CODEWITHSUNDEEP
javascriptknockout.jsasp.net-web-apibreezedurandal
zam6ak
zam6ak

Reputation: 7259

How do I automate extending Knockout observables from entities returned by Breeze query?

I am using Konckout, Breeze JS, Durandal JS, ASP.NET Web API but my question is specific to Breeze and Knockout.

How do I automate extending Knockout observables from entities returned by Breeze query?

I have a list of Customers being returned via Breeze and they have DB specific fields which I would like to make presentable. In particular I want:

From what I have read (please let me know if I am wrong), the way to do this is not to use custom bindings anymore but to extend KO observables using .extend() function.

My dataservice.js has following Breeze query that accepts observable and sets it to data results.

// -- snip --
        function getCustomers(koCustomers) {
            var query = breeze.EntityQuery
                .from('Customers');

            return manager.executeQuery(query)
                .then(querySucceeded)
                .fail(queryFailed);

            function querySucceeded(data) {
                koCustomers([]);
                koCustomers(data.results);
            }
        }
// -- snip --

For reference here is my viewmdel as well

define(['durandal/app',
        'durandal/system',
        'durandal/plugins/router',
        'services/config',
        'services/logger',
        'services/datacontext'],
    function (app, system, router, config, logger, datacontext) {
        'use strict';
    var customers = ko.observableArray();

    var viewModel = {
        title: 'Vehicles',
        activate: activate,
        customers: customers
    };
    return viewModel;

    function activate() {
        return datacontext.getCustomers(customers);
    }
});

I am thinking I need some sort of mapping function that would accept observable and data.results and then loop through each result and expand it... Any example would be appreciated...

Upvotes: 1

Views: 334

Answers (2)

nikhil
nikhil

Reputation: 201

also push() can be used for extending observableArray

like this:

   function getCustomers(koCustomers) {
        var query = breeze.EntityQuery
            .from('Customers');

        return manager.executeQuery(query)
            .then(querySucceeded)
            .fail(queryFailed);

        function querySucceeded(data) {
            koCustomers([]);
            var temp =ko.observable();
var p =ko.observableArray();
p(data.results).
var len= p().length();
var i;

for(i=0; i<len; i++)
{
temp(p()[i].amount())
var q=ko.computed(function(){
return {amount: '$' + temp()} ;
koCustomer().push(q);
});
}
}
}

for date format use custom binding of dateString

link: http://www.aaronkjackson.com/2012/04/formatting-dates-with-knockoutjs/

hope it helped you

Upvotes: 0

Tomas Kirda
Tomas Kirda

Reputation: 8413

If it is just formatting then custom binding is simpler and more maintainable. If you need to extend the model, then when you get it from the server just apply transformations so that every entity has what you need. E.g.:

var entities = getEntitiesFromTheServer();

$.each(entities, function(i, entity){
    entity.formattedCurrency = ko.computed(function (){
        return '$' + entity.amount;
    });
});

This way you can bind it:

<span data-bind="text: formattedCurrency"></span>

Upvotes: 1

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