Wrapping Standard Controls for Use in Web Parts

Web Part controls can be a good solution, especially when you are creating a control from scratch. However, you might often have an existing control that would make a great Web Part. What problems might you face when using your existing user controls or custom controls?

Looking back at the examples in Chapter 4, notice that all of the native controls not derived from the WebPart class dropped into a WebPartZone control have "Untitled" as their title; of course, customizing the icon is not possible. The same is also true of adding user controls as Web Parts.

So, do you have to give up custom titles or icons to get the advantages of user controls? Thankfully, the answer is no. Recall the code used in Chapter 4 to programmatically add a TextBox control as a Web Part.

GenericWebPart gwp = this.WebPartManager1.CreateWebPart(tb); this.WebPartManager1.AddWebPart(gwp, this.WebPartZone1, 0);

The GenericWebPart class acts as a wrapper for the class when you create a Web Part. If you wanted to, you could set properties of the GenericWebPart control in the Page_Init event handler of the user control, as shown here.

void Page_Init(object sender,EventArgs e) {     GenericWebPart gwp = Parent as GenericWebPart;     if ( gwp != null )     {         gwp.Title="New User Control/Web Part Title";     } }

Another alternative is to implement the IWebPart interface in a user control. The IWebPart interface consists of several properties. These properties are the values that you would probably want to change, such as Title and TitleIconImageUrl.

To demonstrate how implementing the IWebPart interface works in a user control, I created a copy of DisplayBlogEntryUC.aspx, naming it DisplayBlogEntryUCasWP.ascx. In the class declaration, I added the IWebPart interface after UserControl in the class declaration, to indicate that the class implements the IWebPart interface, as shown here.

#region IWebPart Members private string catalogIconImageUrl; private string description; private string subTitle; private string title; private string titleIconImageUrl; private string titleUrl; public string CatalogIconImageUrl { get { return catalogIconImageUrl; } set { catalogIconImageUrl=value; } } public string Description { get { return description; } set { description=value; } } public string Subtitle { get { return subTitle; } } public string Title { get { return title; } set { title=value; } } public string TitleIconImageUrl { get { return titleIconImageUrl; } set { titleIconImageUrl = value; } } public string TitleUrl { get { return titleUrl; } set { titleUrl=value; } } #endregion

public DisplayBlogEntryUCasWP() { catalogIconImageUrl=string.Empty; description = string.Empty; subTitle = string.Empty; title = "Bike Blog"; titleIconImageUrl = string.Empty; titleUrl = string.Empty; } protected void Page_Load(object sender, EventArgs e) { // Should really get most recent entry... this.BlogEntryID = 7; }

protected void Page_Load(object sender, EventArgs e) { if (this.WebPartManager1.WebParts.Count == 0) { Control uc = this.LoadControl("~/DisplayBlogEntryUCasWP.ascx"); uc.ID = "UCasWP1"; GenericWebPart gwp = WebPartManager1.CreateWebPart(uc); this.WebPartManager1.AddWebPart(gwp, this.WebPartZone1, 0); } }