Creating a Custom Field Type for SharePoint (Email Validation Field)

1. Open the Email.Field.cs file.
2. Add the following name spaces.

   using Microsoft.SharePoint;
   using Microsoft.SharePoint.WebControls;
   using Microsoft.SharePoint.Security;
   using System.Windows.Controls;
   using System.Globalization;
   using System.Runtime.InteropServices;
   using System.Security.Permissions;

3. Add the following statements. These enables our class implementation to reference other classes you create in later steps. Until you create those classes you may see compiler warnings about these statements. Don't worry about that; we are moving to that in a following step.

   using Control.Validation.WebControls;
   using Control.System.Windows.Controls;

4. Please find the following updated code.

   using System;
   using System.Collections.Generic;
   using System.Linq;
   using System.Text;
   using Microsoft.SharePoint;
   using Microsoft.SharePoint.WebControls;
   using Microsoft.SharePoint.Security;
   using System.Windows.Controls;
   using System.Globalization;
   using System.Runtime.InteropServices;
   using System.Security.Permissions;
   using Email.SharePoint.WebControls;
   using Email.System.Windows.Controls;
   using System.IO;
   using System.Web;
   using System.Web.UI;
   namespace Email.SharePoint
   {
       public class EmailField : SPFieldText
       {
           public EmailField(SPFieldCollection fields, string fieldName)
               : base(fields, fieldName)
           {
           }
           public EmailField(SPFieldCollection fields, string typeName, string displayName)
               : base(fields, typeName, displayName)
           {
           }
           public override BaseFieldControl FieldRenderingControl
           {
               [SharePointPermission(SecurityAction.LinkDemand, ObjectModel = true)]
               get
               {
                   BaseFieldControl fieldControl = new EmailFieldControl();
                   fieldControl.FieldName = this.InternalName;
                   return fieldControl;
               }
           }
           public override string GetValidatedString(object value)
           {
               if ((this.Required == true) && ((value == null)|| ((String)value == "")))
               {
                   throw new SPFieldValidationException(this.Title + " must have a value.");
               }
               else
               {
                   Email10ValidationRule rule = new Email10ValidationRule();
                   ValidationResult result = rule.Validate(value, CultureInfo.InvariantCulture);
                   if (!result.IsValid)
                   {
                       throw new SPFieldValidationException((String)result.ErrorContent);
                   }
                   else
                   {
                       return base.GetValidatedString(value);
                   }
               }
           }
       }
   }

Creating the Field Rendering Control

Please replace the code in EmailFieldControl.ascx.cs we created in step 20 with the following.

using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Runtime.InteropServices;
using Microsoft.SharePoint;
using Microsoft.SharePoint.WebControls;
namespace Email.SharePoint.WebControls
{
    public class EmailFieldControl : TextField
    {
        protected Label EmailPrefix;
        protected Label EmailValueForDisplay;
        protected override string DefaultTemplateName
        {
            get
            {
                if (this.ControlMode == SPControlMode.Display)
                {
                    return this.DisplayTemplateName;
                }
                else
                {
                    return "EmailFieldControl";
                }
            }
        }
        public override string DisplayTemplateName
        {
            get
            {
                return "EmailFieldControlForDisplay";
            }
            set
            {
                base.DisplayTemplateName = value;
            }
        }
        protected override void CreateChildControls()
        {
            if (this.Field != null)
            {
                base.CreateChildControls();
                //   this.EmailPrefix = (Label)TemplateContainer.FindControl("EmailPrefix");
                this.textBox = (TextBox)TemplateContainer.FindControl("TextField");
                this.EmailValueForDisplay = (Label)TemplateContainer.FindControl("EmailValueForDisplay");
            }
            if (this.ControlMode != SPControlMode.Display)
            {
                if (!this.Page.IsPostBack)
                {
                    if (this.ControlMode == SPControlMode.New)
                    {
                        textBox.Text = "";
                    }
                }
            }
            else
            {
                EmailValueForDisplay.Text = (String)this.ItemFieldValue;
            }
        }
        public override object Value
        {
            get
            {
                EnsureChildControls();
                return base.Value;
            }
            set
            {
                EnsureChildControls();
                base.Value = (String)value;
            }
        }
    }
}

Creating the Field Rendering Template

1. Open the EmailControl.ascx file.
2. The following directives are already in the file.

   <%@ Assembly Name="$SharePoint.Project.AssemblyFullName$" %>
   <%@ Assembly Name="Microsoft.Web.CommandUI, Version=14.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c" %>
   <%@ Register Tagprefix="SharePoint" Namespace="Microsoft.SharePoint.WebControls" Assembly="Microsoft.SharePoint, Version=14.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c" %>
   <%@ Register Tagprefix="Utilities" Namespace="Microsoft.SharePoint.Utilities" Assembly="Microsoft.SharePoint, Version=14.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c" %>
   <%@ Register Tagprefix="asp" Namespace="System.Web.UI" Assembly="System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" %>
   <%@ Import Namespace="Microsoft.SharePoint" %>
   <%@ Register Tagprefix="WebPartPages" Namespace="Microsoft.SharePoint.WebPartPages" Assembly="Microsoft.SharePoint, Version=14.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c" %>
   <%@ Control Language="C#" %>
   <SharePoint:RenderingTemplate ID="EmailFieldControl" runat="server">
     <Template>
       <table>
       <tr>
       <td >
       <asp:Label ID="EmailPrefix"  runat="server" />
       </td>
        <td>
      <asp:TextBox id="TextField" runat="server" Width="50%" ></asp:TextBox>
      </td>
        </tr>
        <tr>
      </tr>
      </table>
     </Template>
   </SharePoint:RenderingTemplate> 
   <SharePoint:RenderingTemplate ID="EmailFieldControlForDisplay" runat="server">
     <Template>
       <asp:Label ID="EmailValueForDisplay" runat="server" />
     </Template>
   </SharePoint:RenderingTemplate>

3. Below this markup is a <%@ Control directive that makes reference to files that you deleted in an earlier step and contains other attributes that are not used in this project. Replace it with the following simplified directive. I have already done this change in the above code.

   <%@ Control Language="C#" %>

Creating the Field Type Definition

1. In Visual Studio, build the project. The project is not finished, but you need to do a build at this time to generate a GUID and a Public Key Token for the assembly.
2. Open the fldtypes_EmailField.xml file and replace it's contents with the following markup

   <?xml version="1.0" encoding="utf-8" ?>
   <FieldTypes>
    <FieldType>
   <Field Name="TypeName">Email</Field>
    <Field Name="ParentType">Text</Field>
    <Field Name="TypeDisplayName">Email</Field>
    <Field Name="TypeShortDescription">Email Validation Text</Field>
    <Field Name="UserCreatable">TRUE</Field>
    <Field Name="ShowOnListCreate">TRUE</Field>
   <Field Name="ShowOnSurveyCreate">TRUE</Field>
    <Field Name="ShowOnDocumentLibraryCreate">TRUE</Field>
   <Field Name="ShowOnColumnTemplateCreate">TRUE</Field>
   <Field Name="FieldTypeClass">Email.SharePoint.EmailField,$SharePoint.Project.AssemblyFullName$</Field>
   </FieldType>
   </FieldTypes>

Creating the XSLT Style sheet

Open the fldtypes_EmailField.xsl file and replace the code.

<xsl:stylesheet xmlns:x="http://www.w3.org/2001/XMLSchema"
                xmlns:d="http://schemas.microsoft.com/sharepoint/dsp"
                version="1.0"
                exclude-result-prefixes="xsl msxsl ddwrt"
                xmlns:ddwrt="http://schemas.microsoft.com/WebParts/v2/DataView/runtime"
                xmlns:asp="http://schemas.microsoft.com/ASPNET/20"
                xmlns:__designer="http://schemas.microsoft.com/WebParts/v2/DataView/designer"
                xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
                xmlns:msxsl="urn:schemas-microsoft-com:xslt"
                xmlns:SharePoint="Microsoft.SharePoint.WebControls"
                xmlns:ddwrt2="urn:frontpage:internal">
  <xsl:template match="FieldRef[@Name = 'Email']" mode="Text_body">
    <xsl:param name="thisNode" select="." />
    <span style="background-color:lightgreen;font-weight:bold">
      <xsl:value-of select="$thisNode/@*[name()=current()/@Name]" />
    </span>
  </xsl:template >
</xsl:stylesheet>

Build and Test the Custom Field Type

1. Select Deploy on the Build menu. This automatically rebuilds the assembly, deploys the assembly to the GAC, deploys the ascx file to %ProgramFiles%\Common Files\Microsoft Shared\web server extensions\14\TEMPLATE\ControlTemplates, deploys the fldtypes*.xml file to %ProgramFiles%\Common Files\Microsoft Shared\web server extensions\14\TEMPLATE\XML, deploys the fldtypes*.xsl file to %ProgramFiles%\Common Files\Microsoft Shared\web server extensions\14\TEMPLATE\LAYOUTS\XSL, and recycles the Web application.
2. Go to site actions -->Site Settings
3. Click on site libraries and list
   
   
   
4. Click on Create new Content
5. Create a custom list named Test For Email
   
   
   
6. From the ribbon click on create column
   
   
   
7. You will see that our custom field is added there successfully. Give the details as shown below to add a custom column to your list.
   
   
   
8. From the screen shot shown below you can see our custom email field in action.
   
   
   
   

The data is added as shown below.

For more details, you can refer to the article of creating custom field for SharePoint 2010 in MSDN.