Create LookUp Field in SharePoint 2010 Programmatically Using VS 2012

Introduction

Today, in this article let's play around with one of the interesting and most useful concepts in SharePoint 2010.

Question: What is LookUp Field?

In simple terms "It is used to establish and maintain a relationship between the lists (source list and targeted list) across the server".

Step 1: Open SharePoint 2010 Central Administration and navigate to a specific site.

Step 2: Open up Visual Studio 2012 and try to select "SharePoint Visual Web Part" project, as in:

Step 3: Select "Deploy as a farm solution" as in the following and click on the "Finish" button, as in:

Step 4: The complete code of visualwebpart1usercontrol.ascx looks like this:

<%@ 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#" AutoEventWireup="true" CodeBehind="VisualWebPart1.ascx.cs"

    Inherits="LookUpFieldApp.VisualWebPart1.VisualWebPart1" %>

<center>

    <div>

        <table style="font-family: Verdana; text-align: center;">

            <tr>

                <td colspan="2">

                    <asp:label id="Label1" runat="server" text="LookUp Field - SharePoint 2010 via Visual Studio 2012"

                        font-bold="true" forecolor="Maroon" font-size="Large"></asp:label>

                </td>

            </tr>

            <tr>

                <td>

                    <asp:label id="Label2" runat="server" text="Please Enter LookUp Field Name:"></asp:label>

                </td>

                <td>

                    <asp:textbox id="TextBox1" runat="server"></asp:textbox>

                </td>

            </tr>

            <tr>

                <td>

                    <asp:label id="Label3" runat="server" text="Please Enter LookUp View Name:"></asp:label>

                </td>

                <td>

                    <asp:textbox id="TextBox2" runat="server"></asp:textbox>

                </td>

            </tr>

            <tr>

                <td colspan="2">

                    <asp:button id="Button1" runat="server" text="Create" forecolor="Orange" font-bold="true"

                        backcolor="Black" onclick="Button1_Click" width="116px" />

                </td>

            </tr>

            <tr>

                <td colspan="2">

                    <asp:label id="Label4" runat="server" font-bold="true"></asp:label>

                </td>

            </tr>

        </table>

    </div>

</center>

Step 5: The complete code of visualwebpart1usercontrol.ascx.cs looks like this:

using Microsoft.SharePoint;

using System;

using System.ComponentModel;

using System.Web.UI.WebControls.WebParts;namespace LookUpFieldApp.VisualWebPart1

{

    [ToolboxItemAttribute(false)]

    public partial class VisualWebPart1 : WebPart

    {

        // Uncomment the following SecurityPermission attribute only when doing Performance Profiling using

        // the Instrumentation method, and then remove the SecurityPermission attribute when the code is ready

        // for production. Because the SecurityPermission attribute bypasses the security check for callers of

        // your constructor, it's not recommended for production purposes.

        // [System.Security.Permissions.SecurityPermission(System.Security.Permissions.SecurityAction.Assert, UnmanagedCode = true)]

        public VisualWebPart1()

        {

        }

        protected override void OnInit(EventArgs e)

        {

            base.OnInit(e);InitializeControl();

        }

        protected void Page_Load(object sender, EventArgs e)

        {

            TextBox1.Focus();

        }

        protected void Button1_Click(object sender, EventArgs e)

        {

            getLook();

        }

        private void getLook()

        {

            if (string.IsNullOrEmpty(TextBox1.Text) || string.IsNullOrEmpty(TextBox2.Text))

            {

                Label4.Text = "Please Enter Some Values";

                Label4.ForeColor = System.Drawing.Color.Red;

            }

            else{SPWeb web = SPContext.Current.Web;

                SPList stuList = web.Lists["Student"];

                SPList cpnyList = web.Lists["Company"];

                string field = stuList.Fields.AddLookup(TextBox1.Text, cpnyList.ID, true);

                SPFieldLookup lookUp = new SPFieldLookup(stuList.Fields, field);

                lookUp.AllowMultipleValues = false;

                lookUp.LookupField = cpnyList.Fields["Company"].InternalName;lookUp.Indexed =true;lookUp.Update();

                SPView view = stuList.DefaultView;

                view.ViewFields.Add(TextBox2.Text);

                view.Update();

                Label4.Text = TextBox1.Text + " - LookUp Field Created Successfully";

                Label4.ForeColor = System.Drawing.Color.Green;

                TextBox1.Text = string.Empty;

                TextBox2.Text = string.Empty;

            }

        }

    }

}

Step 6: Deploy the solution file and add the new webpart to a SharePoint site.

Step 7: The output of the application looks like this:

 

Step 8: The company list of the application looks like this:

 

Step 9: Data entering output of the application looks like this:

 

Step 10: Look up field created output of the application looks like this:

 

 

I hope this article is useful for you.