我要做什么：
我正在尝试保存一个候选人的多个描述，并且每个描述都应在“描述”视图中相应显示。
这是我的控制人：
public IActionResult CandidateHistory(int Id)
{
using (var applicationcontext = new ApplicationContext())
{
var candidate =
applicationcontext.Candidates.AsNoTracking().Include(q =>
q.DescriptionList).Single(q => q.Id == Id);
if (candidate == null)
{
return NotFound();
}
applicationcontext.Candidates.Add(candidate);
return View(candidate);
}
}
[HttpPost, ActionName("CandidateHistory")]
[ValidateAntiForgeryToken]
public IActionResult CandidateHistoryPost([Bind("Description, Title,
DateOfDescription, Saving")]Candidate candidate, int Id)
{
try
{
if (ModelState.IsValid)
{
using (var applicationContext = new ApplicationContext())
{
var candidates =
applicationContext.Candidates.AsNoTracking().Include(q =>
q.DescriptionList).Single(q => q.Id == Id);
//candidates.Description = candidate.Description;
//candidates.Saving = candidate.Saving;
//candidates.Title = candidate.Title;
//candidates.DateOfDescription =
candidate.DateOfDescription;
//candidate.DescriptionList.Add(candidates);
var guardar = candidate;
candidates.Saving = guardar.Saving;
candidates.Title = guardar.Title;
candidates.Description = guardar.Description;
candidates.DateOfDescription = guardar.DateOfDescription;
candidate = candidates;
candidates.DescriptionList.Add(candidate);
candidate.DescriptionList = candidates.DescriptionList;
applicationContext.Candidates.Add(candidate);
applicationContext.SaveChanges();
return RedirectToAction("CandidateHistory");
}
}
}
catch (DbUpdateException /* ex */)
{
//Log the error (uncomment ex variable name and write a log.
ModelState.AddModelError("", "Unable to save changes. " +
"Try again, and if the problem persists " +
"see your system administrator.");
}
return View(candidate);
}
这也是我的候选人榜样：
public class Candidate : BaseEntity
{
public int Id { get; set; }
public string Name { get; set; }
public int Number { get; set; }
public string ProfileText { get; set; }
public Byte[] CV { get; set; }
public string CVNAME { get; set; }
public List<Profile> ProfileList { get; set; }
public String Description { get; set; }
public Boolean Saving { get; set; }
public string Title { get; set; }
public DateTime DateOfDescription { get; set; }
public List<Candidate> DescriptionList { get; set; }
public Candidate()
{
DescriptionList = new List<Candidate>();
}
}
这是我的视图：
@model HCCBPOHR.Data.Candidate
@{
ViewData["Title"] = "CandidateHistory";
}
<h2>Canidate - @Model.Name</h2>
<label>History</label>
<hr />
<div class="panel panel-default">
<div class="panel-heading">
<i class="fa fa-clock-o fa-fw"></i> History Of @Model.Name
</div>
<div class="panel-body">
@foreach (var Description in Model.DescriptionList)
{
@if (Model.Saving == true)
{
<ul class="timeline">
<li class="timeline">
<div class="timeline-badge">
<i class="fa fa-check"></i>
</div>
<div class="timeline-panel">
<div class="timeline-heading">
<h4 class="timeline-title">@Model.Title</h4>
<p>
<small class="text-muted"><i class="fa fa-
clock-o"></i> @Model.DateOfDescription.ToShortDateString()</small>
</p>
</div>
<div class="timeline-body">
<p>@Model.Description</p>
</div>
</div>
</li>
</ul>
}
@if (Model.Saving == false)
{
<ul class="timeline">
<li class="timeline-inverted">
<div class="timeline-badge">
<i class="fa fa-check"></i>
</div>
<div class="timeline-panel">
<div class="timeline-heading">
<h4 class="timeline-title">Title</h4>
<p>
<small class="text-muted"><i class="fa fa-
clock-o"></i> @Model.DateOfDescription.ToShortDateString()</small>
</p>
</div>
<div class="timeline-body">
<p>@Model.Description</p>
</div>
</div>
</li>
</ul>
}
}
</div>
</div>
<button type="button" class="btn btn-primary" data-toggle="modal" data-
target="#exampleModal" data-whatever="@Model.Saving"> Add History
Description</button>
<div class="modal fade" id="exampleModal" tabindex="-1" role="dialog"
aria-
labelledby="exampleModalLabel" aria-hidden="true">
<div class="modal-dialog" role="document">
<div class="modal-content">
<div class="modal-body">
<form asp-action="CandidateHistory">
<div asp-validation-summary="ModelOnly" class="text-danger">
</div>
<div class="form-group">
<label asp-for="Title" class="control-label"></label>
<input asp-for="Title" class="form-control" />
<span asp-validation-for="Title" class="text-danger">
</span>
</div>
<div class="form-group">
<label asp-for="Description" class="control-label">
</label>
<input asp-for="Description" class="form-control" />
<span asp-validation-for="Description" class="text-
danger"></span>
</div>
<div class="form-group">
<label>Selects</label>
<select asp-for="Saving" class="form-control">
<option value="false">Candidate </option>
<option value="true">Hitachi</option>s
</select>
</div>
<div class="form-group">
<label asp-for="DateOfDescription" class="form-group" >
</label>
<input asp-for="DateOfDescription" class="form-group" />
</div>
<div class="form-group">
<input type="submit" value="Create" class="btn btn-
default" />
</div>
</form>
</div>
<div class="modal-footer">
<button type="button" class="btn btn-secondary" data-
dismiss="modal">Close</button>
</div>
</div>
</div>
</div>
捕获方法抛出异常，我不明白为什么。
catch (DbUpdateException /* ex */)
{
//Log the error (uncomment ex variable name and write a log.
ModelState.AddModelError("", "Unable to save changes. " +
"Try again, and if the problem persists " +
"see your system administrator.");
}
例外是：
{Microsoft.EntityFrameworkCore.DbUpdateException：更新条目时发生错误。有关详细信息，请参见内部异常。 ---> System.Data.SqlClient.SqlException：当IDENTITY_INSERT设置为OFF时，无法为表“候选对象”中的标识列插入显式值。 在System.Data.SqlClient.SqlConnection.OnError（SqlException异常，布尔值breakConnection，操作
1 wrapCloseInAction) at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection, Action1 wrapCloseInAction） 在System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning（TdsParserStateObject stateObj，布尔调用方HasConnectionLock，布尔asyncClose） 在System.Data.SqlClient.TdsParser.TryRun（RunBehavior runBehavior，SqlCommand cmdHandler，SqlDataReader dataStream，BulkCopySimpleResultSet bulkCopyHandler，TdsParserStateObject stateObj，Boolean和dataReady） 在System.Data.SqlClient.SqlDataReader.TryConsumeMetaData（） 在System.Data.SqlClient.SqlDataReader.get_MetaData（） 在System.Data.SqlClient.SqlCommand.FinishExecuteReader（SqlDataReader ds，RunBehavior runBehavior，字符串resetOptionsString） 在System.Data.SqlClient.SqlCommand.RunExecuteReaderTds（CommandBehavior cmdBehavior，RunBehavior runBehavior，Boolean returnStream，Boolean异步，Int32超时，Task＆task，Boolean asyncWrite，SqlDataReader ds） 在System.Data.SqlClient.SqlCommand.RunExecuteReader处（CommandBehavior cmdBehavior，RunBehavior runBehavior，布尔值returnStream，TaskCompletionSource1 completion, Int32 timeout, Task& task, Boolean asyncWrite, String method) at System.Data.SqlClient.SqlCommand.ExecuteReader(CommandBehavior behavior) at System.Data.SqlClient.SqlCommand.ExecuteDbDataReader(CommandBehavior behavior) at Microsoft.EntityFrameworkCore.Storage.Internal.RelationalCommand.Execute(IRelationalConnection connection, DbCommandMethod executeMethod, IReadOnlyDictionary2个参数值） 在Microsoft.EntityFrameworkCore.Storage.Internal.RelationalCommand.ExecuteReader（IRelationalConnection连接，IReadOnlyDictionary2 parameterValues) at Microsoft.EntityFrameworkCore.Update.ReaderModificationCommandBatch.Execute(IRelationalConnection connection) --- End of inner exception stack trace --- at Microsoft.EntityFrameworkCore.Update.ReaderModificationCommandBatch.Execute(IRelationalConnection connection) at Microsoft.EntityFrameworkCore.Update.Internal.BatchExecutor.Execute(Tuple2个参数）处 在Microsoft.EntityFrameworkCore.Storage.Internal.SqlServerExecutionStrategy.Execute [TState，TResult]（TState状态，Func3 operation, Func3验证成功）处 在Microsoft.EntityFrameworkCore.Update.Internal.BatchExecutor.Execute（IEnumerable1 commandBatches, IRelationalConnection connection) at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.StateManager.SaveChanges(IReadOnlyList1个条目要保存） 在Microsoft.EntityFrameworkCore.ChangeTracking.Internal.StateManager.SaveChanges（Boolean acceptAllChangesOnSuccess） 在Microsoft.EntityFrameworkCore.DbContext.SaveChanges（Boolean acceptAllChangesOnSuccess） 在C：\ Users \ 137258 \ Documents \ hccbpohr \ src \ Web \ Controllers \ HomeController.cs：line 628}中的HCCBPOHR.Web.Controllers.HomeController.CandidateHistoryPost（候选候选人，Int32 Id）处
答案 0 :(得分：0)
在例外情况下，它表示An error occurred while updating the entries. See the inner exception for details. ---> System.Data.SqlClient.SqlException: Cannot insert explicit value for identity column in table 'Candidates' when IDENTITY_INSERT is set to OFF.
这意味着在SQL中，您无法将主键的值设置为身份键（例如IDENTITY(1,1)）插入表中。根据您的情况，密钥很可能是ID。在c＃代码中，在模型类的字段上添加一个属性。
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int Id{ get; set; }