Form Validation 101

Forms validation

Ad-hoc validation in render

Validation in models

Link validation

Links carry additional validationError field for validation purposes (to be used inside of custom UI controls). It's populated automatically for links created from models and collection, utilizing nestedtypes validation mechanics. Therefore, if model attribute has any check attached, its link will carry its validationError object.

var M = Nested.Model.extend({
    defaults : {
        attr : Number.has.check( x => x > 0, 'attr should be positive' )    
    }
});

...

var m = new M({ attr : -1 });
var attrLink = m.getLink( 'attr' );

console.assert( m.value === -1 );
console.assert( m.validationError === 'attr should be positive' );

It's possible to use ad-hoc validation in component's render method with link.check method.

var link = model.getLink( 'something' )
                .check( x => x > 0, 'Shoulld be positive' )
                .check( x => x < 10, 'Shoulld be lesser than 10' );

Failed checks will populate link's validationError with first failed check's message.