Unlocking the Power of Observable Objects with Knockout.js

Recently delving into knockoutjs, I came across the Microsoft tutorial showcasing how to integrate knockoutjs with MVC Web API. The tutorial can be found at: https://www.asp.net/web-api/overview/data/using-web-api-with-entity-framework/part-8. In a particular step of the tutorial, it explains the process of assigning a "Book" object to an observable and then binding its properties to html. For instance, accessing the AuthorName property like this:

data-bind="text: detail().AuthorName"

The observable structure and ajax call are as follows:

self.detail = ko.observable();

self.getBookDetail = function (item) {
    ajaxHelper(booksUri + item.Id, 'GET').done(function (data) {
        self.detail(data);
    });
}

function ajaxHelper(uri, method, data) {
    self.error(''); 
    return $.ajax({
        type: method,
        url: uri,
        dataType: 'json',
        contentType: 'application/json',
        data: data ? JSON.stringify(data) : null
    }).fail(function (jqXHR, textStatus, errorThrown) {
        self.error(errorThrown);
    });
}

A concern arises about accessing the AuthorName property from within javascript code. Attempting to access it using `self.detail().AuthorName` did not yield the expected result. Unsure if it's a syntax error or something more intricate.

self.detail().AuthorName

The complete source code for this sample project is available for download here: https://github.com/MikeWasson/BookService

Answer №1

Here are two code snippets with a sample user interface that aim to replicate your desired outcome. It seems like there may be an issue with how the view model is set up or with calling the getBookDetail method.

function ViewModel(){
    self = this;
  
    self.detail = ko.observable();

    self.getBookDetail = function () {
        var book = { AuthorName: 'foo', Category: 'bar'};
        self.detail(book);
    }
    
    self.getBookDetail();
}

ko.applyBindings(new ViewModel());
<script src="https://cdnjs.cloudflare.com/ajax/libs/knockout/3.2.0/knockout-min.js"></script>
<div data-bind="text:detail().AuthorName"></div>

function ViewModel(){
    self = this;
  
    self.detail = ko.observable();

    self.getBookDetail = function () {
        var book = { AuthorName: 'foo', Category: 'bar'};
        self.detail(book);
    }
   
}

ko.applyBindings(new ViewModel());
<script src="https://cdnjs.cloudflare.com/ajax/libs/knockout/3.2.0/knockout-min.js"></script>
<div data-bind="text:detail() !== undefined ? detail().AuthorName : '' "></div>
<input type="button" value="click" data-bind="click: getBookDetail"/>

Answer №2

Verify the presence of self.detail().AuthorName
. Ensure that self.detail() is not returning a value of null, or an object lacking the property AuthorName.

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