Asp.net mvc 在MVC asp.net中保存多对多
我读了很多关于MVC的书。但到目前为止，还没有明确的答案如何处理多对多关系，因为这些教程的许多结果都有相同的错误。Asp.net mvc 在MVC asp.net中保存多对多,asp.net-mvc,ado.net,entity-framework-6,Asp.net Mvc,Ado.net,Entity Framework 6,我读了很多关于MVC的书。但到目前为止，还没有明确的答案如何处理多对多关系，因为这些教程的许多结果都有相同的错误。 我使用的是数据库优先的方法，我的应用程序应该添加用户，在添加用户时，我应该有一个来自角色的列表，我可以将这些角色添加到该用户，或者相反，我可以有带有用户列表和编辑的角色，正如我们所知，当我向ado.net添加带有中断表的数据库时，关系将是多对多。 我已成功添加角色列表，但当我按save时，出现了空引用异常。 这是我的代码： 首先是自定义视图： namespace UserMangm
我使用的是数据库优先的方法，我的应用程序应该添加用户，在添加用户时，我应该有一个来自角色的列表，我可以将这些角色添加到该用户，或者相反，我可以有带有用户列表和编辑的角色，正如我们所知，当我向ado.net添加带有中断表的数据库时，关系将是多对多。
我已成功添加角色列表，但当我按save时，出现了空引用异常。
这是我的代码：
首先是自定义视图：
namespace UserMangment.ViewModel
{
public class RolesViewMode
{
public tab_OnlineUsers OnlineUsers { get; set; }
public IEnumerable<SelectListItem> AllRolesnames { get; set; }
private List<string> _selectedRolesname;
public List<string> SelectedRoleTags
{
get
{
if (_selectedRolesname == null)
{
_selectedRolesname = OnlineUsers.tab_OnlineRoles.Select(m => m.Id).ToList();
}
return _selectedRolesname;
}
set { _selectedRolesname = value; }
}
}
}
@model UserMangment.ViewModel.RolesViewMode
@{
ViewBag.Title = "Create";
}
<h2>Create</h2>
@using (Html.BeginForm())
{
@Html.AntiForgeryToken()
<div class="form-horizontal">
<h4>tab_OnlineUsers</h4>
<hr />
@Html.ValidationSummary(true, "", new { @class = "text-danger" })
<div class="form-group">
@Html.LabelFor(model => model.OnlineUsers.Id, htmlAttributes: new { @class = "control-label col-md-2" })
<div class="col-md-10">
@Html.EditorFor(model =>model.OnlineUsers.Id, new { htmlAttributes = new { @class = "form-control" } })
@Html.ValidationMessageFor(model =>model.OnlineUsers.Id, "", new { @class = "text-danger" })
</div>
</div>
<div class="form-group">
@Html.LabelFor(model =>model.OnlineUsers.Email, htmlAttributes: new { @class = "control-label col-md-2" })
<div class="col-md-10">
@Html.EditorFor(model =>model.OnlineUsers.Email, new { htmlAttributes = new { @class = "form-control" } })
@Html.ValidationMessageFor(model =>model.OnlineUsers.Email, "", new { @class = "text-danger" })
</div>
</div>
<div class="form-group">
@Html.LabelFor(model =>model.OnlineUsers.EmailConfirmed, htmlAttributes: new { @class = "control-label col-md-2" })
<div class="col-md-10">
<div class="checkbox">
@Html.EditorFor(model =>model.OnlineUsers.EmailConfirmed)
@Html.ValidationMessageFor(model =>model.OnlineUsers.EmailConfirmed, "", new { @class = "text-danger" })
</div>
</div>
</div>
<div class="form-group">
@Html.LabelFor(model =>model.OnlineUsers.PasswordHash, htmlAttributes: new { @class = "control-label col-md-2" })
<div class="col-md-10">
@Html.EditorFor(model =>model.OnlineUsers.PasswordHash, new { htmlAttributes = new { @class = "form-control" } })
@Html.ValidationMessageFor(model =>model.OnlineUsers.PasswordHash, "", new { @class = "text-danger" })
</div>
</div>
<div class="form-group">
@Html.LabelFor(model =>model.OnlineUsers.SecurityStamp, htmlAttributes: new { @class = "control-label col-md-2" })
<div class="col-md-10">
@Html.EditorFor(model =>model.OnlineUsers.SecurityStamp, new { htmlAttributes = new { @class = "form-control" } })
@Html.ValidationMessageFor(model =>model.OnlineUsers.SecurityStamp, "", new { @class = "text-danger" })
</div>
</div>
<div class="form-group">
@Html.LabelFor(model =>model.OnlineUsers.PhoneNumber, htmlAttributes: new { @class = "control-label col-md-2" })
<div class="col-md-10">
@Html.EditorFor(model =>model.OnlineUsers.PhoneNumber, new { htmlAttributes = new { @class = "form-control" } })
@Html.ValidationMessageFor(model =>model.OnlineUsers.PhoneNumber, "", new { @class = "text-danger" })
</div>
</div>
<div class="form-group">
@Html.LabelFor(model =>model.OnlineUsers.PhoneNumberConfirmed, htmlAttributes: new { @class = "control-label col-md-2" })
<div class="col-md-10">
<div class="checkbox">
@Html.EditorFor(model =>model.OnlineUsers.PhoneNumberConfirmed)
@Html.ValidationMessageFor(model =>model.OnlineUsers.PhoneNumberConfirmed, "", new { @class = "text-danger" })
</div>
</div>
</div>
<div class="form-group">
@Html.LabelFor(model =>model.OnlineUsers.TwoFactorEnabled, htmlAttributes: new { @class = "control-label col-md-2" })
<div class="col-md-10">
<div class="checkbox">
@Html.EditorFor(model =>model.OnlineUsers.TwoFactorEnabled)
@Html.ValidationMessageFor(model =>model.OnlineUsers.TwoFactorEnabled, "", new { @class = "text-danger" })
</div>
</div>
</div>
<div class="form-group">
@Html.LabelFor(model =>model.OnlineUsers.LockoutEndDateUtc, htmlAttributes: new { @class = "control-label col-md-2" })
<div class="col-md-10">
@Html.EditorFor(model =>model.OnlineUsers.LockoutEndDateUtc, new { htmlAttributes = new { @class = "form-control" } })
@Html.ValidationMessageFor(model =>model.OnlineUsers.LockoutEndDateUtc, "", new { @class = "text-danger" })
</div>
</div>
<div class="form-group">
@Html.LabelFor(model =>model.OnlineUsers.LockoutEnabled, htmlAttributes: new { @class = "control-label col-md-2" })
<div class="col-md-10">
<div class="checkbox">
@Html.EditorFor(model =>model.OnlineUsers.LockoutEnabled)
@Html.ValidationMessageFor(model =>model.OnlineUsers.LockoutEnabled, "", new { @class = "text-danger" })
</div>
</div>
</div>
<div class="form-group">
@Html.LabelFor(model =>model.OnlineUsers.AccessFailedCount, htmlAttributes: new { @class = "control-label col-md-2" })
<div class="col-md-10">
@Html.EditorFor(model =>model.OnlineUsers.AccessFailedCount, new { htmlAttributes = new { @class = "form-control" } })
@Html.ValidationMessageFor(model =>model.OnlineUsers.AccessFailedCount, "", new { @class = "text-danger" })
</div>
</div>
<div class="form-group">
@Html.LabelFor(model =>model.OnlineUsers.UserName, htmlAttributes: new { @class = "control-label col-md-2" })
<div class="col-md-10">
@Html.EditorFor(model =>model.OnlineUsers.UserName, new { htmlAttributes = new { @class = "form-control" } })
@Html.ValidationMessageFor(model =>model.OnlineUsers.UserName, "", new { @class = "text-danger" })
</div>
</div>
<div class="form-group">
@Html.LabelFor(model => model.AllRolesnames, "Roles Name", new { @class = "control-label col-md-2" })
<div class="col-md-10">
@Html.ListBoxFor(m => m.SelectedRoleTags, Model.AllRolesnames)
</div>
</div>
<div class="form-group">
<div class="col-md-offset-2 col-md-10">
<input type="submit" value="Create" class="btn btn-default" />
</div>
</div>
</div>
}
<div>
@Html.ActionLink("Back to List", "Index")
</div>
}
@model usermanagement.ViewModel.RolesViewMode
@{
ViewBag.Title=“创建”；
}
创造
@使用（Html.BeginForm（））
{
@Html.AntiForgeryToken（）
tab_在线用户
@Html.ValidationSummary（true，“，new{@class=“text danger”}）
@LabelFor（model=>model.OnlineUsers.Id，htmlAttributes:new{@class=“controllabel col-md-2”}）
@EditorFor（model=>model.OnlineUsers.Id，new{htmlAttributes=new{@class=“form control”}）
@Html.ValidationMessageFor（model=>model.OnlineUsers.Id，“，new{@class=“text danger”}）
@LabelFor（model=>model.OnlineUsers.Email，htmlAttributes:new{@class=“controllabel col-md-2”}）
@EditorFor（model=>model.OnlineUsers.Email，new{htmlAttributes=new{@class=“form control”}）
@Html.ValidationMessageFor（model=>model.OnlineUsers.Email，“，新{@class=“text danger”}）
@LabelFor（model=>model.OnlineUsers.EmailConfirmed，htmlAttributes:new{@class=“control label col-md-2”}）
@Html.EditorFor（model=>model.OnlineUsers.emailconfirm）
@Html.ValidationMessageFor（model=>model.OnlineUsers.EmailConfirmed，“，new{@class=“text danger”}）
@LabelFor（model=>model.OnlineUsers.PasswordHash，htmlAttributes:new{@class=“controllabel col-md-2”}）
@EditorFor（model=>model.OnlineUsers.PasswordHash，new{htmlAttributes=new{@class=“form control”}）
@Html.ValidationMessageFor（model=>model.OnlineUsers.PasswordHash，“，新的{@class=“text danger”}）
@LabelFor（model=>model.OnlineUsers.SecurityStamp，htmlAttributes:new{@class=“controllabel col-md-2”}）
@EditorFor（model=>model.OnlineUsers.SecurityStamp，new{htmlAttributes=new{@class=“form control”}）
@Html.ValidationMessageFor（model=>model.OnlineUsers.SecurityStamp，“，新的{@class=“text danger”}）
@LabelFor（model=>model.OnlineUsers.PhoneNumber，htmlAttributes:new{@class=“controllabel col-md-2”}）
@EditorFor（model=>model.OnlineUsers.PhoneNumber，new{htmlAttributes=new{@class=“form control”}）
@Html.ValidationMessageFor（model=>model.OnlineUsers.PhoneNumber，“，新的{@class=“text danger”}）
@LabelFor（model=>model.OnlineUsers.phonenumberconfirm，htmlAttributes:new{@class=“control label col-md-2”}）
@Html.EditorFor（model=>model.OnlineUsers.phonenumberconfirm）
@Html.ValidationMessageFor（model=>model.OnlineUsers.PhoneNumberConfirmed，“，new{@class=“text danger”}）
@LabelFor（model=>model.OnlineUsers.twofacturenabled，htmlAttributes:new{@class=“control label col-md-2”}）
@EditorFor（model=>model.OnlineUsers.TwoFactorEnabled）
@Html.ValidationMessageFor（model=>model.OnlineUsers.twofacturenabled，“，new{@class=“text danger”}）
@LabelFor（model=>model.OnlineUsers.LockoutEndDateUtc，htmlAttributes:new{@class=“control label col-md-2”}）
@EditorFor（model=>model.OnlineUsers.LockoutEndDateUtc，new{htmlAttributes=new{@class=“form control”}）
@Html.ValidationMessageFor（model=>model.OnlineUsers.LockoutEndDateUtc，“，new{@class=“text danger”}）
@LabelFor（model=>model.OnlineUsers.LockoutEnabled，htmlAttributes:new{@class=“control label col-md-2”}）
@Html.EditorFor（model=>model.OnlineUsers.LockoutEnabled）
@Html.ValidationMessageFor（model=>model.OnlineUsers.LockoutEnabled，“，新{@class=“text danger”}）
@LabelFor（model=>model.OnlineUsers.AccessFailedCount，htmlAttributes:new{@class=“control label col-md-2”}）
@EditorFor（model=>model.OnlineUsers.AccessFailedCount，new{htmlAttributes=new{@class=“form control”}）
@Html.ValidationMessageFor（model=>model.OnlineUsers.AccessFailedCount，“，新{@class=“text danger”}）
@LabelFor（model=>model.OnlineUsers.UserName，htmlAttributes:new{@class=“controllabel col-md-2”}）
@EditorFor（model=>model.OnlineUsers.UserName，new{htmlAttributes=new{@class=“form control”}）
@Html.ValidationMessageFor（model=>model.OnlineUsers.UserName，“，新{@class=“text danger”}）
@model UserMangment.ViewModel.RolesViewMode
@{
ViewBag.Title = "Create";
}
<h2>Create</h2>
@using (Html.BeginForm())
{
@Html.AntiForgeryToken()
<div class="form-horizontal">
<h4>tab_OnlineUsers</h4>
<hr />
@Html.ValidationSummary(true, "", new { @class = "text-danger" })
<div class="form-group">
@Html.LabelFor(model => model.OnlineUsers.Id, htmlAttributes: new { @class = "control-label col-md-2" })
<div class="col-md-10">
@Html.EditorFor(model =>model.OnlineUsers.Id, new { htmlAttributes = new { @class = "form-control" } })
@Html.ValidationMessageFor(model =>model.OnlineUsers.Id, "", new { @class = "text-danger" })
</div>
</div>
<div class="form-group">
@Html.LabelFor(model =>model.OnlineUsers.Email, htmlAttributes: new { @class = "control-label col-md-2" })
<div class="col-md-10">
@Html.EditorFor(model =>model.OnlineUsers.Email, new { htmlAttributes = new { @class = "form-control" } })
@Html.ValidationMessageFor(model =>model.OnlineUsers.Email, "", new { @class = "text-danger" })
</div>
</div>
<div class="form-group">
@Html.LabelFor(model =>model.OnlineUsers.EmailConfirmed, htmlAttributes: new { @class = "control-label col-md-2" })
<div class="col-md-10">
<div class="checkbox">
@Html.EditorFor(model =>model.OnlineUsers.EmailConfirmed)
@Html.ValidationMessageFor(model =>model.OnlineUsers.EmailConfirmed, "", new { @class = "text-danger" })
</div>
</div>
</div>
<div class="form-group">
@Html.LabelFor(model =>model.OnlineUsers.PasswordHash, htmlAttributes: new { @class = "control-label col-md-2" })
<div class="col-md-10">
@Html.EditorFor(model =>model.OnlineUsers.PasswordHash, new { htmlAttributes = new { @class = "form-control" } })
@Html.ValidationMessageFor(model =>model.OnlineUsers.PasswordHash, "", new { @class = "text-danger" })
</div>
</div>
<div class="form-group">
@Html.LabelFor(model =>model.OnlineUsers.SecurityStamp, htmlAttributes: new { @class = "control-label col-md-2" })
<div class="col-md-10">
@Html.EditorFor(model =>model.OnlineUsers.SecurityStamp, new { htmlAttributes = new { @class = "form-control" } })
@Html.ValidationMessageFor(model =>model.OnlineUsers.SecurityStamp, "", new { @class = "text-danger" })
</div>
</div>
<div class="form-group">
@Html.LabelFor(model =>model.OnlineUsers.PhoneNumber, htmlAttributes: new { @class = "control-label col-md-2" })
<div class="col-md-10">
@Html.EditorFor(model =>model.OnlineUsers.PhoneNumber, new { htmlAttributes = new { @class = "form-control" } })
@Html.ValidationMessageFor(model =>model.OnlineUsers.PhoneNumber, "", new { @class = "text-danger" })
</div>
</div>
<div class="form-group">
@Html.LabelFor(model =>model.OnlineUsers.PhoneNumberConfirmed, htmlAttributes: new { @class = "control-label col-md-2" })
<div class="col-md-10">
<div class="checkbox">
@Html.EditorFor(model =>model.OnlineUsers.PhoneNumberConfirmed)
@Html.ValidationMessageFor(model =>model.OnlineUsers.PhoneNumberConfirmed, "", new { @class = "text-danger" })
</div>
</div>
</div>
<div class="form-group">
@Html.LabelFor(model =>model.OnlineUsers.TwoFactorEnabled, htmlAttributes: new { @class = "control-label col-md-2" })
<div class="col-md-10">
<div class="checkbox">
@Html.EditorFor(model =>model.OnlineUsers.TwoFactorEnabled)
@Html.ValidationMessageFor(model =>model.OnlineUsers.TwoFactorEnabled, "", new { @class = "text-danger" })
</div>
</div>
</div>
<div class="form-group">
@Html.LabelFor(model =>model.OnlineUsers.LockoutEndDateUtc, htmlAttributes: new { @class = "control-label col-md-2" })
<div class="col-md-10">
@Html.EditorFor(model =>model.OnlineUsers.LockoutEndDateUtc, new { htmlAttributes = new { @class = "form-control" } })
@Html.ValidationMessageFor(model =>model.OnlineUsers.LockoutEndDateUtc, "", new { @class = "text-danger" })
</div>
</div>
<div class="form-group">
@Html.LabelFor(model =>model.OnlineUsers.LockoutEnabled, htmlAttributes: new { @class = "control-label col-md-2" })
<div class="col-md-10">
<div class="checkbox">
@Html.EditorFor(model =>model.OnlineUsers.LockoutEnabled)
@Html.ValidationMessageFor(model =>model.OnlineUsers.LockoutEnabled, "", new { @class = "text-danger" })
</div>
</div>
</div>
<div class="form-group">
@Html.LabelFor(model =>model.OnlineUsers.AccessFailedCount, htmlAttributes: new { @class = "control-label col-md-2" })
<div class="col-md-10">
@Html.EditorFor(model =>model.OnlineUsers.AccessFailedCount, new { htmlAttributes = new { @class = "form-control" } })
@Html.ValidationMessageFor(model =>model.OnlineUsers.AccessFailedCount, "", new { @class = "text-danger" })
</div>
</div>
<div class="form-group">
@Html.LabelFor(model =>model.OnlineUsers.UserName, htmlAttributes: new { @class = "control-label col-md-2" })
<div class="col-md-10">
@Html.EditorFor(model =>model.OnlineUsers.UserName, new { htmlAttributes = new { @class = "form-control" } })
@Html.ValidationMessageFor(model =>model.OnlineUsers.UserName, "", new { @class = "text-danger" })
</div>
</div>
<div class="form-group">
@Html.LabelFor(model => model.AllRolesnames, "Roles Name", new { @class = "control-label col-md-2" })
<div class="col-md-10">
@Html.ListBoxFor(m => m.SelectedRoleTags, Model.AllRolesnames)
</div>
</div>
<div class="form-group">
<div class="col-md-offset-2 col-md-10">
<input type="submit" value="Create" class="btn btn-default" />
</div>
</div>
</div>
}
<div>
@Html.ActionLink("Back to List", "Index")
</div>
}