有没有办法创建一个Tag Helper,以某种方式迭代(像转发器一样)内部标记助手？就是这样的：
<big-ul iterateover='x'> <little-li value='uses x somehow'></little-li> </bg-ul>
我知道我可以用razor foreach做到这一点但是试图找出如何做而不必在我的html中切换到c#代码.
解决方法
通过使用TagHelperContext.Items属性,这是可能的.从
doc：
Gets the collection of items used to communicate with other
ITagHelpers. ThisSystem.Collections.Generic.IDictionary<TKey,TValue>is copy-on-write in order to ensure items added to this collection are visible only to otherITagHelperstargeting child elements.
这意味着您可以将父标记助手中的对象传递给其子对象.
例如,假设您要迭代Employee列表：
public class Employee
{
public string Name { get; set; }
public string LastName { get; set; }
}
在您的视图中,您将使用(例如)：
@{
var mylist = new[]
{
new Employee { Name = "Alexander",LastName = "Grams" },new Employee { Name = "Sarah",LastName = "Connor" }
};
}
<big-ul iterateover="@mylist">
<little-li></little-li>
</big-ul>
和两个标签助手：
[HtmlTargetElement("big-ul",Attributes = IterateOverAttr)]
public class BigULTagHelper : TagHelper
{
private const string IterateOverAttr = "iterateover";
[HtmlAttributeName(IterateOverAttr)]
public IEnumerable<object> IterateOver { get; set; }
public override async Task ProcessAsync(TagHelperContext context,TagHelperOutput output)
{
output.TagName = "ul";
output.TagMode = TagMode.StartTagAndEndTag;
foreach(var item in IterateOver)
{
// this is the key line: we pass the list item to the child tag helper
context.Items["item"] = item;
output.Content.AppendHtml(await output.GetChildContentAsync(false));
}
}
}
[HtmlTargetElement("little-li")]
public class LittleLiTagHelper : TagHelper
{
public override void Process(TagHelperContext context,TagHelperOutput output)
{
// retrieve the item from the parent tag helper
var item = context.Items["item"] as Employee;
output.TagName = "li";
output.TagMode = TagMode.StartTagAndEndTag;
output.Content.AppendHtml($"<span>{item.Name}</span><span>{item.LastName}</span>");
}
}
