struts-sandbox/overdrive/Nexus/Core/Helpers/ViewHelper.cs

/*
 * Copyright 2005 The Apache Software Foundation.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
using System;
using System.Collections;
using Nexus.Core.Profile;
using Nexus.Core.Tables;

namespace Nexus.Core.Helpers
{
	/// <summary>
	/// Standard implementation of IViewHelper.
	/// </summary>
	/// 
	public abstract class ViewHelper : IViewHelper
	{
		/// <summary>
		/// Default setting for ListSuffix ["_list"].
		/// </summary>
		public const string LIST_SUFFIX = "_list";

		/// <summary>
		/// Default setting for NullIfEmpty [true].
		/// </summary>
		public const bool NULL_IF_EMPTY = true;

		/// <summary>
		/// Default setting for Prefix [""].
		/// </summary>
		public const string PREFIX = "";

		/// <summary>
		/// Default setting for SelectItemPrompt ["--v--"].
		/// </summary>
		public const string SELECT_ITEM_PROMPT = "--v--";

		#region Read and Bind 

		public void Execute()
		{
			Catalog.ExecuteView(Context);
		}

		public void Read(IDictionary input, bool nullIfEmpty)
		{
			if (input == null) return;
			ICollection keys = input.Keys;
			IDictionary criteria = Criteria;
			foreach (string key in keys)
			{
				string s = null;
				string o = Convert.ToString(input[key]);
				if (o!=null) s = o.Trim();
				if ((nullIfEmpty) && (s != null) && (s.Length == 0))
					criteria.Add(key, null);
				else
					criteria.Add(key, s);
			}
		}

		public IDictionary Criteria
		{
			get { return Context.Criteria; }
		}

		public virtual IList Outcome
		{
			get
			{
				IList result;
				object o = Criteria[Context.Command];
				if (o == null)
				{
					result = new ArrayList(1);
					result.Add(Criteria);
				}
				else
				{
					result = o as IList;
					if (result == null)
					{
						result = new ArrayList(1);
						result.Add(o);
					}
				}
				return result;
			}
		}

		#endregion

		#region Messages

		public IDictionary Alerts
		{
			get { return Context.Alerts; }
		}

		public bool HasAlerts
		{
			get { return Context.HasAlerts; }
		}

		public Exception Fault
		{
			get { return Context.Fault; }
		}

		public bool HasFault
		{
			get { return Context.HasFault; }
		}

		public virtual bool IsNominal
		{
			get { return (!HasAlerts && !HasFault); }
		}


		public IDictionary Hints
		{
			get { return Context.Hints; }
		}

		public bool HasHints
		{
			get { return Context.HasHints; }
		}

		#endregion 

		#region Messages (abstract) 

		public abstract string AlertsFor(string id);

		public abstract string AlertsText { get; }

		public abstract string HintsFor(string id);

		public abstract string HintsText { get; }

		#endregion

		#region Tables

		public IFieldTable FieldTable
		{
			get { return Context.FieldTable; }
		}

		private IList _FieldSet;

		public virtual IList FieldSet
		{
			get { return _FieldSet; }
			set { _FieldSet = value; }
		}

		#endregion 

		#region Options

		private string _Prefix = PREFIX;

		public string Prefix
		{
			get { return _Prefix; }
			set { _Prefix = value; }
		}

		private string _ListSuffix = LIST_SUFFIX;

		public string ListSuffix
		{
			get { return _ListSuffix; }
			set { _ListSuffix = value; }
		}

		private bool _NullIfEmpty = NULL_IF_EMPTY;

		public bool NullIfEmpty
		{
			get { return _NullIfEmpty; }
			set { _NullIfEmpty = value; }
		}

		private string _SelectItemPrompt = SELECT_ITEM_PROMPT;

		public string SelectItemPrompt
		{
			get { return _SelectItemPrompt; }
			set { _SelectItemPrompt = value; }
		}

		#endregion

		#region Properties

		private IRequestCatalog _Catalog;

		/// <summary>
		/// Provide the application object catalog for this Helper.
		/// </summary>
		/// <remarks>
		/// The Catalog is usually set through dependency injection. 
		/// The Catalog and Command must be set before calling other methods.
		/// </remarks>
		/// 
		public IRequestCatalog Catalog
		{
			get { return _Catalog; }
			set { _Catalog = value; }
		}

		private IRequestCommand _Command;

		/// <summary>
		/// Provide the command for this Helper.
		/// </summary>
		/// <remarks>
		/// The Command is usually set through dependency injection. 
		/// The Catalog and Command must be set before calling other methods.
		/// </remarks>
		/// 
		public IRequestCommand Command
		{
			get { return _Command; }
			set
			{
				_Command = value;
				_Context = Catalog.GetRequestContext(value);
			}
		}

		private IRequestContext _Context;

		/// <summary>
		/// Provide the all-important Context for this Helper.
		/// </summary>
		/// <remarks>
		/// The Context is obtained through reference to the Catalog and Command.
		/// All other properties and methods of the Helper refer to the Context, 
		/// making Context the cornerstone property.
		/// </remarks>
		/// 
		public virtual IRequestContext Context
		{
			get
			{
				if (_Context == null)
				{
					IRequestCommand rc = Command;
					if (rc == null) throw new ArgumentNullException("Command==null", "ViewHelper.Context");
					_Context = Catalog.GetRequestContext(rc);
				}
				return _Context;
			}
		}

		public IProfile Profile
		{
			get { return Context.Profile; }
			set { Context.Profile = value; }
		}

		#endregion 
	}
}