Validation is working on Settings -> Indexers again.

NzbDrone.Web/Scripts/conditional-validation.js

@@ -0,0 +1,43 @@
+/// <reference path="jquery-1.4.4-vsdoc.js" />
+/// <reference path="jquery.validate.unobtrusive.js" />
+
+$.validator.addMethod('requiredif',
+    function (value, element, parameters) {
+        var id = '#' + parameters['dependentproperty'];
+
+        // get the target value (as a string, 
+        // as that's what actual value will be)
+        var targetvalue = parameters['targetvalue'];
+        targetvalue =
+          (targetvalue == null ? '' : targetvalue).toString();
+
+        // get the actual value of the target control
+        // note - this probably needs to cater for more 
+        // control types, e.g. radios
+        var control = $(id);
+        var controltype = control.attr('type');
+        var actualvalue =
+            controltype === 'checkbox' ?
+            (control.attr('checked') == "checked" ? "true" : "false") :
+            control.val();
+
+        // if the condition is true, reuse the existing 
+        // required field validator functionality
+        if (targetvalue === actualvalue)
+            return $.validator.methods.required.call(
+              this, value, element, parameters);
+
+        return true;
+    }
+);
+
+$.validator.unobtrusive.adapters.add(
+    'requiredif',
+    ['dependentproperty', 'targetvalue'],
+    function (options) {
+        options.rules['requiredif'] = {
+            dependentproperty: options.params['dependentproperty'],
+            targetvalue: options.params['targetvalue']
+        };
+        options.messages['requiredif'] = options.message;
+    });