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?

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