Asset Picker field type

In one of my project, I had to create a field type in MOSS with Asset picker functionality. Custom field types are very useful when you are creating custom functionality in MOSS 2007. The following example shows how to provide a functionality to select the document/list item/ from the site. The would be helpful to the user selecting the URL rather typing everything (there is a possibility of typos :) ). We are going to use 'AssetUrlSelector' class from Microsoft.SharePoint.Publishing.WebControls namespace for the purpose.

Create a custom field class by inheriting from SPFieldText class.

public class RelationshipField : SPFieldText {
// Methods

public RelationshipField(SPFieldCollection fields, string fieldName) : base(fields, fieldName) {}

public RelationshipField(SPFieldCollection fields, string typeName, string displayName) : base(fields, typeName, displayName)

{}

// Properties

public override BaseFieldControl FieldRenderingControl

{

get

{

BaseFieldControl control = new RelationshipFieldControl();

control.FieldName = base.InternalName;

return control;

}

}

}

Create a control class by inherting from BaseFieldControl class. and also need to include the following namespaces.

using Microsoft.SharePoint;

using Microsoft.SharePoint.Publishing.WebControls;

using Microsoft.SharePoint.WebControls;

Here is how the control creation goes:

public class RelationshipFieldControl : BaseFieldControl

{

protected AssetUrlSelector urlSelector;
protected override void OnLoad(EventArgs e)

{

base.OnLoad(e);
// Set the value if this is a postback.

if (this.Page.IsPostBack && base.ControlMode == SPControlMode.Edit)

{

this.ListItemFieldValue = urlSelector.AssetUrl;

}

}
protected override void CreateChildControls()

{

base.CreateChildControls();
// Add the asset picker when in edit mode.

if (base.ControlMode == SPControlMode.Edit)

{

urlSelector = new AssetUrlSelector();

this.Controls.Add(urlSelector);

}

}
protected override void Render(HtmlTextWriter output)

{
// If this is edit mode and has a value, set the picker.

if (base.ControlMode.Equals(SPControlMode.Edit)

&& this.ListItemFieldValue != null)

{

this.urlSelector.AssetUrl = this.ListItemFieldValue.ToString();

}

base.Render(output);

}

}



To register the custom field created above, you need to create a field type definition file as show below. And this xml file needs to be copied to 12\TEMPLATE\XML directory to recognize by MOSS.



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Happy Coding... !!




~ Gangadhar Kotu