把断点放在你的[HttpPost]方法上，检查什么值被传递给Id属性。如果它不为零，则会发生此错误。

This occurs when you have a (Primary key) column that is not set to Is Identity to true in SQL and you don't pass explicit value thereof during insert. It will take the first row, then you wont be able to insert the second row, the error will pop up. This can be corrected by adding this line of code [DatabaseGenerated(DatabaseGeneratedOption.Identity)] in your PrimaryKey column and make sure its set to a data type int. If the column is the primary key and is set to IsIDentity to true in SQL there is no need for this line of code [DatabaseGenerated(DatabaseGeneratedOption.Identity)] this also occurs when u have a column that is not the primary key, in SQL that is set to Is Identity to true, and in your EF you did not add this line of code [DatabaseGenerated(DatabaseGeneratedOption.Identity)]

首先转到所需的表名

步骤2 ->右击表名

选择设计

单击列名

步骤5)进入列属性，然后将No设置为Identity Specification

[注意:插入到显式值后，如果你想，你可以恢复到标识规范为true，然后它会再次生成值]

如果你使用SQL server管理studio你可以使用下面的方法

步骤1) 步骤2)

您正在为OperationId插入值，这是一个标识列。

您可以像这样在表上打开标识插入，以便您可以指定自己的标识值。

SET IDENTITY_INSERT Table1 ON

INSERT INTO Table1
/*Note the column list is REQUIRED here, not optional*/
            (OperationID,
             OpDescription,
             FilterID)
VALUES      (20,
             'Hierachy Update',
             1)

SET IDENTITY_INSERT Table1 OFF 

使用实体框架与这样的模型有同样的问题(我简化了原始代码):

public class Pipeline
{
  public Pipeline()
  {
     Runs = new HashSet<Run>();
  }

  public int Id {get; set;}
  public ICollection<Run> Runs {get;set;}
}

public class Run
{
  public int Id {get; set;}
  public int RequestId {get; set;}
  public Pipeline Pipeline {get;set;}
}

运行与管道有多对1的关系(一个管道可以运行多次)

在我的RunService中，我注入了dbcontext作为上下文。DbContext有一个Runs DbSet。我在RunService中实现了这个方法:

public async Task<Run> CreateAndInit(int requestId, int pplId)
{
  Pipeline pipeline = await pipelineService.Get(pplId).FirstOrDefaultAsync().ConfigureAwait(false);
  Run newRun = new Run {RequestId = requestId, Pipeline = pipeline};
  context.Runs.Add(newRun);
  await context.SaveChangesAsync().ConfigureAwait(false); // got exception in this line
  return newRun;
}

当方法执行时，我得到了这个异常:

Exception has occurred: CLR/Microsoft.EntityFrameworkCore.DbUpdateException
Exception thrown: 'Microsoft.EntityFrameworkCore.DbUpdateException' in System.Private.CoreLib.dll: 'An error occurred while updating the entries. See the inner exception for details.'
 Inner exceptions found, see $exception in variables window for more details.
 Innermost exception     Microsoft.Data.SqlClient.SqlException : Cannot insert explicit value for identity column in table 'Pipelines' when IDENTITY_INSERT is set to OFF.

对我来说，解决方案是将对象和关系的创建分开

public async Task<Run> CreateAndInit(int requestId, int pplId)
{
  Pipeline pipeline = await pipelineService.Get(pplId).FirstOrDefaultAsync().ConfigureAwait(false);
  Run newRun = new Run {RequestId = requestId};
  context.Runs.Add(newRun);
  newRun.Pipeline = pipeline; // set the relation separately
  await context.SaveChangesAsync().ConfigureAwait(false); // no exception
  return newRun;
}

如果您使用Interface并以通用方式实现savechanges方法，则会出现使用非类型化DBContext或DBSet的问题

如果这是您的情况，我建议使用强类型的dbcontext

MyDBContext.MyEntity.Add(mynewObject)

那么，保存更改就可以了