Extender 'ignoreInValidationGroup' to guard observables from being added to validation groups

Src/knockout.validation.js

@@ -215,6 +215,11 @@
                     // if object is observable then add it to the list
                     if (ko.isObservable(obj)) {
 
+                        //but not if it is flagged as ignore in group
+                        if(obj.ignoreInValidationGroup) {
+                            return; // we also do not add descendants
+                        }
+
                         //make sure it is validatable object
                         if (!obj.isValid) obj.extend({ validatable: true });
                         validatables.push(obj);
@@ -939,6 +944,14 @@
         return observable;
     };
 
+    //This extender can be used to flag a Knockout Observable to be ignored in validation groups.
+    //When the extender is set the observable will not be added to validation groups.
+    //Rules added to a flagged obserable still apply but the errors are not shown in any group.
+    ko.extenders['ignoreInValidationGroup'] = function (observable, enable) {
+        observable.ignoreInValidationGroup = enable;
+        return observable;
+    };
+
     function validateSync(observable, rule, ctx) {
         //Execute the validator and see if its valid
         if (!rule.validator(observable(), ctx.params === undefined ? true : ctx.params)) { // default param is true, eg. required = true

Tests/validation-tests.js

@@ -1038,6 +1038,18 @@ test('Issue #37 - Toggle ShowAllMessages', function () {
     ok(!vm.two.one.isModified(), "Level 2 is not modified");
     ok(!vm.three.two.one.isModified(), "Level 3 is not modified");
 });
+
+test('grouping ignores observables extended with ignoreInValidationGroup', function () {
+    var vm = {};
+    vm.firstName = ko.observable().extend({ required: true });
+    vm.lastName = ko.observable().extend({ required: 2 });
+    vm.allProperties = ko.observableArray([vm.firstName, vm.lastName]).extend({ ignoreInValidationGroup: true });
+
+    var errors = ko.validation.group(vm, { deep: true, observable: true });
+
+    equals(errors().length, 2, 'Grouping correctly finds only 2 invalid properties');
+});
+
 //#endregion
 
 //#region Conditional Validation