错误

我收到了错误：

((ContentPlaceHolder)Page.Master.FindControl("JavascriptIncludes")).Controls.Add(JSIncludes);
System.ArgumentNullException: Value cannot be null.

这是我的网络用户控制。这里的空值是我试图添加的JSIncludes控件。它存在于Web用户控件中！如果我把它分解为：

Literal NewLit = new Literal();
NewLit.Text = "TESTING";
JSIncludes.Controls.Add(NewLit);

我明白了：

System.NullReferenceException: Object reference not set to an instance of an object.
JSIncludes.Controls.Add(NewLit);

它位于我的web.config控件下：

<add tagPrefix="Scirra" src="~/Controls/Article/ArticleSubmitForm.ascx" tagName="ArticleSubmitForm"/>

母版页

    snip
    <script src="<%=ResolveClientUrl("~/js/scrollTo-min.js")%>"></script> 
    <asp:ContentPlaceHolder id="JavascriptIncludes" runat="server"></asp:ContentPlaceHolder>
</form>    

</body>

</html>

内容页面

我的教程页面：

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Tutorials.aspx.cs" Inherits="Tutorials" MasterPageFile="MasterPages/Main.master" %>
<%@ MasterType VirtualPath="~/MasterPages/Main.master" %>
<%@ Reference Control="~/Controls/Article/ArticleSubmitForm.ascx" %>

<asp:Content ID="Content1" ContentPlaceHolderID="MainContent" Runat="Server">


<asp:Placeholder runat="server" ID="DefaultView" Visible="false">

    <div class="center">
        <h1>Tutorials</h1><br />
    </div>

</asp:Placeholder>
<asp:Placeholder runat="server" ID="SubmitView" Visible="false">

    <div class="center">
        <h1>Submit a Tutorial</h1><br />
    </div>

    <asp:PlaceHolder runat="server" ID="ArticleSubbmitter" />    

</asp:Placeholder>

</asp:Content>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class Tutorials : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        string Section = Request.QueryString["section"];

        if (Section == "submit")
        {
            // Menu selection
            Master.SetTopMenuSelected("tut");
            Master.SetSubMenuSelected("submit");

            // Page meta data
            Page.Title = Meta.TUTORIAL_SUBMIT_TITLE + Meta.TITLE_SUFFIX; ;
            Master.AddMetaDescription(Meta.TUTOTIAL_SUBMIT_DESCRIPTION);

            // Canonicial meta link
            string ThisPageURL = Settings.MasterDomainRoot + "/tutorials/submit";
            Master.AddCanonical(ThisPageURL);
            SubmitView.Visible = true;

            // Forced tags for input
            Controls_ArticleSubmitForm SubmitForm = new Controls_ArticleSubmitForm();
            SubmitForm.ForcedTags = new string[] { "Tutorials" };
            SubmitForm.Section = "Tutorials";
            SubmitForm.ThisUser = Master.ThisUser;
            ArticleSubbmitter.Controls.Add(SubmitForm);            
        }
        else
        {
            // Menu selection
            Master.SetTopMenuSelected("tut");
            Master.SetSubMenuSelected("home");

            // Page meta data
            Page.Title = Meta.TUTORIAL_TITLE + Meta.TITLE_SUFFIX; ;
            Master.AddMetaDescription(Meta.TUTORIAL_DESCRIPTION);

            // Canonicial meta link
            string ThisPageURL = Settings.MasterDomainRoot + "/tutorials";
            Master.AddCanonical(ThisPageURL);

            DefaultView.Visible = true;
        }


    }
}

我的控制

控制本身：

<%@ Control Language="C#" AutoEventWireup="true" CodeFile="ArticleSubmitForm.ascx.cs" Inherits="Controls_ArticleSubmitForm" %>


<div class="article-edit-wrapper">
<h3>Title</h3>
<asp:TextBox runat="server" ID="ArticleTitle" CssClass="nice-textbox wide" MaxLength="65" /><br /><br />

<h3>Body</h3>
<asp:TextBox runat="server" ID="ArticleInput" CssClass="article-edit-area" TextMode="MultiLine" />

<div id="DraftNotice" style="float:left"></div>
<div style="float:right">Auto Preview <input type="checkbox" checked="checked" id="AutoPreview" onchange="UpdatePV(this)" /></div>
<div class="clear"></div><br />

<h3>Preview</h3>
<div id="PreviewArea" class="article-preview"></div>

<br />
<h3>Tags</h3>
<Scirra:TagEntry runat="server" ID="TagInput" />

<br /><asp:Button runat="server" ID="SubmitButton" CssClass="nice-button" Text="Submit" />

</div>

<asp:PlaceHolder runat="server" ID="CSSIncludes">
    <link rel="stylesheet" href="<%=ResolveClientUrl("~/css/article.css")%>" /> 
</asp:PlaceHolder>
<asp:PlaceHolder runat="server" ID="JSIncludes">

    <script src="<%=ResolveClientUrl("~/js/FieldSelect.js")%>"></script> 
    <script src="<%=ResolveClientUrl("~/js/KBShortcuts.js")%>"></script> 
    <script src="<%=ResolveClientUrl("~/js/ArticleCommon.js")%>"></script> 
    <script>
        var ArticleAJAXURL = "<%=ResolveClientUrl("~/Handlers/ArticlesAjaxHandler.ashx")%>";
        var Section = "<%=Section%>";
    </script>
    <script>
        // Called when edit area is modified
        function UpdatePreview() {

            if (AutoPreview) {

                // Get relevent items
                var PreviewArea = $('#PreviewArea');
                var InputTxt = $('textarea#ArticleInput').val();

                // Update preview
                PreviewArea.html(FormatInput(InputTxt));

            }
        }

        var R = 1;
        shortcut.add("Ctrl+H", function () {
            PerformShortcut("[", "][" + (R++) + "]", "Enter link description");
        });

        // Function called to save draft
        var LastSavedTitle = "";
        var LastSavedBody = "";
        function SaveDraft() {

            var Body = $.trim($('textarea#ArticleInput').val());
            var Title = $.trim($('#ArticleTitle').val());

            if ((Body.length > 0 || Title.length > 0) && (LastSavedTitle != Title || LastSavedBody != Body)) {

                // Build data
                var DataString =    "&section=" + Section +
                                    "&body=" + Body +
                                    "&title=" + Title;
                LastSavedTitle = Title;
                LastSavedBody = Body;

                // Post it
                $.ajax({
                    type: 'POST',
                    url: ArticleAJAXURL + "?action=savedraft",
                    data: DataString,
                    success: (function (data) {

                        var SplitD = data.split("|");
                        $('#DraftNotice').html(SplitD[1]);
                        $('#DraftNotice').fadeOut('slow', function () {});

                    })
                });  
            }
        }
        setInterval(SaveDraft, 2000);

        // Formats input into HTML
        function FormatInput(Text) {

            // Newlines to breaks
            Text = Text.replace(new RegExp("\n", "g"), '<br />')

            // **bold**
            Text = Text.replace(new RegExp("\\*\\*(.+?)\\*\\*", "g"), '<strong>$1</strong>');

            // *italic*
            Text = Text.replace(new RegExp("\\*(.+?)\\*", "g"), '<em>$1</em>');

            // ##header 1##
            Text = Text.replace(new RegExp("##(.+?)##", "g"), '<h2>$1</h2>');

            // #header 2##
            Text = Text.replace(new RegExp("#(.+?)#", "g"), '<h3>$1</h3>');

            // Relpace trailing breaks after header close tags
            Text = Text.replace(new RegExp("</h2>(\<br \/\>)*", "g"), "</h2><br />");
            Text = Text.replace(new RegExp("</h3>(\<br \/\>)*", "g"), "</h2><br />");

            // Youtube
            Text = Text.replace(new RegExp("\\[tube:(.+?)\\]", "gi"), "<object type=\"application/x-shockwave-flash\" class=\"youtube-embed\" data=\"http://www.youtube.com/v/$1\"><param name=\"movie\" value=\"http://www.youtube.com/v/$1\" /></object>");
            Text = Text.replace(new RegExp("</object>(\<br \/\>)*", "g"), "</object><br /><br />");

            // Insert title
            var Title = $.trim($('#ArticleTitle').val());
            if(Title.length > 0)
                Text = "<h1>" + Title + "</h1><br />" + Text;

            return Text;
        }
    </script>

</asp:PlaceHolder>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class Controls_ArticleSubmitForm : System.Web.UI.UserControl
{
    public string[] ForcedTags { get; set; }
    public string Section { get; set; }
    public LoggedInUser ThisUser { get; set; }

    protected void Page_Load(object sender, EventArgs e)
    {
        // Include the CSS/JS

        ((ContentPlaceHolder)Page.Master.FindControl("JavascriptIncludes")).Controls.Add(JSIncludes);
        ((ContentPlaceHolder)Page.Master.FindControl("HeadContent")).Controls.Add(CSSIncludes);

        // Initialise the edit area
        ArticleInput.Attributes.Add("onkeyup", "UpdatePreview()");
        ArticleInput.Attributes.Add("onchange", "UpdatePreview()");
        ArticleTitle.Attributes.Add("onkeyup", "UpdatePreview()");
        ArticleTitle.Attributes.Add("onchange", "UpdatePreview()");

        // Get forced tags
        TagInput.DefaultTagList = this.ForcedTags;

        // Load draft if one exists
        using (DataClassesDataContext db = new DataClassesDataContext())
        {
            var q = (from d in db.tblDrafts where d.Section == this.Section && d.UserID == ThisUser.UserID select new { d.Title, d.Draft }).SingleOrDefault();
            if (q != null)
            {
                ArticleTitle.Text = q.Title;
                ArticleInput.Text = q.Draft;
            }
        }
    }
}

Answer 1

这让我感到不安，最后修好了。

Controls_ArticleSubmitForm SubmitForm =       LoadControl("~/Controls/Article/ArticleSubmitForm.ascx") as Controls_ArticleSubmitForm;

您无法以编程方式执行新的MyControl（）。

无法添加到null构建错误

错误

母版页

内容页面

我的控制

1 个答案: