"create" KO mapping option for nested objects not used when primary "create" is specified

Question

I have the following:

var CardViewModel = function (data) {
    ko.mapping.fromJS(data, {}, this);
    this.editing = ko.observable(false);
    this.edit = function() {
        debugger;
        this.editing(true);
    };

};


var mapping = {

    'cards': {
        create: function (options) {
            debugger;  // Doesn't ever reach this point unless I comment out the create method below
            return new CardViewModel(options.data);

        }
    },

    create: function(options) {
        //customize at the root level.  
        var innerModel = ko.mapping.fromJS(options.data);
        //debugger;
        innerModel.cardCount = ko.computed(function () {
            //debugger;
            return innerModel.cards().length;
        });

        return innerModel;
    }
};

var SetViewModel = ko.mapping.fromJS(setData, mapping);
debugger;
ko.applyBindings(SetViewModel);

When I run this, the 'cards' method never gets hit, so those edit properties in the CardViewModel aren't available. I can hit that debugger if I comment out the "create" method, but I need both. Any idea what's going on?

DaveB · Accepted Answer · 2013-03-24 07:47:18Z

1

'cards' is not a valid Javascript variable name. Try something else without the single quotes.

You will also need to edit your CardViewModel code as this in the inner function refers to the inner function and will not see the knockout observable in the outer function.

var CardViewModel = function (data) {
    var self = this;
    ko.mapping.fromJS(data, {}, this);
    this.editing = ko.observable(false);
    this.edit = function() {
        debugger;
        self.editing(true);
    };
};

answered Mar 24, 2013 at 7:47

DaveB

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3 Comments

JakeP Over a year ago

Thanks Dave. I'm a bit confused about the 'cards' - I'm following the example here for defining the "children" subarray: knockoutjs.com/documentation/plugins-mapping.html In my case, 'cards' is an array. This method does get hit when I remove the 'create' method.

dubRun Over a year ago

Jake, did this answer your original answer? I'm in a similar spot right now and removing the single quotes makes no difference. I can never use a create for a child object unless I remove the main create.

Doug Moore Over a year ago

I don't understand why this is accepted. This is clearly part of the knockout syntax as noted by @JakeP. Also, nowhere in the modified CaredViewModel does it reference the mapping.

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