Knockout Validation - How to show error messages

CBlack picture CBlack · Aug 23, 2012 · Viewed 27.9k times · Source

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

CBlack picture CBlack · Aug 24, 2012

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