使用泛型和LINQ MVC3 HtmlHelpers

更新

我正在尝试创建一个HtmlHelper扩展程序,该扩展程序具有接受TModels集合的功能.然后设置一个表达式,该表达式将获取集合中每个项目的声明属性并打印出来.

下面的代码可以正常工作.但是,我目前不喜欢的模式中有一件事是无法推断出泛型类型.我必须为扩展方法声明类型.

我正在尝试遵循Telerik用于其Grid的模式类型,在该模式下,当您声明模型时,便会推断出通用类型.

我想这样做：

@model List<MyProject.MyModels.UserModel>
@(Html.MyExtensions()
      .PrintUsers(Model)
      .FirstName(m => m.FirstName)
      .LastName(m => m.LastName)
)

按照我目前的模式,我必须这样做：

@model List<MyProject.MyModels.UserModel>
@(Html.MyExtensions<List<MyProject.MyModels.UserModel>, MyProject.MyModels.UserModel>()
      .PrintUsers(Model)
      .FirstName(m => m.FirstName)
      .LastName(m => m.LastName)
)

因此,我需要找出一个更好的模式,以便推断出我的类型.
有任何想法吗？

UserModel看起来像：

public class UserModel
{
    public string FirstName { get; set; }
    public string LastName { get; set; }
}

所以我有一个HtmlHelper看起来像这样：

public static class UIExtension
{
    public static ComponentFactory<TModel, T> MyExtensions<TModel, T>(this HtmlHelper<TModel> html) 
        where TModel : IEnumerable<T>
        where T : class
    {
        return new ComponentFactory<TModel, T>(html);
    }
}

因此,我的组件之一将获取一个List,然后遍历通过Linq Expression将每个声明的属性打印到页面.

在我的ComponentFactory中,我有：

public class ComponentFactory<TModel, T>
    where T : class
{
    private HtmlHelper<TModel> _html;

    public ComponentFactory()
    {
    }

    public ComponentFactory(HtmlHelper<TModel> html)
    {
        this._html = html;
    }

    public ListComponent<T> PrintUsers(IEnumerable<T> model)
    {
        return new ListComponent<T>(model);
    }

    /* Add other ui components to this factory */
}

然后我的ListComponent

public class ListComponent<T> : IHtmlString
{
    private Expression<Func<T, string>> _firstname;
    private Expression<Func<T, string>> _lastname;

    private IEnumerable<T> _model;

    public ListComponent(IEnumerable<T> model)
    {
        this._model = model;
    }

    public ListComponent<T> FirstName(Expression<Func<T, string>> property)
    {
        this._firstname = property;
        return this;
    }

    public ListComponent<T> LastName(Expression<Func<T, string>> property)
    {
        this._lastname = property;
        return this;
    }

    public override MvcHtmlString Render()
    {
        TagBuilder container = new TagBuilder("div");

        TagBuilder title = new TagBuilder("div");
        title.InnerHtml = "<b>Names</b>";
        container.InnerHtml = title.ToString(TagRenderMode.Normal);

        TagBuilder ul = new TagBuilder("ul");

        foreach (var item in this._model)
        {
            TagBuilder li = new TagBuilder("li");
            li.SetInnerText(String.Format("{0} {1}", _firstname.Compile()(item), _lastname.Compile()(item)));
            ul.InnerHtml += li.ToString(TagRenderMode.Normal);
        }

        container.InnerHtml += ul.ToString(TagRenderMode.Normal);

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

感谢您的帮助和建议！

解决方法:

像这样的事情呢：

public static class UIExtension
{
    public static ComponentFactory<TModel> MyExtensions<TModel>(this HtmlHelper<IEnumerable<TModel>> html) where TModel : class

    {
        return new ComponentFactory<TModel>(html);
    }
}
public class UserModel
{
    public string FirstName { get; set; }
    public string LastName { get; set; }
}
public class ComponentFactory<TModel>
where TModel : class
{
    private HtmlHelper _html;

    public ComponentFactory()
    {
    }

    public ComponentFactory(HtmlHelper<IEnumerable<TModel>> html)
    {
        this._html = html;
    }

    public ListComponent<TModel> PrintUsers(IEnumerable<TModel> model)
    {
        return new ListComponent<TModel>(model);
    }

    /* Add other ui components to this factory */
}
public class ListComponent<T> : IHtmlString
{
    private Expression<Func<T, string>> _firstname;
    private Expression<Func<T, string>> _lastname;

    private IEnumerable<T> _model;

    public ListComponent(IEnumerable<T> model)
    {
        this._model = model;
    }

    public ListComponent<T> FirstName(Expression<Func<T, string>> property)
    {
        this._firstname = property;
        return this;
    }

    public ListComponent<T> LastName(Expression<Func<T, string>> property)
    {
        this._lastname = property;
        return this;
    }



public override MvcHtmlString Render()
{
    TagBuilder container = new TagBuilder("div");

    TagBuilder title = new TagBuilder("div");
    title.InnerHtml = "<b>Names</b>";
    container.InnerHtml = title.ToString(TagRenderMode.Normal);

    TagBuilder ul = new TagBuilder("ul");

    foreach (var item in this._model)
    {
        TagBuilder li = new TagBuilder("li");
        li.SetInnerText(String.Format("{0} {1}", _firstname.Compile()(item), _lastname.Compile()(item)));
        ul.InnerHtml += li.ToString(TagRenderMode.Normal);
    }

    container.InnerHtml += ul.ToString(TagRenderMode.Normal);

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

用法如下：

Html.MyExtensions().PrintUsers(Model).FirstName(p=>p.FirstName).LastName(p=>p.LastName)

标签：html-helper,linq,c,asp-net-mvc-3
来源： https://codeday.me/bug/20191208/2089881.html