Sitecore 8 WebEditCommand for creating items in configurable locations

AddToLocation.cs

namespace NavArts.Sitecore.WebEdit
{
    using System;
    using System.Collections.Specialized;
    using global::Sitecore;
    using global::Sitecore.Configuration;
    using global::Sitecore.Data;
    using global::Sitecore.Data.Fields;
    using global::Sitecore.Data.Items;
    using global::Sitecore.Diagnostics;
    using global::Sitecore.Globalization;
    using global::Sitecore.SecurityModel;
    using global::Sitecore.Shell.Applications.WebEdit.Commands;
    using global::Sitecore.Shell.Framework.Commands;
    using global::Sitecore.Web.UI.Sheer;

    /// <summary>
    /// A configurable WebEditCommand to create Sitecore Items in a specified location.
    /// 
    /// Available Parameters:
    /// 
    /// * locationId (required) - Location to create the new item
    /// * templateId (required) - Template Id of the item to create
    /// * fieldId (optional) - If specified, will attempt to add the crated item id to a multilist field. Multilist field is assumed
    ///     to be on the 'Context Item' of the rendering (if datasource is set, the datasource item).
    /// </summary>
    [Serializable]
    public class AddToLocation : WebEditCommand
    {
        /// <summary>
        /// Main execution point of the WebEditCommand
        /// </summary>
        public override void Execute(CommandContext context)
        {
            Assert.ArgumentNotNull((object)context, "context");
            NameValueCollection parameters = new NameValueCollection();
            parameters["parent"] = context.Parameters["id"];
            parameters["master"] = context.Parameters["master"];

            // Get Language
            var itemUri = ItemUri.ParseQueryString();
            var language = context.Parameters["language"];

            if (String.IsNullOrEmpty(language) && itemUri != null)
            {
                language = itemUri.Language.ToString();
            }

            parameters["language"] = language;

            // Store the custom parameters 
            parameters["templateId"] = context.Parameters["templateId"] ?? String.Empty;
            parameters["locationId"] = context.Parameters["locationId"] ?? String.Empty;
            parameters["fieldId"] = context.Parameters["fieldId"] ?? String.Empty;

            Context.ClientPage.Start((object)this, "Run", parameters);
        }

        /// <summary>
        /// Handles the Postback of the Sheer Dialogs
        /// </summary>
        protected static void Run(ClientPipelineArgs args)
        {
            Assert.ArgumentNotNull((object)args, "args");
            var language = Language.Parse(args.Parameters["language"]);
            var parent = Context.ContentDatabase.Items[args.Parameters["parent"], language];

            Assert.IsNotNull((object)parent, typeof(Item));

            // Retrival of custom parameters
            var templateId = AddToLocation.GetSitecoreId(args.Parameters, "templateId");
            var locationId = AddToLocation.GetSitecoreId(args.Parameters, "locationId", parent.ID.ToString());
            var fieldId = AddToLocation.GetSitecoreId(args.Parameters, "fieldId");

            Assert.IsNotNull((object)templateId, typeof(ID));
            Assert.IsNotNull((object)locationId, typeof(ID));

            var locationItem = Context.ContentDatabase.GetItem(locationId);

            Assert.IsNotNull((object)locationItem, typeof(Item));

            var branch = Context.ContentDatabase.Branches[templateId.ToString(), language];

            Assert.IsNotNull((object)branch, typeof(BranchItem));

            if (args.IsPostBack)
            {
                if (!args.HasResult)
                {
                    return;
                }

                var item = Context.Workflow.AddItem(args.Result, branch, locationItem);

                // Add to a MultilistField
                if (!fieldId.IsNull)
                {
                    AddToLocation.AddToMultiField(parent, fieldId, item.ID);
                }

                SheerResponse.Eval(
                    "scForm.browser.getParentWindow(scForm.browser.getFrameElement(window).ownerDocument).location.reload(true)");
            }
            else if (!locationItem.Access.CanCreate())
            {
                Context.ClientPage.ClientResponse.Alert("You do not have permission to create an item here.");
            }
            else
            {
                SheerResponse.Input(String.Format("Enter a name for the new {0}:", branch.DisplayName), 
                    branch.DisplayName, 
                    Settings.ItemNameValidation,
                    Translate.Text("'$Input' is not a valid name."), Settings.MaxItemNameLength);

                args.WaitForPostBack();
            }
        }

        /// <summary>
        /// Gets a Sitecore Id from a NameValueCollection
        /// </summary>
        /// <param name="collection">Collection of Parameters</param>
        /// <param name="parameter">Parameter Key</param>
        /// <param name="defaultValue">Default value if no parameter under that key found. Default
        /// value is also returned if the value cannot be parsed into a </param>
        /// <returns>Sitecore Id</returns>
        private static ID GetSitecoreId(NameValueCollection collection, string parameter, string defaultValue = null)
        {
            if (collection == null || !collection.HasKeys() || String.IsNullOrEmpty(parameter))
            {
                return null;
            }

            var value = collection[parameter] ?? String.Empty;

            if (String.IsNullOrEmpty(value))
            {
                value = defaultValue;
            }

            ID output;

            ID.TryParse(value, out output);

            return output;
        }

        /// <summary>
        /// Adds a Sitecore Id to a Multilist Field
        /// <para>All parameters are required.</para>
        /// </summary>
        /// <param name="item">Context Item</param>
        /// <param name="fieldId">Multilist Field</param>
        /// <param name="value">Value to add to the multilist field</param>
        private static void AddToMultiField(Item item, ID fieldId, ID value)
        {
            if (item == null || fieldId.IsNull || value.IsNull)
            {
                return;
            }

            MultilistField multiListField = item.Fields[fieldId];

            if (multiListField == null)
            {
                return;
            }

            using (new SecurityDisabler())
            {
                using (new EditContext(item))
                {
                    multiListField.Add(value.ToString());
                }
            }
        }
    }
}

NavArts.Commands.config

<?xml version="1.0"?>
<configuration xmlns:patch="http://www.sitecore.net/xmlconfig/">
  <sitecore>    
    <commands>
      <!-- Registration of the AddToLocation command -->
      <command name="webedit:addtolocation" type="NavArts.Sitecore.WebEdit.AddToLocation,NavArts.Sitecore"/>
    </commands>
  </sitecore>
</configuration>

Excellent.Really Helpful.

In my solution, WebEditCommand is marked as "obsolete". What is the alternative? How can I get rid of the warning?

Which version of Sitecore are you using?

Awesome! Note: same issue as @tillito77. Using Sitecore 8.1 (rev. 160519).

This is marked as obsolete but unfortunately, I do not see an alternative. I would ignore the warning for now until Sitecore provides an update.

Also, make sure you are referencing the Sitecore.ExperienceEditor.dll

Confirmed with Sitecore that the [Obsolete] attribute was a mistake, and is removed on Sitecore 8.2 - update 2