Asp.net core 如何在具有模型继承的ASP.Net核心Razor页面中使用DisplayTemplates？_Asp.net Core_Display Templates

Asp.net core 如何在具有模型继承的ASP.Net核心Razor页面中使用DisplayTemplates？

asp.net-core

Asp.net core 如何在具有模型继承的ASP.Net核心Razor页面中使用DisplayTemplates？,asp.net-core,display-templates,Asp.net Core,Display Templates,试图让ASP.NETCore2.2中的DisplayTemplates处理从类似于此问题的基类继承的类 PrincipalDisplayTemplate用于列表中的所有项目，我缺少什么 PageModel public class IndexModel : PageModel { public List<Principal> Principals { get; set; } = new List<Principal>(); public void OnG

试图让ASP.NETCore2.2中的DisplayTemplates处理从类似于此问题的基类继承的类

Principal

DisplayTemplate用于列表中的所有项目，我缺少什么

PageModel

public class IndexModel : PageModel
{
    public List<Principal> Principals { get; set; } = new List<Principal>();

    public void OnGet()
    {
        Principals.Add(new Principal { Id = 1, Name = "Principal 1" });
        Principals.Add(new UserPrincipal { Id = 1, Name = "User 1", Age = 30 });
        Principals.Add(new GroupPrincipal { Id = 1, Name = "Group 1", Members = 5 });
        Principals.Add(new UserPrincipal { Id = 1, Name = "User 2", Age = 40 });
        Principals.Add(new GroupPrincipal { Id = 1, Name = "Group 2", Members = 3 });
    }
}

public class Principal
{
    public int Id { get; set; }
    public string Name { get; set; }
}

public class UserPrincipal : Principal
{
    public int Age { get; set; }
}

public class GroupPrincipal : Principal
{
    public int Members { get; set; }
}

@model Principal
<div>
    <h4>Principal</h4>
    @Model.Name
</div>

@model UserPrincipal
<div>
    <h4>User</h4>
    @Model.Name, Age @Model.Age
</div>

@model GroupPrincipal
<div>
    <h4>Group</h4>
    @Model.Name, Members @Model.Members
</div>

~/Pages/Shared/DisplayTemplates/Principal.cshtml

public class IndexModel : PageModel
{
    public List<Principal> Principals { get; set; } = new List<Principal>();

    public void OnGet()
    {
        Principals.Add(new Principal { Id = 1, Name = "Principal 1" });
        Principals.Add(new UserPrincipal { Id = 1, Name = "User 1", Age = 30 });
        Principals.Add(new GroupPrincipal { Id = 1, Name = "Group 1", Members = 5 });
        Principals.Add(new UserPrincipal { Id = 1, Name = "User 2", Age = 40 });
        Principals.Add(new GroupPrincipal { Id = 1, Name = "Group 2", Members = 3 });
    }
}

public class Principal
{
    public int Id { get; set; }
    public string Name { get; set; }
}

public class UserPrincipal : Principal
{
    public int Age { get; set; }
}

public class GroupPrincipal : Principal
{
    public int Members { get; set; }
}

@model Principal
<div>
    <h4>Principal</h4>
    @Model.Name
</div>

@model UserPrincipal
<div>
    <h4>User</h4>
    @Model.Name, Age @Model.Age
</div>

@model GroupPrincipal
<div>
    <h4>Group</h4>
    @Model.Name, Members @Model.Members
</div>

@模型主体
校长
@型号.名称

~/Pages/Shared/DisplayTemplates/UserPrincipal.cshtml

public class IndexModel : PageModel
{
    public List<Principal> Principals { get; set; } = new List<Principal>();

    public void OnGet()
    {
        Principals.Add(new Principal { Id = 1, Name = "Principal 1" });
        Principals.Add(new UserPrincipal { Id = 1, Name = "User 1", Age = 30 });
        Principals.Add(new GroupPrincipal { Id = 1, Name = "Group 1", Members = 5 });
        Principals.Add(new UserPrincipal { Id = 1, Name = "User 2", Age = 40 });
        Principals.Add(new GroupPrincipal { Id = 1, Name = "Group 2", Members = 3 });
    }
}

public class Principal
{
    public int Id { get; set; }
    public string Name { get; set; }
}

public class UserPrincipal : Principal
{
    public int Age { get; set; }
}

public class GroupPrincipal : Principal
{
    public int Members { get; set; }
}

@model Principal
<div>
    <h4>Principal</h4>
    @Model.Name
</div>

@model UserPrincipal
<div>
    <h4>User</h4>
    @Model.Name, Age @Model.Age
</div>

@model GroupPrincipal
<div>
    <h4>Group</h4>
    @Model.Name, Members @Model.Members
</div>

@model用户主体
使用者
@Model.Name，Age@Model.Age

~/Pages/Shared/DisplayTemplates/GroupPrincipal.cshtml

public class IndexModel : PageModel
{
    public List<Principal> Principals { get; set; } = new List<Principal>();

    public void OnGet()
    {
        Principals.Add(new Principal { Id = 1, Name = "Principal 1" });
        Principals.Add(new UserPrincipal { Id = 1, Name = "User 1", Age = 30 });
        Principals.Add(new GroupPrincipal { Id = 1, Name = "Group 1", Members = 5 });
        Principals.Add(new UserPrincipal { Id = 1, Name = "User 2", Age = 40 });
        Principals.Add(new GroupPrincipal { Id = 1, Name = "Group 2", Members = 3 });
    }
}

public class Principal
{
    public int Id { get; set; }
    public string Name { get; set; }
}

public class UserPrincipal : Principal
{
    public int Age { get; set; }
}

public class GroupPrincipal : Principal
{
    public int Members { get; set; }
}

@model Principal
<div>
    <h4>Principal</h4>
    @Model.Name
</div>

@model UserPrincipal
<div>
    <h4>User</h4>
    @Model.Name, Age @Model.Age
</div>

@model GroupPrincipal
<div>
    <h4>Group</h4>
    @Model.Name, Members @Model.Members
</div>

@model-GroupPrincipal
团体
@Model.Name，Members@Model.Members

原因主体显示模板用于列表中的所有项目

这是因为

@Html.DisplayFor（expression）

中的表达式根本不会执行。它们是静态解析的
例如，如果我们有一个表达式
m.a.b.c
，其中
a
在运行时是null
，那么
@Html.DisplayFor（m=>m.a.b.c）
仍然能够知道
c
的模板
由于将
主体声明为类型列表，即使创建了模型。主体在运行时持有用户主体或组主体，“解析器”仍然将主体视为基本主体类型：它们不检查实例的真实类型。它们只是静态地分析类型如何修复调用Html.DisplayFor（）时传递模板名称，以便Html助手知道您要使用的真实模板： @page @model IndexModel @foreach (var principal in Model.Principals) { @Html.DisplayFor(p => principal, principal.GetType().Name) } @页面 @模型索引模型 @foreach（Model.Principals中的var主体） { @DisplayFor（p=>principal，principal.GetType（）.Name） } 演示在razor页面中，您是否尝试过@Html.DisplayFor（principal=>principal）？这会生成错误：“名为'principal'的本地或参数不能在此范围内声明，因为该名称在封闭的本地范围内用于定义本地或参数”我过去使用的可能是~/Views/Shared/DisplayTemplates/\u Principle.cshtml 或~/Views/Principals/\u Principle.cshtml 如果您在页面文件夹中使用它，我不确定视图引擎或路由路径是如何配置的，请先在默认路径上尝试，否则您是否在区域内使用它？@sairfan我得到相同的结果，无论是否它们位于“页面”文件夹或“视图”文件夹中。如果将ASP.NET核心Web应用程序项目与.NET核心/框架一起使用，则此操作不起作用。使用ASP.NET Web应用程序（.NET Framework）项目有效。找到此答案，看看这是否有帮助，也可能有帮助