asp.net-mvc ASP.NET MVC 3 自定义 HTML 帮助程序 - 最佳实践/使用

ASP.NET MVC 3 Custom HTML Helpers- Best Practices/Uses

提问by stephen776

New to MVC and have been running through the tutorials on the asp.net website.

MVC 新手，并一直在运行 asp.net 网站上的教程。

They include an example of a custom html helper to truncate long text displayed in a table.

它们包括一个自定义 html 帮助程序的示例，用于截断表格中显示的长文本。

Just wondering what other solutions people have come up with using HTML helpers and if there are any best practices or things to avoid when creating/using them.

只是想知道人们使用 HTML 帮助程序提出了哪些其他解决方案，以及在创建/使用它们时是否有任何最佳实践或要避免的事情。

As an example, I was considering writing a custom helper to format dates that I need to display in various places, but am now concerned that there may be a more elegant solution(I.E. DataAnnotations in my models)

例如，我正在考虑编写一个自定义助手来格式化我需要在不同地方显示的日期，但现在担心可能有更优雅的解决方案（我的模型中的 IE DataAnnotations）

Any thoughts?

有什么想法吗？

EDIT:

编辑：

Another potential use I just thought of...String concatenation. A custom helper could take in a userID as input and return a Users full name... The result could be some form of (Title) (First) (Middle) (Last) depending on which of those fields are available. Just a thought, I have not tried anything like this yet.

我刚刚想到的另一个潜在用途...字符串连接。自定义助手可以将用户 ID 作为输入并返回用户全名...结果可能是某种形式的 (Title) (First) (Middle) (Last)，具体取决于哪些字段可用。只是一个想法，我还没有尝试过这样的事情。

采纳答案by Darin Dimitrov

Well in the case of formatting the DisplayFormatattribute could be a nice solution:

那么在格式化DisplayFormat属性的情况下可能是一个不错的解决方案：

[DisplayFormat(DataFormatString = "{0:yyyy-MM-dd}")]
public DateTime Date { get; set; }

and then simply:

然后简单地：

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

As far as truncating string is concerned a custom HTML helper is a good solution.

就截断字符串而言，自定义 HTML 助手是一个很好的解决方案。

---

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UPDATE:

更新：

Concerning your EDIT, a custom HTML helper might work in this situation but there's also an alternative approach which I like very much: view models. So if in this particular view you are always going to show the concatenation of the names then you could define a view model:

关于您的编辑，自定义 HTML 助手可能在这种情况下工作，但还有一种我非常喜欢的替代方法：视图模型。因此，如果在此特定视图中您总是要显示名称的串联，那么您可以定义一个视图模型：

public class PersonViewModel
{
    public string FullName { get; set; }
}

Now the controller is going to query the repository to fetch the model and then map this model to a view model which will be passed to the view so that the view could simply @Html.DisplayFor(x => x.FullName). The mapping between models and view models could be simplified with frameworks like AutoMapper.

现在控制器将查询存储库以获取模型，然后将此模型映射到将传递给视图的视图模型，以便视图可以简单地@Html.DisplayFor(x => x.FullName)。模型和视图模型之间的映射可以通过像AutoMapper这样的框架来简化。

回答by spot

I use HtmlHelpers all the time, most commonly to encapsulate the generation of boilerplate HTML, in case I change my mind. I've had such helpers as:

我一直使用 HtmlHelpers，最常用于封装样板 HTML 的生成，以防我改变主意。我有这样的帮手：

• Html.BodyId(): generates a conventional body id tag for referencing when adding custom css for a view.
• Html.SubmitButton(string): generates either an input[type=submit] or button[type=submit] element, depending on how I want to style the buttons.
• Html.Pager(IPagedList): For generating paging controls from a paged list model.
• etc....

• Html.BodyId()：生成一个常规的body id 标签，用于在为视图添加自定义css 时引用。
• Html.SubmitButton(string)：生成一个 input[type=submit] 或 button[type=submit] 元素，这取决于我想如何设置按钮的样式。
• Html.Pager(IPagedList)：用于从分页列表模型生成分页控件。
• 等等....

One of my favorite uses for HtmlHelpers is to DRY up common form markup. Usually, I have a container div for a form line, one div for the label, and one label for the input, validation messages, hint text, etc. Ultimately, this could end up being a lot of boilerplate html tags. An example of how I have handled this follows:

我最喜欢的 HtmlHelpers 用途之一是删除常见的表单标记。通常，我有一个用于表单行的容器 div，一个用于标签的 div，以及一个用于输入、验证消息、提示文本等的标签。最终，这可能最终成为很多样板 html 标签。我如何处理此问题的示例如下：

public static MvcHtmlString FormLineDropDownListFor<TModel, TProperty>(this HtmlHelper<TModel> helper, Expression<Func<TModel, TProperty>> expression, IEnumerable<SelectListItem> selectList, string labelText = null, string customHelpText = null, object htmlAttributes = null)
{
    return FormLine(
        helper.LabelFor(expression, labelText).ToString() +
        helper.HelpTextFor(expression, customHelpText),
        helper.DropDownListFor(expression, selectList, htmlAttributes).ToString() +
        helper.ValidationMessageFor(expression));
}

public static MvcHtmlString FormLineEditorFor<TModel, TProperty>(this HtmlHelper<TModel> helper, Expression<Func<TModel, TProperty>> expression, string templateName = null, string labelText = null, string customHelpText = null, object htmlAttributes = null)
{
    return FormLine(
        helper.LabelFor(expression, labelText).ToString() +
        helper.HelpTextFor(expression, customHelpText),
        helper.EditorFor(expression, templateName, htmlAttributes).ToString() +
        helper.ValidationMessageFor(expression));
}

private static MvcHtmlString FormLine(string labelContent, string fieldContent, object htmlAttributes = null)
{
    var editorLabel = new TagBuilder("div");
    editorLabel.AddCssClass("editor-label");
    editorLabel.InnerHtml += labelContent;

    var editorField = new TagBuilder("div");
    editorField.AddCssClass("editor-field");
    editorField.InnerHtml += fieldContent;

    var container = new TagBuilder("div");
    if (htmlAttributes != null)
        container.MergeAttributes(new RouteValueDictionary(htmlAttributes));
    container.AddCssClass("form-line");
    container.InnerHtml += editorLabel;
    container.InnerHtml += editorField;

    return MvcHtmlString.Create(container.ToString());
}

public static MvcHtmlString HelpTextFor<TModel, TProperty>(this HtmlHelper<TModel> helper, Expression<Func<TModel, TProperty>> expression, string customText = null)
{
    // Can do all sorts of things here -- eg: reflect over attributes and add hints, etc...
}    

Once you've done this, though, you can output form lines like this:

但是，一旦完成此操作，您就可以像这样输出表单行：

<%: Html.FormLineEditorFor(model => model.Property1) %>
<%: Html.FormLineEditorFor(model => model.Property2) %>
<%: Html.FormLineEditorFor(model => model.Property3) %>

... and BAM, all your labels, inputs, hints, and validation messages are on your page. Again, you can use attributes on your models and reflect over them to get really smart and DRY. And of course this would be a waste of time if you can't standardize on your form design. However, for simple cases, where css can supply all the customization you need, it works grrrrrrrrreat!

...和 ​​BAM，您的所有标签、输入、提示和验证消息都在您的页面上。同样，您可以在模型上使用属性并对其进行反思以获得真正的智能和干燥。当然，如果您不能对表单设计进行标准化，这将是浪费时间。但是，对于简单的情况，css 可以提供您需要的所有自定义项，它的作用是 grrrrrrrrreat！

Moral of the story -- HtmlHelpers can insulate you from global design changes wrecking hand crafted markup in view after view. I like them. But you can go overboard, and sometimes partial views are better than coded helpers. A general rule of thumb I use for deciding between helper vs. partial view: If the chunk of HTML requires a lot of conditional logic or coding trickery, I use a helper (put code where code should be); if not, if I am just outputting common markup without much logic, I use a partial view (put markup where markup should be).

故事的寓意——HtmlHelpers 可以使您免受全局设计更改的影响，这些更改会破坏手工制作的标记。我喜欢他们。但是你可以做得过火，有时部分视图比编码助手更好。我用来决定辅助视图和部分视图的一般经验法则：如果 HTML 块需要大量条件逻辑或编码技巧，我使用辅助工具（将代码放在应该放置的地方）；如果没有，如果我只是在没有太多逻辑的情况下输出通用标记，我会使用局部视图（将标记放在标记应该所在的位置）。

Hope this gives you some ideas!

希望这能给你一些想法！

回答by satya prakash

public static HtmlString OwnControlName<T, U>(this HtmlHelper<T> helper, Expression<Func<T, U>> expression, string label_Name = "", string label_Title = "", Attr attr = null)
        {
            TemplateBuilder tb = null;
            string template = null;
          if (expression == null) throw new ArgumentException("expression");
 obj = helper.ViewData.Model;
                tb.Build(obj, expression.Body as MemberExpression, typeof(T), new SimpleTemplate(new TextArea()), label_Name, label_Title, attr);
                template = tb.Get();
 return new MvcHtmlString(template);
}