Please read the Part 1 of this blog entry to understand the Background if needed.

Ok Let’s create a Empty SharePoint Project in Visual Studio 2010 (SharePoint2010.Controls).

Add Mapped SharePoint folders (Right click on solution)

1) Control Templates

2) XML (Template/XML)

Add a new Class for our FileUploadCustomField (FileUploadCustomField.cs -> Namespace SharePoint2010.Controls.FileUploadCustomField).  Below is the code for this class.  We will use a Custom Property i.e., UploadDocumentLibrary to save the name of the document library to where the documents / images have to be uploaded (Selected from the drop down when creating the column).  Inherit this class from Microsoft.SharePoint.SPTextField.

 public FileUploadCustomField(SPFieldCollection fields, string fieldName) : base(fields, fieldName) { Init(); }
public FileUploadCustomField(SPFieldCollection fields, string typeName, string displayName) : base(fields, typeName, displayName) { Init(); }

private string _UploadDocumentLibrary = string.Empty;
public string UploadDocumentLibrary
{
get
{
return _UploadDocumentLibrary;
}
set
{
this.SetCustomProperty(“UploadDocumentLibrary”, value);
_UploadDocumentLibrary = value;
}
}

private void Init()
{
this.UploadDocumentLibrary = this.GetCustomProperty(“UploadDocumentLibrary”) + string.Empty;
}

public override void Update()
{
this.SetCustomProperty(“UploadDocumentLibrary”, this.UploadDocumentLibrary);
base.Update();
}

public override BaseFieldControl FieldRenderingControl
{
get
{
BaseFieldControl fieldControl = new FileUploadCustomFieldControl();
fieldControl.FieldName = InternalName;
return fieldControl;
}
}

Now let’s create the class FieldUploadCustomFieldControl under the same namespace as above. This will have to be Inherited from Microsoft.Sharepoint.WebControls.BaseFieldControl.  Below is the code for this class.

protected FileUpload UploadFileControl;
protected Button UploadButton;
protected Label StatusLabel;
protected HiddenField hdnFileName;

public override void Focus()
{
if (Field == null || this.ControlMode == SPControlMode.Display)
{ return; }
EnsureChildControls();
UploadFileControl.Focus();
}
public override object Value
{
get
{
EnsureChildControls();
if (hdnFileName.Value!=string.Empty)
return hdnFileName.Value;
else if (UploadFileControl.PostedFile != null)
{
string strFileName = UploadFileControl.PostedFile.FileName.Substring(UploadFileControl.PostedFile.FileName.LastIndexOf(“\\”) + 1);
return strFileName;
}
else
{
return null;
}
}
set
{
EnsureChildControls();
hdnFileName.Value = (string)this.ItemFieldValue;
StatusLabel.Text = “File: <a href=’” + (string)this.ItemFieldValue + “‘ target=’_blank’>View (” + (string)this.ItemFieldValue + “)</a>”;
}
}

protected override void CreateChildControls()
{
if (Field == null || this.ControlMode == SPControlMode.Display)
{ return; }

base.CreateChildControls();

UploadFileControl = (FileUpload)TemplateContainer.FindControl(“UploadFileControl”);
UploadButton = (Button)TemplateContainer.FindControl(“UploadButton”);
StatusLabel = (Label)TemplateContainer.FindControl(“StatusLabel”);
hdnFileName = (HiddenField)TemplateContainer.FindControl(“hdnFileName”);

UploadButton.Click += new EventHandler(UploadButton_Click);

if (hdnFileName.Value==string.Empty)
StatusLabel.Text = “Select file and click on upload.”;
else
StatusLabel.Text = “File: <a href=’” + hdnFileName.ToString() + “‘ target=’_blank’>View (” + hdnFileName.ToString() + “)</a>”;
Controls.Add(StatusLabel);
}

protected void UploadButton_Click(object sender, EventArgs e)
{
SPWeb sourceWeb;

SPSite sourceSite = SPControl.GetContextSite(Context);
sourceWeb = sourceSite.AllWebs["/"];
sourceWeb.AllowUnsafeUpdates = true;
FileUploadCustomField _field = (FileUploadCustomField)this.Field;
SPList objList = sourceWeb.Lists[_field.UploadDocumentLibrary];
SPFolder destFolder = objList.RootFolder;
try
{
if (UploadFileControl.PostedFile == null) return;
string strFileName = UploadFileControl.PostedFile.FileName.Substring(UploadFileControl.PostedFile.FileName.LastIndexOf(“\\”) + 1);

Stream fStream = UploadFileControl.PostedFile.InputStream;

SPFile objFile = destFolder.Files.Add(strFileName, fStream, true);
objFile.Item.UpdateOverwriteVersion();

StatusLabel.Text = “Upload File :: Success <a href=’” + “/” + objFile.ParentFolder + “/” + strFileName + “‘ target=’_blank’>View (” + “/” + objFile.ParentFolder + “/” + strFileName + “)</a>”;
hdnFileName.Value = “/” + objFile.ParentFolder + “/”  + strFileName;
sourceWeb.Dispose();
}
catch (Exception ex)
{
StatusLabel.Text = “Upload File :: Failed ” + ex.Message;
}

}

protected override string DefaultTemplateName
{
get
{
return “FileUploadControlTemplate”;
}
}

Now, see the DefaultTemplateName property that we are overriding.  We are returning “FileUploadControlTemplate” as the Template name.  Let’s create this template (an ASCX file that needs to go under Control templates folder – An user control).  Delete the .CS files for this as we don’t need them.

<%@ 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=”FileUploadControlTemplate” runat=”server”>
<Template>
<asp:FileUpload ID=”UploadFileControl” runat=”server” CssClass=”ms-ButtonHeightWidth” Width=”250px” />
<asp:Button ID=”UploadButton” runat=”server” CssClass=”ms-ButtonHeightWidth” Width=”50px” CausesValidation=”false” Text=”Upload”/>
<asp:Label ID=”StatusLabel” runat=”server” Width=”300px” />
<asp:HiddenField ID=”hdnFileName” runat=”server” />
</Template>
</SharePoint:RenderingTemplate>

Now we have Field and Field Control ready.  We also need to create an Editor control which will display the Drop down while creating the Column to show the Target document library into which the file has to be uploaded (We are using that in the Field Control above). Add a User Control to the solution (FileUploadFieldEditControl.ASCX).  Now move the .ASCX to the control templates folder and leave the .CS files under the solution as we want to Package them and Push the ASCX to the Control Templates folder.

ASCX File will be

<%@ 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” Inherits=”SharePoint2010.Controls.FileUploadFieldEditControl” %>
<%@ Register TagPrefix=”wssuc” TagName=”InputFormControl” Src=”~/_controltemplates/InputFormControl.ascx” %>
<%@ Register TagPrefix=”wssuc” TagName=”InputFormSection” Src=”~/_controltemplates/InputFormSection.ascx” %>
<wssuc:InputFormSection runat=”server” id=”UploadControl” Title=”Upload Control Configuration Section”>
<template_inputformcontrols>
<wssuc:InputFormControl runat=”server” LabelText=”Select document library”>
<Template_Control>
<asp:DropDownList ID=”ddlDocLibs” runat=”server” CssClass=”ms-ButtonheightWidth” Width=”250px” />
</Template_Control>
</wssuc:InputFormControl>
</template_inputformcontrols>
</wssuc:InputFormSection>

Declare the Drop Down Control in the Designer CS file.

protected DropDownList ddlDocLibs;

Add the Logic in the User Control Code behind file to populate the drop down with Document Libraries.  This class has to inherit from System.Web.UI.UserControl and the Interface Microsoft.SharePoint.WebControls.IFieldEditor.

FileUploadCustomField _field = null;

public bool DisplayAsNewSection
{
get { return true; }
}

public void InitializeWithField(SPField field)
{
this._field = field as FileUploadCustomField;
}

public void OnSaveChange(SPField field, bool isNewField)
{
FileUploadCustomField myField = field as FileUploadCustomField;
myField.UploadDocumentLibrary = ddlDocLibs.SelectedItem.Text;
}

protected override void CreateChildControls()
{
base.CreateChildControls();
SPListCollection objLists = SPContext.Current.Web.Lists;
foreach (SPList objList in objLists)
{
if (objList is SPDocumentLibrary)
ddlDocLibs.Items.Add(new ListItem(objList.Title, objList.Title));
}
if (!IsPostBack && _field != null)
{
if (!String.IsNullOrEmpty(_field.UploadDocumentLibrary))
FindControlRecursive<DropDownList>(this, “ddlDocLibs”).Items.FindByText(_field.UploadDocumentLibrary).Selected = true;
}
}

protected T FindControlRecursive<T>(Control rootControl, String id)
where T : Control
{
T retVal = null;
if (rootControl.HasControls())
{
foreach (Control c in rootControl.Controls)
{
if (c.ID == id) return (T)c;
retVal = FindControlRecursive<T>(c, id);
if (retVal != null) break;
}
}
return retVal;
}

Now, we have come to last step of building this control and deploying it.  Create an XML file under the XML folder and name it “FLDTYPES_FileUploadCustomField.xml”.

<?xml version=”1.0″ encoding=”utf-8″ ?>
<FieldTypes>
<FieldType>
<Field Name=”TypeName”>FileUploadCustomField</Field>
<Field Name=”TypeDisplayName”>File Upload Custom Field</Field>
<Field Name=”TypeShortDescription”>File Upload Custom Field</Field>
<Field Name=”ParentType”>Text</Field>
<Field Name=”UserCreatable”>TRUE</Field>
<Field Name=”ShowInListCreate”>TRUE</Field>
<Field Name=”ShowInSurveyCreate”>TRUE</Field>
<Field Name=”ShowInDocumentLibraryCreate”>TRUE</Field>
<Field Name=”ShowInColumnTemplateCreate”>TRUE</Field>
<Field Name=”FieldTypeClass”>SharePoint2010.Controls.FileUploadCustomField, $SharePoint.Project.AssemblyFullName$</Field>
<Field Name=”FieldEditorUserControl”>/_controltemplates/FileUploadFieldEditControl.ascx</Field>
<PropertySchema>
<Fields>
<Field Name=”UploadDocumentLibrary” DisplayName=”Select target Document Library” Type=”Text” Hidden=”True”/>
</Fields>
</PropertySchema>
</FieldType>
</FieldTypes>

And build and deploy the solution.