I have a data-object in my Javascript code described as follows:
//Data Object that represents products
function Product(n, p, t, d) {
this.name = ko.observable(n);
this.price = ko.observable(p);
tags = typeof (t) !== 'undefined' ? t : [];
this.tags = ko.observableArray(tags);
discount = typeof (d) !== 'undefined' ? d : 0;
this.discount = ko.observable(discount);
this.formattedDiscount = ko.computed(function ()
{ return (this.discount() * 100) + "%"; }
,this);
}
Then, I have an AJAX call to retrieve data in JSON format
$(document).ready(function () {
$.ajax({
type: "POST",
url: "ShoppingCartExampleExample.aspx/SendData",
data: "{}",
contentType: "application/json; charset=utf-8",
dataType: "json",
success: function (msg) {
alert(msg.d);
}
});
});
The AJAX call is working, I got this as result:
[
{"Discount":0,
"Name":"Chocolate",
"Price":"7.99"
"tags": ["Mars","Snickers"]
},
{"Discount":0.05,
"Name":"Beer",
"Price":"3.99"
"tags": ["Large","Extra"]
}
]
How could I map this list of objects received from an AJAX call to my Data-object?
I would like to map this list to an observable array and also map the tags array to an observable array, because I have a foreach binding that fills an HTML table to present the products and tags.
Thank You
Knockout utility functions are now included in the latest builds and are my preferred way of handling things. The mapping plugin is really overused at times and can make your objects more bloated than they need to be if not used correctly.
When your array of objects are returned, use the utility class:
var newProducts = ko.utils.arrayMap(data, function(dataItem) {
return new Product(...);
});
ko.utils.arrayPushAll(myViewModel.products, newProducts);
Pretty straight forward and supported. You could even put the arrayMap directly into the arrayPushAll as the second parameter and skip declaring the newProducts variable.
So assuming in your success function msg.d is your array. Just loop through the array and for each item call new Product for each item and then push the result into the observable array of whatever you parent view model is. For example, if you have something like:
var rootViewModel = function() {
this.products = ko.observableArray();
//... whatever other properties and functions you have
}
var myViewModel = new rootViewModel();
Then in your success function of your ajax call, you'd do something like:
success: function (msg) {
msg.d.forEach(function(item) {
myViewModel.products.push(new Product(item.Name, item.Price, item.tags. item.Discount));
}
}
Some of this plumbing can be avoided by using the mapping plugin which is pretty configurable to allow you to map your plain javascript objects from your ajax call to whatever view model you want.
Related
I have a problem creating observable array of observables. I search on google but didn't find a solution. It may be something simple that I can't notice, because I'm new to Knockout.
But I have the model:
eventsModel = function () {
var self = this;
self.endTimeInMinutes = ko.observable();
self.events = ko.observableArray([]);
self.startTripTime = ko.observable();
self.endTripTime = ko.observable();
}
and I want to have an observables items in my array so I write a ViewModel and bind the model.
eventItemViewModel = function(o) {
var self = this;
self.BeginInMinutes = ko.observable(o.BeginInMinutes);
self.Type = ko.observable(o.Type);
};
var events = new eventsModel();
ko.applyBindings(events);
And I'm fetching the data using AJAX:
function GetEvents() {
$.ajax({
url: "Contact.aspx/GetEvents",
async: true,
type: "POST",
contentType: "application/json",
dataType: "json",
success: function (data) {
var temp = data.d;
endTimeInMinutes = temp["EndInMinutes"];
eventsArr = temp["Events"];
eventsArray = JSON.parse(JSON.stringify(eventsArr));
events.events(eventsArray);
},
});
}
After this I have an observable array but without observables values inside. Now I trying to add in my AJAX method:
events.events(ko.utils.arrayMap(eventsArray, function(eve) {return new eventItemViewModel(eve); }));
But if I do console.log on this, then I am getting array of objects, and in each object there is a BeginInMinutes and Type, but it's value is like function d()... etc.
I'm really get stucked with it, and I believe I made some very simple mistake somewhere.
Thanks for helping me.
You already got an observableArray with observable element inside it,Your problem really is with getting those values
use this code to get the real value of the first element in the array.
console.log(events.events()[0].BeginInMinutes());
I'm having problems with passing two arrays of strings as arguments in JSON format to invoke ASMX Web Service method via jQuery's "POST".
My Web Method is:
[ScriptMethod(ResponseFormat=ResponseFormat.Json)]
public List<string> CreateCollection(string[] names, string[] lastnames)
{
this.collection = new List<string>();
for (int i = 0; i < names.Length; i++)
{
this.collection.Add(names[i] + " " + lastnames[i]);
}
return this.collection;
}
Now, the js:
function CreateArray() {
var dataS = GetJSONData(); //data in JSON format (I believe)
$.ajax({
type: "POST",
url: "http://localhost:45250/ServiceJava.asmx/CreateCollection",
data: dataS,
contentType: "application/json; charset=utf-8",
dataType: "json",
success: function (data) {
//something
}
})
}
GetJSONData() is my helper method creating two arrays from column in a table. Here's the code:
function GetJSONData() {
//take names
var firstnames = $('#data_table td:nth-child(1)').map(function () {
return $(this).text();
}).get(); //["One","Two","Three"]
//take surnames
var surnames = $('#data_table td:nth-child(2)').map(function () {
return $(this).text();
}).get(); //["Surname1","Surname2","Surname3"]
//create JSON data
var dataToSend = {
names: JSON.stringify(firstnames),
lastnames: JSON.stringify(surnames)
};
return dataToSend;
}
Now, when I try to execude the code by clicking button that invokes CreateArray() I get the error:
ExceptionType: "System.ArgumentException" Message: "Incorrect first
JSON element: names."
I don't know, why is it incorrect? I've ready many posts about it and I don't know why it doesn't work, what's wrong with that dataS?
EDIT:
Here's dataToSend from debugger for
var dataToSend = {
names: firstnames,
lastnames: surnames,
};
as it's been suggested for me to do.
EDIT2:
There's something with those "" and '' as #Vijay Dev mentioned, because when I've tried to pass data as data: "{names:['Jan','Arek'],lastnames:['Karol','Basia']}", it worked.
So, stringify() is not the best choice here, is there any other method that could help me to do it fast?
Try sending like this:
function CreateArray() {
var dataS = GetJSONData(); //data in JSON format (I believe)
$.ajax({
type: "POST",
url: "http://localhost:45250/ServiceJava.asmx/CreateCollection",
data: {names: dataS.firstnames,lastnames: dataS.surnames} ,
contentType: "application/json; charset=utf-8",
dataType: "json",
success: function (data) {
//something
}
})
}
This should work..
I think since you are already JSON.stringifying values for dataToSend property, jQuery might be trying to sending it as serialize data. Trying removing JSON.stringify from here:
//create JSON data
var dataToSend = {
names : firstnames,
lastnames : surnames
};
jQuery will stringify the data when this is set dataType: "json".
Good luck, have fun!
Altough, none of the answer was correct, it led me to find the correct way to do this. To make it work, I've made the following change:
//create JSON data
var dataToSend = JSON.stringify({ "names": firstnames, "lastnames": surnames });
So this is the idea proposed by #Oluwafemi, yet he suggested making Users class. Unfortunately, after that, the app wouldn't work in a way it was presented. So I guess if I wanted to pass a custom object I would need to pass it in a different way.
EDIT:
I haven't tried it yet, but I think that if I wanted to pass a custom object like this suggested by #Oluwafemi, I would need to write in a script:
var user1 = {
name: "One",
lastname:"OneOne"
}
and later pass the data as:
data = JSON.stringify({ user: user1 });
and for an array of custom object, by analogy:
data = JSON.stringify({ user: [user1, user2] });
I'll check that one later when I will have an opportunity to.
I know how to pass some parameters to a JQuery $.getJSON callback method, thanks to this question:
$.getJSON('/website/json',
{
action: "read",
record: "1"
},
function(data) {
// do something
});
And I can also submit a form to a $.getJSON callback method:
$.getJSON('/website/json', $(formName)
function(data) {
// do something
});
But I want to pass some parameters AND submit some form elements. How can I combine the two things togheter?
I could serialize the form elements and manually add some parameters to the url, and it looks like it works:
$.getJSON('/website/json',
'action=read&record=1&'
+ $(formName).serialize(),
function(data) {
// do something
});
But it doesn't look very elegant. Is this the proper way, or there's a better way to do it?
We could implement the functionality demonstrated in this answer as a custom jQuery instance method which produces an object of key/value pairs from a form and combines it with the properties that aren't derived from the form:
$.fn.formObject = function (obj) {
obj = obj || {};
$.each(this.serializeArray(), function (_, kv) {
obj[kv.name] = kv.value;
});
return obj;
};
$.getJSON('/website/json', $(formName).formObject({
action: "read",
record: "1"
}), function(data) {
// do something
});
Make an Ajax post to send the data to the server. Retrieve the parameter data in the backend code along with the form data.
var formData = {data from form};
formData.action = 'read';
formData.post = '1';
$.ajax({
url: '/website/json',
type: "post",
data: formData
}).done(function (data) {
// remove prior values set upon request response
formData.action = null;
formData.post = null;
});
I have getGeneral function that calls ajax GET. When ajax recieves data (json), it creates KO model from given json and returns created KO.
When Knockout model is created and values are assigned, knockout applybindings should be called. Here is my code:
Defines GeneralModel and some related functions (inside "GeneralModel.js"):
var GeneralModel = function() {
//for now it is empty as data ar binded automatically from json
// CountryName is one of the properties that is returned with json
}
function getGeneral(pid) {
$.ajax({
url: "/api/general",
contentType: "text/json",
dataType: "json",
type: "GET",
data: { id: pid},
success: function (item) {
var p = new GeneralModel();
p = ko.mapping.fromJS(item);
return p;
},
error: function (data) {
}
});
}
This is called from another file (GeneralTabl.html), it should call get function and applyBindings to update UI:
var PortfolioGeneral = getGeneral("#Model.Id");
ko.applyBindings(PortfolioGeneral, document.getElementById("pv-portfolio-general-tab"));
However, in this scenario I am getting error (CountryName is not defined). This is because applyBindings happens before ajax returns data, so I am doing applyBindings to empty model with undefined properties.
Mapping from Json to Model happens here and is assignes values:
p = ko.mapping.fromJS(item);
I can also fill in GeneralModel with all fields, but it is not necessary (I guess):
var GeneralModel = function() {
CountryName = ko.observable();
...
}
It will still give an error "CountryName is not defined".
What is the solution?
1) Can I somehow move getGeneral inside GeneralModel, so get data would be part of GeneralModel initialization?
or
2) Maybe I should somehow do "wait for ajax results" and only then applyBindings?
or
I believe there are other options, I am just not so familiar with KO and pure JS.
Note: I fully understand that this is because Ajax is Async call, so the question is how to restructure this code taking into account that I have two seperate files and I need to call getGeneral from outside and it should return some variable.
Try using the returned promise interface:
function getGeneral(pid) {
return $.ajax({
url: "/api/general",
contentType: "text/json",
dataType: "json",
type: "GET",
data: {
id: pid
}
});
}
getGeneral("#Model.Id").done(function (item) {
var p = new GeneralModel();
p = ko.mapping.fromJS(item);
ko.applyBindings(p, document.getElementById("pv-portfolio-general-tab"));
}).fail(function () {
//handle error here
});
Im trying to develop a class in JavaScript I can use to access a load of data that is gathered by an AJAX request easily. The only problem is I need to make the members of the class accessible only once the AJAX call is complete. Ideally what I would like to end up is something where by I can call this in a script:
courses.getCourse('xyz').complete = function () {
// do something with the code
}
And this will only fire after the AJAX call has been complete and the data structures in the "class" are ready to be used. Ideally I dont want to have to create a .complete member for every function in the class
Here is the "class" I am trying to make so far:
var model_courses = (function() {
var cls = function () {
var _storage = {}; // Used for storing course related info
_storage.courses = {}; // Used for accessing courses directly
_storage.references = new Array(); // Stores all available course IDs
var _ready = 0;
$.ajax({
type: "GET",
url: "data/courses.xml",
dataType: "xml",
success: function(xml) {
$(xml).find("course").each(function() {
_storage.courses[$(this).attr('id')] = {
title : $(this).find('title').text(),
description : $(this).find('description').text(),
points : $(this).find('points').text()
}
_storage.references.push($(this).attr('id'))
})
}
})
console.log(_storage.courses)
}
cls.prototype = {
getCourse: function (courseID) {
console.log(cls._storage)
},
getCourses: function () {
return _storage.courses
},
getReferences: function (),
return _storage.references
}
}
return cls
})()
At the moment getCourse will be fired before the AJAX request is complete and obviously it will have no data to access.
Any ideas will be greatly appreciated, im stuck on this one!
jQuery already handles this for you using deferred objects, unless i'm misunderstanding what you are looking for.
var courses = {
getCourse: function (id) {
return $.ajax({url:"getCourse.php",data:{id:id});
}
};
courses.getCourse("history").done(function(data){
console.log(data);
});
I know this isn't exactly what you are looking for, I'm hoping it's enough to push you in the right direction. Deferred objects are awesome.
The following changes allow you to make the AJAX request just once and you can call your function like
courses.getCourse('xyz', function(course){
// Use course here
});
Here are the changes
var model_courses = (function() {
// This is what gets returned by the $.ajax call
var xhr;
var _storage = {}; // Used for storing course related info
_storage.courses = {}; // Used for accessing courses directly
_storage.references = []; // Stores all available course IDs
var cls = function () {
xhr = $.ajax({
type: "GET",
url: "data/courses.xml",
dataType: "xml",
success: function(xml) {
$(xml).find("course").each(function() {
_storage.courses[$(this).attr('id')] = {
title : $(this).find('title').text(),
description : $(this).find('description').text(),
points : $(this).find('points').text()
}
_storage.references.push($(this).attr('id'))
});
}
});
}
cls.prototype = {
// Made changes here, you'd have to make the same
// changes to getCourses and getReferences
getCourse: function (courseID, callback) {
if (xhr.readyState == 4) {
callback(_storage.courses[courseID]);
}
else {
xhr.done(function(){
callback(_storage.courses[courseID]);
})
}
},
getCourses: function () {
return _storage.courses
},
getReferences: function (),
return _storage.references
}
}
return cls
})()
As a side note, your module pattern will not work very well if you need to instantiate two of these model_courses objects, since the storage objects are all shared in your self calling function's closure. You usually don't mix the module pattern with prototypes (returning a constructor from a module), unless you really know what you are doing, that is, the shared closure variables work as static properties of your class.
This is what I would do if I were you (since you really want private variables)
function ModelCourses() {
var storage = {
courses: {},
references: []
};
var xhr = $.ajax({
type: "GET",
url: "data/courses.xml",
dataType: "xml",
success: function(xml) {
$(xml).find("course").each(function() {
storage.courses[$(this).attr('id')] = {
title : $(this).find('title').text(),
description : $(this).find('description').text(),
points : $(this).find('points').text()
}
storage.references.push($(this).attr('id'))
})
}
});
this.getCourse = function(courseId, callback) {
function getCourse() {
callback(storage.courses[courseID])
}
if (xhr.readyState == 4) {
getCourse();
}
else {
xhr.done(getCourse);
}
};
}
in getStorage either add a check to see if there is any data to pilfer (preferred), or make the "actual" method private than publicize it when it has items it can access. (I would recommend the first though otherwise you'll get exceptions about calling a method that doesn't exists on an object).
You can define a function getData that would perform the ajax request and that would take the getCourse as a callback.
The getData could possibly store locally the result of the Ajax call and test the local storage before performing the ajax call.
You could also specify a private member to allow the ajax call to be run only once.
You might want to check underscore.js for some handy tool
Here is a short example code :
cls.prototype.getData = function(callback) {
/*perform ajax call or retrieve data from cache*/
callback()
}
cls.prototype.getCourse = function(id) {
this.getData(function() {
/*do something with the data and the id you passed*/
}
}