Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Web/UI/WebControls/RequiredFieldValidator.cs

@@ -0,0 +1,80 @@
+//------------------------------------------------------------------------------
+// <copyright file="RequiredFieldValidator.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>                                                                
+//------------------------------------------------------------------------------
+
+/*
+ */
+
+namespace System.Web.UI.WebControls {
+
+    using System.ComponentModel;
+    using System.Web;
+    using System.Web.Util;
+
+
+    /// <devdoc>
+    ///    <para> Checks if the value of
+    ///       the associated input control is different from its initial value.</para>
+    /// </devdoc>
+    [
+    ToolboxData("<{0}:RequiredFieldValidator runat=\"server\" ErrorMessage=\"RequiredFieldValidator\"></{0}:RequiredFieldValidator>")
+    ]
+    public class RequiredFieldValidator : BaseValidator {
+
+
+        /// <devdoc>
+        ///    <para>Gets or sets the initial value of the associated input control.</para>
+        /// </devdoc>
+        [
+        WebCategory("Behavior"),
+        Themeable(false),
+        DefaultValue(""),
+        WebSysDescription(SR.RequiredFieldValidator_InitialValue)
+        ]                                         
+        public string InitialValue {
+            get { 
+                object o = ViewState["InitialValue"];
+                return((o == null) ? String.Empty : (string)o);
+            }
+            set {
+                ViewState["InitialValue"] = value;
+            }
+        }
+
+
+        /// <internalonly/>
+        /// <devdoc>
+        ///    AddAttributesToRender method
+        /// </devdoc>
+        protected override void AddAttributesToRender(HtmlTextWriter writer) {
+            base.AddAttributesToRender(writer);
+            if (RenderUplevel) {
+                string id = ClientID;
+                HtmlTextWriter expandoAttributeWriter = (EnableLegacyRendering || IsUnobtrusive) ? writer : null;
+                AddExpandoAttribute(expandoAttributeWriter, id, "evaluationfunction", "RequiredFieldValidatorEvaluateIsValid", false);
+                AddExpandoAttribute(expandoAttributeWriter, id, "initialvalue", InitialValue);
+            }
+        }
+
+
+        /// <internalonly/>
+        /// <devdoc>
+        ///    EvaluateIsValid method
+        /// </devdoc>
+        protected override bool EvaluateIsValid() {
+
+            // Get the control value, return true if it is not found
+            string controlValue = GetControlValidationValue(ControlToValidate);
+            if (controlValue == null) {
+                Debug.Fail("Should have been caught by PropertiesValid check");
+                return true;
+            }
+
+            // See if the control has changed
+            return(!controlValue.Trim().Equals(InitialValue.Trim()));
+        }                
+    }
+}
+