KnockoutJS Validation - nested ViewModel as validatedobservable

Question

I have a KnockoutJS viewmodel that acts as a "master" viewmodel for several modular viewmodels. These modular vm's utilize knockout validated properties for their own form validations. I would like to make these viewmodels validatedObservable in the master viewmodel, so I can simply check each if isValid is true:

function MasterViewModel() {
    var self = this;

    self.addUserViewModel = ko.validatedObservable(new AddUserViewModel());
}

function AddUserViewModel() {
    var self = this;
    self.username = ko.observable().extend({ required: true });

    self.addUser = = function () {
        if(self.isValid()) {
            // Perform add user logic here
        }
    }.bind(self);
}

However, the isValid method does not exist for the child viewmodel when I attempt to call it. Is there an issue with adding a validatedObservable property that is a function?

Answer 1

The isValid is added by the function validatedObservable and will therefore only be available inside the MasterViewModel.

You could use ko.validation.group when you want to check if the model is valid inside the model itself:

function AddUserViewModel() {
    var self = this;
    self.username = ko.observable().extend({ required: true });

    var errors = ko.validation.group(self, { deep: true });
    self.addUser = = function () {
        if (!errors().length) {
            // Perform add user logic here
        }
    };
}