Web Forms :: RenderControl And TreeView?
Mar 16, 2011
I have read many posts in the past about TreeView in Custom CompositeControls and using RenderControl but have yet to see a solution. I declare a new Tree in the CreateChildControls method and in the render I try to call the RenderControls method and it gave me an object reference not set to instance of an object error. I have set the SkipLinkText to Nothing, String.Empty and "". Once I do that I get the second stack trace. The control worked when it was a control on the aspx page.
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STACK TRACE
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Oct 1, 2010
I am trying to find out what html is generated when a control is rendered. For most controls, the following worked fine: Dim tempbuilder As New System.Text.StringBuilder() Dim tempwriter As New
System.Web.UI.HtmlTextWriter(New System.IO.StringWriter(tempbuilder))
Dim generatedhtml as String Me.imgImage.RenderControl(tempwriter) generatedhtml = tempbuilder.ToString()
However, when I tried doing it with an ImageButton, I recieved the following error: Control 'ctl00_cphExampleContent_imgButton' of type 'ImageButton' must be placed inside a form tag with runat=server. What can I do to avoid this?
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Jan 6, 2011
If I have an HtmlTextWriter with some content in it, is it possible to append the output of ontrol.RenderControl to the existing content of the HtmlTextWriter directly?
Or do I always have to output to a separate HtmlTextWriter/StringWriter/StringBuilder and then append the StringBuilder?
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Feb 23, 2010
I need to get the html of a chart control built at runtime. When I call .RenderControl, I get System.NullReferenceException. What could the problem be? Is there another way to go about this (saving as image)? Below is my code.
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Feb 5, 2011
I have today developed a page that builds a series of RadioButtonLists, which may or may not be required fields.
As the page varies depending on DB values, I have rendered the controls using .RenderControl().
Unfortunatley I do not have the code to hand right now, but its along the lines of:
RadioButtonList rblQuestion = new RadioButtonList();
rblQuestion.id = question.ID;
// Add ListItems...
RequiredFieldValidator rfvQuestion = new RequiredFieldValidator();
rfvQuestion.ControlToValidate = rblQuestion.ID;
rfvQuestion.ErrorMessage = "*";
I then use .RenderControl on both rblQuestion and rfvQuestion, concatenate into a string then use the HTML String to populate a PlaceHolder.
This seems to work fine, all appears as expected apart from the RequiredFieldValidator - I get a red asterix (My ErrorMessage) next to each RadioButtonList - But this appears as soon as the page loads, not on a post/button click.
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May 27, 2010
I am using TreeView Control in Asp.net. I have placed this control inside a panel. The tree control is completely binded (we don't want populate on demand) with an Xmldatasource during a callback and then I call Panel.renderControl to return the response (HTML) to the client side callback handler. Problem: 1. The tree expand/collapse (on click of plus sign) is causing postback whereas when I normally bind a tree with xml during postback and without using renderControl of container control, the expand/collapse (on click of plus sign) is being handled at client side. I want to stop this postback and allow tree node to call javascript to toggle nodes as it does when tree is binded and renderd in case of normal page life cycle.(when render control function is not used)
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Jan 18, 2011
I want to do a Jquery POST and get a chart using renderControl attribute of CHart which will return HTML attributes back to browser. The CHart is created dynamically based on parameters passed from post and from model. I have successfully done this on WEbforms,
However the same with MVC give a empty image. The handler doesn't perform the same in MVC2 3.5. I went near to 50 sites now.
I can't use other solution like base64encoding as IE6, 7 don't support it.
What I'm trying to do? I have few data parameteres to be sent (POST) to server and in response get the Chart image as tag along with other attributes and data appended in HTML form and sent to browser, all this to be done using JQUERY. No postbacks to be used.
I have badly searched on google, bing nothing turns out to be valuable.
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Mar 12, 2010
why asp.net does not render a dropdownlist with the autopostback property set to true when using the RenderControl method.
eg
Dim sw As New IO.StringWriter
Dim tw As New HtmlTextWriter(sw)
Dim table As New Table
[Code]...
my output renders the dropdown list without the onchange="javascript:setTimeout('__doPostBack(ddl1','')', 0)" that is generated by asp.net when using the dropdownlist normally.
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Mar 24, 2011
I have a custom web part that I am trying to call the RenderContents method on, but the results only contains the surrounding div for the web part, and not any child controls.
Take for example this simple web part:
namespace MyWebParts
{
public class MyTestWebPart : WebPart
{
public MyTestWebPart()
{
this.CssClass = "myTestWebPart";
}
protected override void CreateChildControls()
{
base.CreateChildControls();
this.Controls.Add(new LiteralControl("Nothing here yet."));
}
}
}
Then, in an http handler, I'm trying to instantiate this web part and call its RenderControl method. The result is <div class="myTestWebPart"></div>.
Does anyone know why I am not getting my controls from CreateChildControls also added to the output?
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Mar 1, 2011
Periodically a rash of occurrences of the following error happen. I believe they're the result of hack attempts. Whether that's the case or not, my question is how can I handle the error? I want to avoid unhandled exceptions. The TreeView control is just
a standard .Net TreeView control, not a custom one. If you suggest a code solution, please code it in VB.Net as that's what I'm using.
Message: Input string was not in a correct format.
Stack Trace:
at System.Number.StringToNumber(String str, NumberStyles options, NumberBuffer& number, NumberFormatInfo info, Boolean parseDecimal)
at System.Number.ParseInt32(String s, NumberStyles style, NumberFormatInfo info)
at System.Web.UI.WebControls.TreeView.LoadPostData(String postDataKey, NameValueCollection postCollection)
at System.Web.UI.WebControls.TreeView.System.Web.UI.IPostBackDataHandler.LoadPostData(String postDataKey, NameValueCollection postCollection)
at System.Web.UI.Page.ProcessPostData(NameValueCollection postData, Boolean fBeforeLoad)
at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
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Nov 15, 2010
I have a treeview which will be generated dynamically which need to be displayed on left side and when user clicks on a node it need to open a page on the right side of the same page. and each node has different aspx page. so whenever user selects a node the page details should be displayed on the right side .we can use an iframe on the page which will display the different pages clicked on the node.Is there any alternative i can use to display different pages based on the user selection on the right side without using iframe.
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May 7, 2015
Code to drag and drop a TreeNode to another control or tag such as Div or even another TreeView.
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Jan 27, 2011
I am using the following code to export a Gridview to an Excel spreadsheet. It works great until I select more than 10 records. At the 11th record I get an error on the line of code that reads....GridView1.RenderControl(hw)The error reads....RegisterForEventValidation can only be called during Render(); Description:An unhandled exception occurred during the execution of the current web request.Please review the stack trace for more information about the error and where it originated in the code.Exception Details: System.InvalidOperationException: RegisterForEventValidation can only be called during Render();Source Error:
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Sub:
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Feb 18, 2010
how to write Css for asp.net treeview by applying color and theme like (msdn website treeview)?
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Oct 1, 2010
I have a treeview that i fill from a database, when i add a new row to a database, the treeview is not updating.Even the reload of an internet explorer doesn't help, It does updates only after i press stop debugging button and turn it on again.Here is the code:
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Jul 12, 2010
I am using treeview to display records from 4-5 SQL Tables. Currently I am using 4-5 different stored procedures to retrieve data based on a dropdownlist value.The tree is loaded everytime the value in the dropdownlist is changed by the user.
Is there a faster way to load treeview as everytime a new selection is made, the treeview is binded again. Or is there any way I can optimize the actions I am performing now to bind the treeview?
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Jul 3, 2010
i would like to add images for a tree view like for root node one image and for child node other like that i would like to add different images for nodes..
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Mar 22, 2010
I am using Tree view to display Categories & SubCategories under it. It's working fine. to create a Tree View I had used,
http://aspalliance.com/732.
Problem is that I want my TreeView to be expanded. How can one do that? Moreover, From another page when I click a Product, I want that in treeView that Category(under which Product falls), should be expanded & node(ie selected Product) should be highlighted.
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Mar 31, 2010
I am using treeview for all of the links that I have created in my Web.sitemap folder. However, I was wondering if there was a way that I could automatically logout after pressing the logout link in the treeview.
I've tried inserting the following code in the logout link within the code behind file :
protected void Page_Load(object sender, EventArgs e)
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Feb 19, 2010
I have a small problem encountered on using Treeview. I have Two pages on the sample. On the first page you can see a button that says "Add Category" and a grid that displays all the previously added categories (coming from a sql db). Upon clicking the "Add Category" button here comes the second page. On that page, we can see a two radio button,a textbox and a submit button. The first radio button says "Add new category", then the second radio says "Add a sub category on the existing category" which shows up the treeview upon clicking. Upon entering the new category and clicking submit, it will return on the First Page and you can see the on the grid the newly added category. Upon adding again and clicking the "add a sub category" the newly added category before was not added even though it was added on the database. Both Grid and the Treeview shares the same SQL statements on retrieving data.
I've tried adding an update panel and even manually updating the Treeview and still the newly item added was not shown. Possible solution I ever found was refreshing the page and I don't want to do that since its kinda ugly. Take note that upon adding a new category and submit it, it will return to the 1st page and upon adding a new category and choosing the sub category radio button showing up the treeview, the newly added category was not shown.
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Apr 8, 2010
I need to display the innertext of the each node as items in my menu along with count (i.e; NewObject1(1), NewObject2(2)). I m using treeview but not able to bind this to treeview using xmldom
Xpath being://Request/NewObject/Object/text(). But not able to read text() attribute to treeview.
<root>
<Request>
<NewObject ID="1"> [code]......
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Apr 13, 2010
How can i remove this gap showing this pic?!!
the gap between name and state?
you can see the gap between Australia and victoria is good, but the gap between Tom and Victoria is too big?
how can i reduce it?
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Apr 5, 2010
we can get a parent & child value by using 'tvCityGroups.SelectedNode.ValuePath' then how can i get the parent & child Text in treeview.
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Jan 13, 2010
i am using treeview in my web application, when i collapse all the node root node becomes disconnect. i mean the root node line is broken. can any one tell me how to fix this issue.
this is my code
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="TreeTest.aspx.cs" Inherits="TreeTest" %>
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Jun 22, 2010
What I am acheiving is a simple treeview which will have a tree structure
dir1
-- xx
dir2
Simple stuff !. Here is the code
TreeNode tree1 = new TreeNode("dir1", "", "", "dir1", "");
tree.Nodes.Add(tree1);
TreeNode node = new TreeNode("xx", "xx");
tree1.ChildNodes.Add(node);
TreeNode tree2 = new TreeNode("dir2", "", "", "dir2", "");
tree.Nodes.Add(tree2);
Now I want to do is collapse all the tree and find a particular node e.g dir1xx
I have put the code
tree.CollapseAll();
tree.FindNode("dir1").Select(); <-- falls over
tree.FindNode("dir1").Expand();
tree.FindNode("dir1/xx").Select();
tree.FindNode("dir1/xx").Expand();
but it falls over on the 2nd line with object not set
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