Support for Knockout extenders (client converters)

[darilek]

Basic support for knockout extenders.
Steps to activate extender:

1. decorate specified property with ClientExtenderAttribute
2. create and register Knockout extender in javascript
3. use extender when declare Knockout binding ie. data-bind='value: PropertyName.ExtenderName'

This patch is primarily intended for component developers (Knockout wrappers). It should be easy to expand support to the DotVVM binding syntax

[exyi]

Thank you, it seems to be pretty cool.
Maybe it may be useful to have more than one extender on a single property or to pass a parameter to the extender (not just true), so we can probably transfer the entire object in options like {myExtender1: "parameter value", anotherExtender: true} and the attribute should have a property for the parameter

I think we can merge it, @tomasherceg?

[darilek]

• hardcoded parameter value is my mistake. I do not use parameters for now, but I agree, it shloud be supported
• I did not tried apply more then one extender on observable property. But it is possible. Syntax is

this.propertyName = ko.observable(value).extend({ extender1 : param1, extender2 : param2})

[darilek]

I will try to prepare a patch which covers the points discussed above

[tomasherceg]

Awesome. When it's ready, we can merge it and write some tests for this.

[darilek]

Hello, I've prepared second patch which covers @exyi requests :-)

Small example:

// C# view model class
public class ViewModel 
{
   // atribute has parameters: name, parameter value (optional) and order (optional)
   [ClientExtender("extender1", "hello world", 2]
   [ClientExtender("extender2", true, 1]
   public string PropertyName { get; set; }
}

Client side serialializer has ability chain declared extenders by specified order

// result of executed code on client side
this.PropertyName = ko.observable(value).extend({ extender2 : true}).extend({extender1 : "hello world"});

[darilek]

I've added the first (very simple) client extender sample - password strength indicator

[exyi]

Sorry it took so long time, but finally merged. Thank you.