Knockout Validation - How to show error messages

Question

We're using Knockout.js and the Knockout-validation plugin. When a user returns to a page that has validation errors, we want the error messages to display. Does anyone know if it's possible to trigger knockout validation without actually changing the bound answer?

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Answer 1

The solution is to call showAllMessages. If the view model has nested observables, be sure to set ko.validation.configure to use deep grouping because the default value is false.

Example:

viewModel.save = function()
{
    var result = ko.validation.group(viewModel, {deep: true});
    if (!viewModel.isValid()) 
    {
        alert("Please fix all errors before preceding");
        result.showAllMessages(true);

        return false;
    }

    //actually save stuff, call ajax, submit form, etc
}

Alternatively, you can replace !viewModel.isValid() with result().length > 0

Fractionize

Note that validatedObservable calls group behind the scenes and stores in errors property, so there is no need to do your own group. if (!viewModel.isValid()) { viewModel.errors.showAllMessages(); } – Australasia

How to hide them back? I noticed that this made the appearance of errors dynamic, i.e. show/hide as errors are validated. What if I would like to go back to showing them all in a go, lets say on a push of a button, like this example here. Thanks – Nehru