SharePoint Dragons

Camlex.NET simplifies the creation of CAML queries: http://camlex.codeplex.com/ It’s not very popular yet, but it’s interesting. It seems to be offering an easier, more familiar way to construct CAML queries on the fly using lambda expressions and a fluent interface. Not sure how this compares to SPMetal, which requires you to generate classes beforehand before you’ll be able to use Linq to query object structures (which then get translated to CAML). At first glance SPMetal seems to be even easier, because it supports strong typing and concurrency conflict resolution. Tell us what you think?

This post contains the code required for making a SharePoint 2010 web part that uses an editor part that contains a drop down list.

Here’s the code for the web part editor part:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.WebControls;

namespace SharePointProject3.WebPart1
{
    public class WebPart1EditorPart : EditorPart
    {
        // Reference to the web part that uses this editor part, the parent web part needs to implement the IWebEditable interface to support custom editing controls
        protected WebPart1 ParentWebPart { get; set; }
        protected DropDownList EditorChoices { get; set; }

        /// <summary>
        /// Does editor part init settings
        /// </summary>
        public WebPart1EditorPart()
        {
            Title = “Make a choice – good name here”;
        }

        /// <summary>
        /// Creates the dll
        /// </summary>
        protected override void CreateChildControls()
        {
            EditorChoices = new DropDownList();
            EditorChoices.Items.Add(new ListItem(“AAA”, “1”));
            EditorChoices.Items.Add(new ListItem(“BBB”, “2”));
            EditorChoices.Items.Add(new ListItem(“CCC”, “3”));
            Controls.Add(EditorChoices);

            base.CreateChildControls();
            ChildControlsCreated = true;
        }

        /// <summary>
        /// Reads current value from parent web part and show that in the ddl
        /// </summary>
        public override void SyncChanges()
        {
            EnsureChildControls();
            ParentWebPart = WebPartToEdit as WebPart1;

            if (ParentWebPart != null && WebPartManager.Personalization.Scope == PersonalizationScope.Shared)
            {
                ListItem item = EditorChoices.Items.FindByValue(ParentWebPart.MyEditorPartChoice);
                if (item != null) item.Selected = true;
            }
        }

        /// <summary>
        /// Applies change in editor part ddl to the parent web part
        /// </summary>
        /// <returns></returns>
        public override bool ApplyChanges()
        {
            try
            {
                EnsureChildControls();
                ParentWebPart = WebPartToEdit as WebPart1;

                if (ParentWebPart != null && WebPartManager.Personalization.Scope == PersonalizationScope.Shared)
                {
                    ParentWebPart.MyEditorPartChoice = EditorChoices.SelectedValue;
                }

                // The operation was succesful
                return true;
            }
            catch
            {
                // Because an error has occurred, the SyncChanges() method won’t be invoked.
                return false;
            }
        }
    }
}

Here’s the code for the web part itself:

using System;
using System.ComponentModel;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using Microsoft.SharePoint;
using Microsoft.SharePoint.WebControls;
using System.Collections.Generic;

namespace SharePointProject3.WebPart1
{
    [ToolboxItemAttribute(false)]
    public class WebPart1 : WebPart, IWebEditable
    {
        protected override void CreateChildControls()
        {
            var lbl = new Label();

            if (MyEditorPartChoice == null)
                lbl.Text = “Make a choice first”;
            else
                lbl.Text = “The value from the editor part choice: ” + MyEditorPartChoice;
           
            Controls.Add(lbl);
        }

        /// <summary>
        /// Contains the value of the choice in the editor part drop down list
        ///
        /// Set the Personalizable attribute to true,
        /// to allow for personalization of tabs by users.
        /// This causes  this property to be shown in the web part tool pane and lets SharePoint take care of the storage/retrieval of this property in the SharePoint content database.
        /// </summary>
        [Personalizable(true)]
        public string MyEditorPartChoice { get; set; }

        /// <summary>
        /// Creates custom editor parts here and assigns a unique id to each part
        /// </summary>
        /// <returns>All custom editor parts used by this web part</returns>
        EditorPartCollection IWebEditable.CreateEditorParts()
        {
            var editors = new List<EditorPart>();           
            var editorPart = new WebPart1EditorPart();
            editorPart.ID = ID + “_editorPart”;
            editors.Add(editorPart);

            return new EditorPartCollection(editors);
        }

        /// <summary>
        /// Returns parent web part to editor part
        /// </summary>
        object IWebEditable.WebBrowsableObject
        {
            get { return this; }
        }
    }
}