Discussing the ins and outs of developing for SharePoint and the Microsoft platform

This has been something that bugs me about most page layouts I have done before – you have a field like the description or something like that and when you put it in you have to put it in a <p> tag to get it to render properly. The problem then is that if you don’t populate the field you then don’t want the <p> tag outside the element to render otherwise you will have some unwanted white space. I had a quick Google around and found a pretty good solution for this here.

Essentially the solution involves creating a custom control based on the security trimmer control, and telling it to trim the components inside it when the specific field is blank. I found the code example at that URL didn’t quite work, so here is my code with some minor adjustments made:

public class HideWhenBlank : SPSecurityTrimmedControl
{
    public String FieldNameToCheck { get; set; }   

    protected override void Render(System.Web.UI.HtmlTextWriter output)
    {
        SPListItem item = null;
        WebPartDisplayMode mode = ((SPWebPartManager)this.Page.Master.FindControl("wpmMain")).DisplayMode;   if (mode.Name == "Design")
        {
            base.Render(output);
        }
        else if (SPContext.Current != null)
        {
            item = SPContext.Current.ListItem;
            if (!String.IsNullOrEmpty(FieldNameToCheck) && item != null)
            {
                if (!ValueIsNullOrBlank(item[FieldNameToCheck]))
                {
                    base.Render(output);
                }
            }
        }
    }

    private Boolean ValueIsNullOrBlank(Object data)
    {
        if (data == null || String.IsNullOrEmpty(Convert.ToString(data).Trim()))
        {
            return true;
        }
        else
        {
            return false;
        }
    }
}

Compile this class and you can go and use this one in your page layouts like this:

<MyCustomTagPrefix:HideWhenBlank runat="server" FieldNameToCheck="Comments">
<p>
<!-- Some sort of custom publishing element in here -->
</p>
</MyCustomTagPrefix:HideWhenBlank>

So basically in this example when the comments field is empty, then the <p> tag as well as anything else inside the custom tag won’t be rendered. The tag will always allow the content to be rendered in edit mode though which means you can always add a value later. Thsi is nice and easy to implement and can help tidy up your page layouts a bit.