如何使用breeze.js为DateTimes设置自定义绑定？

Question

I'm trying to pull a DateTime object back from a database (using breeze), then trying to show a formatted date as a binding so that it can be edited and saved back to the DB. Problem is that somewhere along the line the Dates lose their "Entityness." I've tried using both custom bindings and computed observable examples from this site and others, to try to maintain all my Dates "Entityness," but nothing quite seems to work, either I can format the date OR save it.

Here's an example of a custom bind snippet I tried using:

    ko.bindingHandlers.datetimevalue = {
        init: function (element, valueAccessor, allBindingsAccessor) {
            // Use the value binding
            ko.bindingHandlers.value.init(element, valueAccessor, allBindingsAccessor);

            // Provide a custom text value
            var value = valueAccessor(), allBindings = allBindingsAccessor();
            var dateFormat = "DD/MM/YYYY h:mm a";
            var strDate = ko.utils.unwrapObservable(value);
            if (strDate) {
                var date = moment(strDate).format(dateFormat);
                $(element).val(date);
            }
            else {
                var date = moment(new Date()).format(dateFormat);
                $(element).val(date);
            }
        },
        update: function (element, valueAccessor, allBindingsAccessor) {
            // Use the value binding
            ko.bindingHandlers.value.update(element, valueAccessor, allBindingsAccessor);

            // Provide a custom text value
            var value = valueAccessor(), allBindings = allBindingsAccessor();
            var dateFormat = "DD/MM/YYYY h:mm a";
            var strDate = ko.utils.unwrapObservable(value);
            if (strDate) {
                var date = moment(strDate).format(dateFormat);
                $(element).val(date);
            }
        }
    };

In this example (taken from this link ) the date is displayed in the specified format, but is not persisted back to the server. How can I display a formatted date using breeze/moment and then save any changes made to this formatted date?

Thanks in advance,

Lowz

Answer 1

You don't have to use knockout custom binding; Breeze and moment together can do the job for you by extending the orders table to whatever you wish for.

You would've put some useful details in your question.. but I assume the idea is the same. Nevertheless, I'll take the example of the orders table.

Let's say you want to display the order date to the client in the format "DD/MM/YYYY h:mm a"

var manager = new breeze.EntityManager(remoteServiceName); // remoteServiceName is a string representing your controller path
 var Order = function() {
    this.formattedOrderDate = ko.computed(function () {
    var dt = this.orderDate();
    var value = (dt && moment.utc(dt).isValid()) ?
    moment.utc(dt).format('DD/MM/YYYY h:mm a') : '[Unknown]';
    return value;
    });
    }
manager.metadataStore.registerEntityTypeCtor('Orders',Order);

This will show the date in the desired format. For updating : set the orderDate() property to the computed value before calling saveChanges() :

order.setProperty("orderDate", new Date(order.formattedOrderDate()));
// Then....

manager.saveChanges();

This might be too late to answer your question, but I thought it might help