How to validate an array?

Question

I am trying to use knockout validation lib to validate an array of objects. It is not straightforward to me how to form a validation group for an array of observables. The only way I managed to make it work is like this (JSFIDDLE included):

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

var viewModel = function() {
    var self = this;

    self.notes = ko.observableArray([new Note(), new Note()]);

    self.validatedObservables = function() {
        var arr = [];
        ko.utils.arrayForEach(self.notes(), function(note) {
            arr.push(note.name);
        });
        return arr;
    };

    self.errors = ko.validation.group(self.validatedObservables());

    self.submit = function () {
        if (self.errors().length != 0) {
            self.errors.showAllMessages();
        }
    };

};

ko.applyBindings(new viewModel());

It seems like my approach is unnecessarily verbose. According to the source code you can simply pass an observable to ko.validation.group:

self.errors = ko.validation.group(self.notes());

But this doesn't work.

Answer 1

There is a configuration option for the grouping to be deep (recursive). It can be set either globally with ko.validation.init( { grouping: { deep: true } } ) or in the group call itself, e.g.: self.errors = ko.validation.group( self.notes(), {deep: true} );

Updated fiddle here: http://jsfiddle.net/KHFn8/4116/

BTW, the way you did it could be written in much shorter form:

self.errors = ko.validation.group(
    ko.utils.arrayMap(self.notes(), function(note) { return note.name }));

Edit: My fiddle no longer works with the latest version of KO validation. Here is the same fiddle using the latest version at the time I gave the answer (June 2012): http://jsfiddle.net/KHFn8/4117/