Multiple instances of webpart with custom EditorPart properties

I have recently stumbled upon an interesting problem in a sharepoint webpart.

I wanted to build a webpart that would dynamically create a contact form based on properties that the user set in the webpart property section. Because i wanted to give the user a dropdown from which he would select a sharepoint list from his site, and this dropdown has to populate on load based on his site, i had to use editorpart .

I won`t write about how this is done, because there are many other great posts in other blogs that explain how to do this : link1 , link2 .

After i have implemented the webpart, i have tested it and observed a problem. If i had only one webpart in the site collection, all went according to plan : the user set the properties based upon his needs and the webpart worked well.

The problem appeared when i added another instance of the webpart on another page from that site.  When i set its properties it changed the properties of first webpart as well. This problem persisted in a subsite as well.

After i googled a little i found 2 threads with the same problem, and no answers (in the meantime, i found the solution and answered).

Link1 

Link2

At first i had the properties of the webpart defined like this (this is an example of one):

public static string _emailReceiver;
[WebBrowsable(false), Personalizable(PersonalizationScope.Shared)]
public string EmailReceiver
{

get { return _emailReceiver; }
set { _emailReceiver = value; }
}
In the public class ContactFormWebPartEditorPart : EditorPart i had a textbox defined :
private TextBox Subject;

The apply changes in the editorpart :

public override bool ApplyChanges()
{

EnsureChildControls();

ContactFormWebPart webPart = WebPartToEdit as ContactFormWebPart;

if (webPart != null)

{

webPart.ContactFormList = _dropDownLists.SelectedValue.ToString();

webPart.EmailReceiver = Email.Text;

webPart.EmailSubject = Subject.Text;

webPart.RedirectTo = redirect.Text;

}

return true;

}

All you have to do is to change the EmailReceiver property from the webpart to:

[WebBrowsable(false), Personalizable(PersonalizationScope.Shared)]

public string EmailReceiver

{

get;

set;

}

I have tested it with 3 different webparts, configured each with different properties. It works! Two of them were on the same page!

Maybe it works because the setter and the getter generate random field names on compile time.

Hope that helps!

Sharepoint Impersonation.

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When you create a web form or web part for wss or sharepoint and work with list items for example you should impersonate the current logged user in your application to see who modified, added the list item. I chose this example to be the simplest.
So I created a web part for my sharepoint site.

I added this to the default project created when you choose Sharepoint Web Part project:
c# code:

private string customMessage = "Hello, world!";
[WebBrowsable(true),
WebDescription("Displays a custom message"),
WebDisplayName("Display Message"),
Personalizable(PersonalizationScope.User)]
public string DisplayMessage
{
get { return customMessage; }
set { customMessage = value; }

}

In the render function i added my code. To make a similarity to asp.net you can think of it as page_load handler. Whenever you refresh the page that has the web part on it it executes your code.
Here i get the current logged in user i display it on the screen and then i create a new item in the Announcements List as added by the user logged in:

protected override void Render(System.Web.UI.HtmlTextWriter writer)
{
try
{
HttpContext ctx = HttpContext.Current;
SPWeb web = SPControl.GetContextWeb(this.Context);

if ( (ctx.User != null) && (ctx.User.Identity != null))
customMessage=ctx.User.Identity.Name;
writer.Write(DisplayMessage);

And we show this way the current logged in user.
Now we impersonate the user and create a new item in the Announcements list in his name. Every logged in user has a token (it identifies the authentication process applied to the user).

SPSite impersonatedSiteCollection = new SPSite( SPControl.GetContextSite(this.Context).ID, token);
SPWeb oWebsiteRoot = impersonatedSiteCollection.OpenWeb();
oWebsiteRoot.AllowUnsafeUpdates = true;
SPList oList = oWebsiteRoot.Lists["Announcements"];

SPListItem oListItem = oList.Items.Add();
oListItem["Title"] = "My Item";
oListItem["Created"] = new DateTime(2004, 1, 23);
oListItem["Modified"] = new DateTime(2005, 10, 1);
oListItem.Update();
}
catch (System.ArgumentException e)
{
customMessage = e.Message ;
writer.Write(DisplayMessage);
}

I put it in a try catch sequence because the current logged in user might not have the rights to add a new item to that list and if so the page that contains the webpart will crash and he would not see it even though he has rights to. With the try catch the webpart will tell him that he has no rights.

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