Question

有没有办法让@Html.DisplayFor值显示＆＃34; NULL＆＃34;在视图中，如果模型项的值是null？

这是我目前正在处理的详细信息视图中的项目示例。现在，如果描述的值为null，则不显示任何内容。

<div class="display-field">
    @Html.DisplayFor(model => model.Description)
</div>

Answer 1

是的，我建议在codefirst模型中使用以下数据注释和可空的datetime字段：

[Display(Name = "Last connection")]
[DisplayFormat(NullDisplayText = "Never connected")]
public DateTime? last_connection { get; set; }

然后在你看来：

@Html.DisplayFor(x => x.last_connection)

Answer 2

Display a string e.g. "-" in place of null values show via the "DisplayFor" standard helper using a helper extension, i.e. "DisplayForNull"

1. Create Folder "Helpers" and add a new controller "Helper.cs"

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Linq.Expressions;
using System.Web;
using System.Web.Mvc;

namespace WIPRO.Helpers
{
    public static class Helpers
    {
        public static MvcHtmlString DisplayForNull<TModel, TValue>(this HtmlHelper<TModel> helper, Expression<Func<TModel, TValue>> expression)
        {
            var metaData = ModelMetadata.FromLambdaExpression(expression, helper.ViewData);

        string valuetodisplay = string.Empty;

        if (metaData.Model != null)
        {
            if (metaData.DisplayFormatString != null)
            {
                valuetodisplay = string.Format(metaData.DisplayFormatString, metaData.Model);

            }
            else
            {
                valuetodisplay = metaData.Model.ToString();

            }

        }
        else
        {
            valuetodisplay = "-";

        }

        return MvcHtmlString.Create(valuetodisplay);

    }

}

2. In your view

@using WIPRO.Helpers

@Html.DisplayForNull(model => model.CompanyOwnerPersonName)

in place of

@Html.DisplayFor(model => model.CompanyOwnerPersonName)

Hope it helps ;-)

在ASP.NET MVC DisplayFor Html Helper中为空值显示“NULL”

2 个答案: