Knockout mapping - validate arrays

Question

How to set validation to Arrays using knockout validation?

My object definition

//c# code
public class Trophy
{
    public string Name { get; set; }
    public string Category { get; set; }
    public double PrizeMoney { get; set; }
}

public class Player
{
    public string Name { get; set; }
    public List<Trophy> Trophies { get; set; }
}

I am able to set validation like 'required' using ko validation for simple types like 'Name' but I cannot set to Trophies which is an array. For simple types I use as below

// javascript code 
var localModel = ko.mapping.fromJSON(getPlayerModelJson());

// Validation
localModel.Name.extend({ required: { message: 'Please enter first name' } });

Please let me know how to do for Name, Category and PrizeMoney with in Trophies?

I tried to make use of 'Customizing object construction using “create”' as mentioned in the
http://knockoutjs.com/documentation/plugins-mapping.html but it is creating a duplicate Trophies array item, for example if I have two list item in the Trophies the resulting object also has two items but it is duplicate of last item

// Java script code
var Trophies = function (data) {

    Name = ko.observable(data.Name).extend({ required: { message: 'Please enter name' } }),
    Category = ko.observable(data.Category),
    PrizeMoney = ko.observable(data.PrizeMoney)
}

var localModel = ko.mapping.fromJSON(getPlayerModelJson(), TrophiesMapping);

//Custom mapping
var TrophiesMapping = {
    'Trophies': {
        create: function (options) {
        return new Trophies(options.data);
        }
    }
}

All I wanted is validate the properties with in the array. Thanks

Corey Cole Corey Cole · Accepted Answer · 2013-07-19T02:29:05

Here's a JSFiddle using mapping. I think your problem might be the following line:

var localModel = ko.mapping.fromJSON(getPlayerModelJson(), TrophiesMapping);

I copied your code and was scratching my head as to why it didn't work until I changed it to

ko.mapping.fromJS(...)

Knockout mapping - validate arrays

2 Answers