获取页面上特定类型的所有Web控件

查看我之前的SO答案

基本上，这个想法是使用 来包装遍历控件集合的递归:

private void GetControlList<T>(ControlCollection controlCollection, List<T> resultCollection)
where T : Control
{
    foreach (Control control in controlCollection)
    {
        //if (control.GetType() == typeof(T))
        if (control is T) // This is cleaner
            resultCollection.Add((T)control);
        if (control.HasControls())
            GetControlList(control.Controls, resultCollection);
    }
}

和使用它:

List<DropDownList> allControls = new List<DropDownList>();
GetControlList<DropDownList>(Page.Controls, allControls )
foreach (var childControl in allControls )
{
//     call for all controls of the page
}

[编辑:11/26/2013]:这里有一个更优雅的方法来达到这个目标。我编写了两个扩展方法，它们可以在两个方向上遍历控制树。这些方法以更Linq的方式编写，因为它产生一个可枚举的:

/// <summary>
/// Provide utilities methods related to <see cref="Control"/> objects
/// </summary>
public static class ControlUtilities
{
    /// <summary>
    /// Find the first ancestor of the selected control in the control tree
    /// </summary>
    /// <typeparam name="TControl">Type of the ancestor to look for</typeparam>
    /// <param name="control">The control to look for its ancestors</param>
    /// <returns>The first ancestor of the specified type, or null if no ancestor is found.</returns>
    public static TControl FindAncestor<TControl>(this Control control) where TControl : Control
    {
        if (control == null) throw new ArgumentNullException("control");
        Control parent = control;
        do
        {
            parent = parent.Parent;
            var candidate = parent as TControl;
            if (candidate != null)
            {
                return candidate;
            }
        } while (parent != null);
        return null;
    }
    /// <summary>
    /// Finds all descendants of a certain type of the specified control.
    /// </summary>
    /// <typeparam name="TControl">The type of descendant controls to look for.</typeparam>
    /// <param name="parent">The parent control where to look into.</param>
    /// <returns>All corresponding descendants</returns>
    public static IEnumerable<TControl> FindDescendants<TControl>(this Control parent) where TControl : Control
    {
        if (parent == null) throw new ArgumentNullException("control");
        if (parent.HasControls())
        {
            foreach (Control childControl in parent.Controls)
            {
                var candidate = childControl as TControl;
                if (candidate != null) yield return candidate;
                foreach (var nextLevel in FindDescendants<TControl>(childControl))
                {
                    yield return nextLevel;
                }
            }
        }
    }
}

由于this关键字，这些方法都是扩展方法，可以简化代码。

例如，要查找页面中的所有DropDownList，您可以简单地调用:

var allDropDowns = this.Page.FindControl<DropDownList>();

由于使用了yield关键字，并且因为Linq足够智能来延迟枚举的执行，您可以调用(例如):

var allDropDowns = this.Page.FindDescendants<DropDownList>();
var firstDropDownWithCustomClass = allDropDowns.First(
    ddl=>ddl.CssClass == "customclass"
    );

只要满足First方法中的谓词，枚举就会停止。不会遍历整个控制树

foreach (DropDownList dr in this.Page.Form.Controls.OfType<DropDownList>())
{
}

这里是一个递归版本，它返回所请求类型的控件集合，而不是使用另一个参数:

using System.Collections.Generic;
using System.Web.UI;
// ...
public static List<T> GetControls<T>(ControlCollection Controls)
where T : Control {
  List<T> results = new List<T>();
  foreach (Control c in Controls) {
    if (c is T) results.Add((T)c);
    if (c.HasControls()) results.AddRange(GetControls<T>(c.Controls));
  }
  return results;
}

插入到类中(静态可选)

有这个问题，虽然我发现Steve B的答案很有用，但我想要一个扩展方法，所以重构了它:

    public static IEnumerable<T> GetControlList<T>(this ControlCollection controlCollection) where T : Control
    {
        foreach (Control control in controlCollection)
        {
            if (control is T)
            {
                yield return (T)control;
            }
            if (control.HasControls())
            {
                foreach (T childControl in control.Controls.GetControlList<T>())
                {
                    yield return childControl;
                }
            }
        }
    }

在一个页面上循环遍历控件并不难——你只需要在每个控件中寻找更多的控件。

你可以这样写

foreach(var control in Page)
{
    if(control is DropDownList)
    {
        //Do whatever
    }
    else
    {
        //Call this function again to search for controls within this control
    }
}

您可以使用递归逻辑获取所有控件，如下所示:

private void PopulateSelectList(Control parentCtrl, List<DropDownList> selectList)
{
    foreach (Control ctrl in parentCtrl.Controls)
    {
        if (ctrl is DropDownList)
        {
            selectList.Add(((DropDownList)ctrl);
            continue;
        }
        FindAllControls(ctrl, selectList);
    }
}

        var dropDownLists = new List<DropDownList>();
        foreach (var control in this.Controls)
        {
            if (control is DropDownList)
            {
                dropDownLists.Add( (DropDownList)control );
            }
        }

如果您使用system.web.ui中的表单组件，则此操作有效然而，当你从system.web.mvc中使用它们时，这显然不起作用，所以我提出了以下工作。

for (Int32 idx = 0; idx < formCollection.Count; idx += 1)
                    {
                    String Name = formCollection.Keys[idx];
                    String value = formCollection[idx];
                    if (Name.Substring(0, 3).ToLower() == "chk")
                        {
                        Response.Write(Name + " is a checkbox <br/>");
                        }
                    else if (Name.Substring(0, 5).ToLower() == "txtar")
                        {
                        Response.Write(Name + " is a text area <br/>");
                        }
                    else if (Name.Substring(0, 2).ToLower() == "rd")
                        {
                        Response.Write(Name + " is a RadioButton <br/>");
                        }
                    }

这对我来说是有效的，但是我发现，单选按钮，如果没有选择是空的，所以不返回任何东西，这是ok的，我不需要写任何东西到数据库，如果它是空