收到错误

  

为不可为空的成员返回了null存储生成的值   'Id'类型'EISM.Database.Models.KPITable

var newEntity = new KPITable();
newEntity.Id = 55;
                newEntity.Name = data.Name;
                newEntity.Query = data.Query;
                newEntity.TableName = data.TableName;
_dbContext.KPIs.Attach(newEntity);
                _dbContext.Entry(newEntity).State = EntityState.Added;
                _dbContext.SaveChanges();

Answer 1

这解决了我的问题

[Key]     
[DatabaseGenerated(DatabaseGeneratedOption.None)]
public int Id { get; set; }

或者你可以删除这一行

[DatabaseGenerated(DatabaseGeneratedOption.Computed)]

Answer 2

这应该有效：

var newEntity = new KPITable();
newEntity.Id = 55;
                newEntity.Name = data.Name;
                newEntity.Query = data.Query;
                newEntity.TableName = data.TableName;
_dbContext.KPIs.AddObject(newEntity);
_dbContext.SaveChanges();

附加适用于现有实体（当它们被分离时，或者当您想要将它附加到另一个实体时）。

AddObject适用于新实体。