LinqDataSource Cache

/// <summary> /// A LinqDataSource that provides caching for Linq queries. /// </summary> public class LinqCacheDataSource : LinqDataSource { /// <summary> /// Initializes a new instance of the <see cref="LinqCacheDataSource"/> class. /// </summary> public LinqCacheDataSource() : base() { this.Selecting += new EventHandler<LinqDataSourceSelectEventArgs>(OnSelecting); this.Selected += new EventHandler<LinqDataSourceStatusEventArgs>(OnSelected); } private void OnSelecting(object sender, LinqDataSourceSelectEventArgs e) { if (!EnableCache) return; string key = GetKey(); object source = Context.Cache[key]; if (source == null) return; Debug.WriteLine("Cache Hit: " + key); e.Result = source; } private void OnSelected(object sender, LinqDataSourceStatusEventArgs e) { if (!EnableCache) return; if (e.Exception != null || e.Result == null) return; string key = GetKey(); object source = Context.Cache[key]; if (source != null) return; Debug.WriteLine("Cache Insert: " + key); Context.Cache.Insert(key, e.Result, null, DateTime.Now.AddSeconds(Duration), Cache.NoSlidingExpiration); } private string GetKey() { StringBuilder sb = new StringBuilder(); sb.Append(this.ContextTypeName); sb.Append(" from "); sb.Append(this.TableName); if (!string.IsNullOrEmpty(this.Select)) { sb.Append(" select "); sb.Append(this.Select); } if (!string.IsNullOrEmpty(this.Where)) { sb.Append(" where "); sb.Append(this.Where); } if (!string.IsNullOrEmpty(this.OrderBy)) { sb.Append(" OrderBy "); sb.Append(this.OrderBy); } return sb.ToString(); } /// <summary> /// Gets or sets a value indicating whether query caching is enabled. /// </summary> [DefaultValue(true)] [Category("Cache")] [Description("Enable caching the linq query result.")] public bool EnableCache { get { object result = this.ViewState["EnableCache"]; if (result != null) return (bool)result; return true; } set { this.ViewState["EnableCache"] = value; } } /// <summary> /// Gets or sets the time, in seconds, that the query is cached. /// </summary> [DefaultValue(30)] [Category("Cache")] [Description("The time, in seconds, that the query is cached.")] public int Duration { get { object result = this.ViewState["Duration"]; if (result != null) return (int)result; return 30; } set { this.ViewState["Duration"] = value; } } }