将对象传递给动态加载的ListView ItemTemplate [英] Pass object to dynamically loaded ListView ItemTemplate

问题描述

我一直在关注以下有关在ListView控件中使用多个ItemTemplates的帖子.

I have been following the following post on using multiple ItemTemplates in a ListView control.

尽管在此示例中确实产生了输出，但我正在尝试找出如何将一个对象通过psas传递到ItemTemplate的用户控件，而我似乎无法执行/设计该对象.

While following this example does produce output, I am trying ot figure out how to psas an object through to the ItemTemplate's user control, which I do not seem to be able to do/figure out.

protected void lvwComments_OnItemCreated(object sender, ListViewItemEventArgs e)
    {
        ListViewDataItem currentItem = (e.Item as ListViewDataItem);
        Comment comment = (Comment)currentItem.DataItem;

        if (comment == null)
            return;

        string controlPath = string.Empty;

        switch (comment.Type)
        {
            case CommentType.User:
                controlPath = "~/layouts/controls/General Comment.ascx";
                break;
            case CommentType.Official:
                controlPath = "~/layouts/controls/Official Comment.ascx";
                break;
        }
        lvwComments.ItemTemplate = LoadTemplate(Controlpath);
    }

用户控件如下:

public partial class OfficialComment : UserControl
{
    protected void Page_Load(object sender, EventArgs e)
    {

    }
}

在此示例中，值正在ascx页中输出:

In the example, the values are being output in the ascx page:

<%# Eval("ItemName") %>

但是我需要访问此控件中的ListItem来执行其他逻辑.我无法弄清楚如何通过我的评论项目发送.发件人对象和EventArgs不包含该信息.

however I need to access the ListItem in this control to do other logic. I cannot figure out how I to send through my Comment item. The sender object and EventArgs do not contain the info.

理想情况下，我想获得有关使用<％#Eval％>语句时控件如何访问数据项的说明.我能够确定的是以下几种方式访问​​当前项目的方法:

Ideally, I would like to obtain an explanation as to how the control accesses the dataitem when using the <%# Eval %> statement. What I have been able to determine, is the following way to gain access to the current item:

我创建了一个自定义ListView控件，该控件在ItemCreating上设置了dataItemIndex.

I have created a custom ListView control, which set's the dataItemIndex on ItemCreating.

在我的官方评论控件中，添加以下内容:

In my Official comment control, I add the following:

List<Comment> commentList = ((CommentListView)this.Parent.Parent.Parent).DataSource as List<Comment>;

if (commentList != null)
{
    int currentIndex = ((ListViewDataItem)this.Parent).DataItemIndex;
    Comment currentItem = commentList[currentIndex];
}

推荐答案

虽然有关于动态项目模板的文档，但是除了<％#Eval％>函数之外，没有其他示例可以访问数据.在尝试了一些问题后，我不喜欢必须递归遍历控制树.

While there is documentation on dynamic Item Templates, no examples progressed through to accessing data other that the <%# Eval %> function. After trying some methods, shown in my question, I was not a fan of having to recursively traverse up the control tree.

我能够做的是创建一个从UserControl继承的类.此类将定义我的DataItem:

What I've been able to do is create a class that inherits from UserControl. This class will define my DataItem:

public partial class ListViewTemplateControl<T> : UserControl where T : class
{
    public T CurrentItem { get; set; }
}

然后，在我的ListView中，我可以执行以下操作:

Then, in my ListView, I can perform the following:

    protected void lvwComments_OnItemCreated(object sender, ListViewItemEventArgs e)
    {
        ListViewDataItem currentItem = (e.Item as ListViewDataItem);
        Comment comment = (Comment)currentItem.DataItem;

        if (comment == null)
            return;

        string controlPath = string.Empty;

        switch (comment.Type)
        {
            case CommentType.User:
                controlPath = "~/layouts/controls/General Comment.ascx";
                break;
            case CommentType.Official:
                controlPath = "~/layouts/controls/Official Comment.ascx";
                break;
        }

        ListViewTemplateControl<Comment> templateControl = LoadControl(controlPath) as ListViewTemplateControl<Comment>;

        if (templateControl != null)
        {
            templateControl.CurrentItem = comment;
            templateControl.ID = comment.ItemID;
            lvwComments.Controls.Add(templateControl);
        }
    }

现在，在模板控件中，我可以基于传递的CurrentItem(DataItem)执行所有自定义逻辑.唯一需要注意的是<％#Eval％>函数现在将无法使用.

In my template control, I can now perform all my custom logic based on the CurrentItem (DataItem) that I pass through. The only caveat to this is that <%# Eval %> function will not work now.

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