Use FormattedString with FormField in view/edit form

Question

I am trying to format a Sharepoint:FormField in a view/edit form and used FormattedString, but it doesn´t work. I do this because I would like to display a number without comma separator.

<SharePoint:FormattedString FormatText="Text in field: {0}">
<SharePoint:FormField Grid.Column="0" Grid.Row="0" ControlMode="Display"
FieldName="EmployeeNumber" IncludeDescription="True"/>
</SharePoint:FormattedString>

The FormField seems not to be rendered.

Answer 1

It renders nothing if FormatText is null or empty. Look at the code:

protected override void Render(HtmlTextWriter output)
{
    if (!string.IsNullOrEmpty(this.FormatText))
    {
        string[] args = new string[this.Controls.Count];
        int index = 0;
        StringBuilder sb = new StringBuilder();
        HtmlTextWriter writer = new HtmlTextWriter(new StringWriter(sb, CultureInfo.InvariantCulture));
        foreach (Control control in this.Controls)
        {
            if (!(control is LiteralControl))
            {
                sb.Length = 0;
                control.RenderControl(writer);
                writer.Flush();
                args[index] = sb.ToString();
                index++;
            }
        }
        string format = null;
        switch (this.EncodeMethod)
        {
            case SPEncodeMethod.NoEncode:
                format = this.FormatText;
                break;

            case SPEncodeMethod.HtmlEncode:
                format = SPHttpUtility.HtmlEncode(this.FormatText);
                break;

            case SPEncodeMethod.HtmlEncodeAllowSimpleTextFormatting:
                format = SPHttpUtility.HtmlEncodeAllowSimpleTextFormatting(this.FormatText);
                break;

            case SPEncodeMethod.EcmaScriptStringLiteralEncode:
                format = SPHttpUtility.EcmaScriptStringLiteralEncode(this.FormatText);
                break;
        }
        output.AddAttribute(HtmlTextWriterAttribute.Id, this.ClientID);
        output.RenderBeginTag(HtmlTextWriterTag.Span);
        string str2 = string.Empty;
        try
        {
            str2 = string.Format(CultureInfo.InvariantCulture, format, args);
        }
        catch (FormatException)
        {
            str2 = string.Format(CultureInfo.InvariantCulture, SPUtility.EscapeForStringFormat(format), args);
        }
        output.Write(str2);
        output.RenderEndTag();
    }
}