Custom event from a custom web control is fired twice


S

SammyBar

Hi all,

I created a custom control that fires a custom event, but when it is fired,
the event is received twice...
I have cooked this control from different sources on the Internet an I fear
I'm missing something.
What can be wrong?

It follows a resumed version of the control. It displays a list of files.
This is rendered as a serie of <input type="image">. When the user clicks on
an image an event is sent back to server with the key of the Dictionary
entry selected. This is the event that gets fired twice, I don't know why..

Any hint is welcomed
Thanks in advance
Sammy
public class DownloadsList : WebControl, IPostBackEventHandler

{

// this is the custom argument to the custom event. It only defines a
property: DownloadKey

public class DownloadClickEventArgs : EventArgs

{

private string downloadKey;

public DownloadClickEventArgs() { }

public DownloadClickEventArgs(string aDownloadKey) { downloadKey =
aDownloadKey; }

public string DownloadKey

{

get { return downloadKey; }

set { downloadKey = value; }

}

}

// Here the delegate is defined, then declared

public delegate void DownloadClickEventHandler(object sender,
DownloadClickEventArgs e);

public event DownloadClickEventHandler DownloadClick;

// This is the property through which the data is passed to the control

public Dictionary<string, Download> DownloadsDictionary

{

get

{

return ViewState["DownloadsDictionary"] as Dictionary<string, Download>;

}


set

{

ViewState["DownloadsDictionary"] = value;

}

}

// Now the rendering

protected override void RenderContents(HtmlTextWriter output)

{

foreach (Download download in DownloadsDictionary.Values)

{

ClientScriptManager cs = Page.ClientScript;

output.AddAttribute(HtmlTextWriterAttribute.Onclick,
cs.GetPostBackEventReference(this, download.Key));

output.AddAttribute(HtmlTextWriterAttribute.Type, "image");

output.AddAttribute(HtmlTextWriterAttribute.Src,
ResolveClientUrl(download.DownloadMetadata.IconUrl));

output.RenderBeginTag(HtmlTextWriterTag.Input);

}

}

public void RaisePostBackEvent(string eventArgument)

{

// Putting a breakpoint here it is fired twice

if (this.DownloadClick != null)

this.DownloadClick(this, new DownloadClickEventArgs(eventArgument));

}

}

//-- the Page ----

<form id="form1" runat="server">

<div>

<cc1:DownloadsList ID="DownloadsList1" runat="server"

OnDownloadClick="DownloadsList1_DownloadClick"

/>

</div>

</form>

//--- The Code behind ---

protected void Page_Load(object sender, EventArgs e)

{

// A breakpoint here is hitted twice

if (!IsPostBack)

{

ClientFilesSvc clientFilesSvc = new ClientFilesSvc();

downloads = clientFilesSvc.getDownloads(800455);

DownloadsList1.DownloadsDictionary = downloads;

}

}

protected void DownloadsList1_DownloadClick(object sender,
DownloadsList.DownloadClickEventArgs e)

{

// A breakpoint here is also hitted twice

string key = e.DownloadKey;

Download d = DownloadsList1.DownloadsDictionary[key];

}
 
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E

Erjan Gavalji

Hi Sammy,

An event thrown twice could be caused by the AutoEventWireUp="true"
declaration. You have the event handler already defined in the ASPX code.

Cheers,
Erjan

SammyBar said:
Hi all,

I created a custom control that fires a custom event, but when it is
fired, the event is received twice...
I have cooked this control from different sources on the Internet an I
fear I'm missing something.
What can be wrong?

It follows a resumed version of the control. It displays a list of files.
This is rendered as a serie of <input type="image">. When the user clicks
on an image an event is sent back to server with the key of the Dictionary
entry selected. This is the event that gets fired twice, I don't know
why..

Any hint is welcomed
Thanks in advance
Sammy
public class DownloadsList : WebControl, IPostBackEventHandler

{

// this is the custom argument to the custom event. It only defines a
property: DownloadKey

public class DownloadClickEventArgs : EventArgs

{

private string downloadKey;

public DownloadClickEventArgs() { }

public DownloadClickEventArgs(string aDownloadKey) { downloadKey =
aDownloadKey; }

public string DownloadKey

{

get { return downloadKey; }

set { downloadKey = value; }

}

}

// Here the delegate is defined, then declared

public delegate void DownloadClickEventHandler(object sender,
DownloadClickEventArgs e);

public event DownloadClickEventHandler DownloadClick;

// This is the property through which the data is passed to the control

public Dictionary<string, Download> DownloadsDictionary

{

get

{

return ViewState["DownloadsDictionary"] as Dictionary<string, Download>;

}


set

{

ViewState["DownloadsDictionary"] = value;

}

}

// Now the rendering

protected override void RenderContents(HtmlTextWriter output)

{

foreach (Download download in DownloadsDictionary.Values)

{

ClientScriptManager cs = Page.ClientScript;

output.AddAttribute(HtmlTextWriterAttribute.Onclick,
cs.GetPostBackEventReference(this, download.Key));

output.AddAttribute(HtmlTextWriterAttribute.Type, "image");

output.AddAttribute(HtmlTextWriterAttribute.Src,
ResolveClientUrl(download.DownloadMetadata.IconUrl));

output.RenderBeginTag(HtmlTextWriterTag.Input);

}

}

public void RaisePostBackEvent(string eventArgument)

{

// Putting a breakpoint here it is fired twice

if (this.DownloadClick != null)

this.DownloadClick(this, new DownloadClickEventArgs(eventArgument));

}

}

//-- the Page ----

<form id="form1" runat="server">

<div>

<cc1:DownloadsList ID="DownloadsList1" runat="server"

OnDownloadClick="DownloadsList1_DownloadClick"

/>

</div>

</form>

//--- The Code behind ---

protected void Page_Load(object sender, EventArgs e)

{

// A breakpoint here is hitted twice

if (!IsPostBack)

{

ClientFilesSvc clientFilesSvc = new ClientFilesSvc();

downloads = clientFilesSvc.getDownloads(800455);

DownloadsList1.DownloadsDictionary = downloads;

}

}

protected void DownloadsList1_DownloadClick(object sender,
DownloadsList.DownloadClickEventArgs e)

{

// A breakpoint here is also hitted twice

string key = e.DownloadKey;

Download d = DownloadsList1.DownloadsDictionary[key];

}
 

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