I use knockout to build a Visualization Application, which could bind to Values. Problem is, sometimes I bind to a Path ("aa.bb.cc.dd") where a child could be undefined (cc = undefined). Then, no binding should happen, it should be ignored!
This could work if I nest this in several div's and use with binding, but all of this is done in code behind, and I would not like the Idea of having so many nested divs! Is there another solution?
I can think of three options:
(1) Handle the nullable fields via nested bindings (as mentioned)
<!-- ko if: aa() -->
<!-- ko if: aa().bb() -->
<!-- ko if: aa().bb().cc() -->
<input data-bind="value: aa().bb().cc().dd"></input>
<!-- /ko -->
<!-- /ko -->
<!-- /ko -->
(2) Build a computable that traverses the tree and returns null if needed
thing.bindableDD = ko.pureComputed(function () {
if (thing.aa()) {
if (thing.aa().bb()) {
if (thing.aa().bb().cc()) {
return thing.aa().bb().cc().dd;
} else return null;
} else return null;
} else return null;
};
<input data-bind="value: bindableDD"></input>
(3) Create a custom binding that checks for undefined values.
I've never created a custom binding handler so maybe someone else could assist with the format but I think it'd have this in it:
try {
value(); // try to access it
} catch (e) {
return null;
}
<input data-bind="nullableValue: thing.aa().bb().cc().dd"></input>
You can use the eval function to traverse through the path. If this path does not exist, simply return null and knockout will not render the element.
Something like this:
<div data-bind="text: traverse('this.a1().b().c().d')"/>
<div data-bind="text: traverse('this.a2().b().c().d')"/>
<script>
var ViewModel = function() {
this.a1 = ko.observable({b: ko.observable({c: ko.observable({ d: 'd value' })})});
this.a2 = ko.observable({b: ko.observable()});
this.traverse = function(path) {
try {
return eval(path);
} catch(err) {
return null;
}
}
}
</script>
I've now solved it by changing in knockout.js line 2597 from:
val = 'function(){return ' + val + ' }';
to:
val = 'function(){try{return ' + val + ' }catch(e){console.warn(\''+val.replace(/'/g,"\"")+' - undefined property in path\');}}';
Related
I have two input box in angularjs html structure.
When I click on my button or a tag I want my textbox old and new value in angularjs or I want to compare that old and new value are same or not.
I'm using angular 1.4.7.
<input phone-input ng-show="mode == 'edit'" ng-model="leader.work"/>
<input phone-input ng-show="mode == 'edit'" ng-model="leader.mobile"/>
<a ng-show="mode == 'edit'" ng-click="mode = null;save_profile(leader)" style="cursor: pointer" title="Save">Save</a>
$scope.save_profile = function (leader) {
/* How to get/compare both text box old and new value are same or not*/
};
try this
function TodoCrtl($scope) {
$scope.newValue = 'Initial Text';
$scope.save_profile = function(newvalue, oldvalue) {
//Here you can access old value and new value from scope.
$scope.new = 'New Value :' + $scope.newValue;
$scope.old = 'Old Value :' + $scope.oldValue;
//After accessing update the scope old value to new value with function parameters
$scope.newValue = newvalue;
$scope.oldValue = newvalue;
};
$scope.changeValue = function() {
$scope.newValue = 'Dynamic Change';
};
}
<!DOCTYPE html>
<html ng-app>
<head>
<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.1.5/angular.min.js"></script>
<meta charset=utf-8 />
<title>ng-click</title>
</head>
<body>
<div ng-controller="TodoCrtl">
<input type=text ng-model="newValue" ng-init="oldValue=newValue">
<button ng-click="save_profile(newValue,oldValue)">Save</button>
<div>{{new}}</div>
<div>{{old}}</div>
<br>
<button ng-click="changeValue()">Change Dynamic</button>
</div>
</body>
</html>
The simplest possible approach which will work in all occasions is to make a copy of the leader when you load it and compare current leader with the copy you made when you press the button.
function TodoCtrl($scope) {
// initialization
var originalLeader = null;
$scope.leader = null;
$scope.mode = 'edit';
// this is where you get your leader data, in my example
// I simply set it to demo data but you can load the
// data using AJAX for example
var loadLeader = function() {
var leaderData = {
mobile: '000',
work: '111'
};
originalLeader = angular.copy(leaderData);
$scope.leader = leaderData;
}
// loadLeader will be invoked on page load
loadLeader();
$scope.save_profile = function (leader) {
// you have access to your original data and current data,
// you can compare them and do whatever you want with them
console.log('originalLeader ', originalLeader);
console.log('leader ', leader);
// for example
if ( leader.mobile != originalLeader.mobile ) {
alert('Mobile has changed from ' + originalLeader.mobile + ' to ' + leader.mobile);
}
};
}
Some answers suggested to use $scope.$watch, you can implement your solution using that but you need to be careful as the $scope.$watch callback will be invoked on each change. To illustrate what I mean let's add something like this to your code:
$scope.$watch('leader.mobile', function(newVal,oldVal) {
console.log('newVal ', newVal);
console.log('oldVal ', oldVal);
});
Let the leader.mobile be 000 at the init time.
You type 1 to the text box, now leader.mobile is 0001, the callback function will be invoked and the log will be:
newVal 0001
oldVal 000
Now you press backspace and delete 1 you previously typed, the leader.mobile variable is now 000 and the log is:
newVal 000
oldVal 0001
Your current data is same as starting data but the $scope.$watch was invoked twice and is difficult to determine if data has really changed or not. You would need to implement some additional code for that, something like this:
// be careful about this, you need to set to null if you reload the data
var originalMobile = null;
$scope.$watch('leader.mobile', function(newVal,oldVal) {
// set originalMobile to value only if this is first
// invocation of the watch callback, ie. if originalMobile
// was not set yet
if ( originalMobile == null ) {
originalMobile = oldVal;
}
});
$scope.save_profile = function(leader) {
if ( leader.mobile != originalMobile ) {
// ...
}
}
You can use the $watch function. The link below will show you how to implement it. You can get an old and new value with it.
How do I use $scope.$watch and $scope.$apply in AngularJS?
I've got an issue where my viewmodel has an observable object that contains observable properties. When I try to access those properties they don't display. I can, however, see that all the properties with values are visible in the DOM using the Knockout chrome extension.
My code looks like:
viewmodel:
self.device=ko.observable();
self.device(querydevice.query({"url": self.url, "ref":self.ref}));
query code:
define(['jquery','knockout','hsd'], function ($,ko, device) {
return{
query:function (params) {
var hsdevice=ko.observable();
self.url=params.url;
self.ref=params.ref;
var controlData = $.getJSON(self.url + "/JSON?request=getcontrol&ref=" + self.ref);
var statusData = $.getJSON(self.url + "/JSON?request=getstatus&ref=" + self.ref);
$.when(controlData, statusData).done(function (_cdata, _sdata) {
var data = $.extend(_cdata[0], _sdata[0]);
hsdevice(new device(data));
});
return hsdevice;
}};
});
device object:
define(['knockout'], function (ko) {
return function device (data){
var self=this;
self.deviceName = ko.observable(data.Devices[0].name);
self.value = ko.observable(data.Devices[0].value);
self.status =ko.observable(data.Devices[0].status);
self.controlPairs = ko.observableArray();
ko.utils.arrayPushAll(self.controlPairs, data.ControlPairs);
};
});
This is what I see being returned:
" device": Object
controlPairs: Array[2]
deviceName: "Garage Hall Light"
status: "Off"
value: 0
In my HTML I have this:
<span class="tile-title align-" data-bind="with: device.deviceName"></span>
I've also tried using data-bind:"text: device().deviceName", but that doesn't work either. Nothing displays. I can however access over observable properties that are on the viewmodel. The only difference is that they're single level properties with no sub-binding. So I am able to see something like self.test("test") in my html but not my self.device with the nested databinds.
Any ideas what I'm doing wrong?
Thanks!
It looks like you are using jquery promises. what you need to do is return the $.when
something like
define(['jquery','knockout','hsd'], function ($,ko, device) {
return{
query:function (params) {
self.url=params.url;
self.ref=params.ref;
var controlData = $.getJSON(self.url + "/JSON?request=getcontrol&ref=" + self.ref);
var statusData = $.getJSON(self.url + "/JSON?request=getstatus&ref=" + self.ref);
return $.when(controlData, statusData).done(function (_cdata, _sdata) {
var data = $.extend(_cdata[0], _sdata[0]);
return new device(data);
});
}};
});
then you end up with something like this.
querydevice.query({"url": self.url, "ref":self.ref})
.when(function(data){
self.device(data);
return true;
});
Thanks to Nathan for his code contribution. I was finally able to access my nested properties in the html by using:
<!-- ko with: device -->
<!-- /ko -->
and THEN data-bind to the property I needed.
I am new to Knockout and have been trying to follow code examples and the documentation, but keep running into an issue. My data bindings printing the Knockout observable function, not the actual values held by my observable fields. I can get the value if I evaluate the field using (), but if you do this you do not get any live data-binding / updates.
Below are some code snippets from my project that are directly related to the issue I am describing:
HTML
<div class="col-xs-6">
<div data-bind="foreach: leftColSocialAPIs">
<div class="social-metric">
<img data-bind="attr: { src: iconPath }" />
<strong data-bind="text: name"></strong>:
<span data-bind="text: totalCount"></span>
</div>
</div>
</div>
Note: leftColSocialAPIs contains an array of SocialAPIs. I can show that code too if needed.
Initializing the totalcount attribute
var SocialAPI = (function (_super) {
__extends(SocialAPI, _super);
function SocialAPI(json) {
_super.call(this, json);
this.totalCount = ko.observable(0);
this.templateName = "social-template";
}
SocialAPI.prototype.querySuccess = function () {
this.isLoaded(true);
appManager.increaseBadgeCount(this.totalCount());
ga('send', 'event', 'API Load', 'API Load - ' + this.name, appManager.getRedactedURL());
};
SocialAPI.prototype.toJSON = function () {
var self = this;
return {
name: self.name,
isActive: self.isActive(),
type: "social"
};
};
return SocialAPI;
})(API);
Updating totalcount attribute for LinkedIn
var LinkedIn = (function (_super) {
__extends(LinkedIn, _super);
function LinkedIn(json) {
json.name = "LinkedIn";
json.iconPath = "/images/icons/linkedin-16x16.png";
_super.call(this, json);
}
LinkedIn.prototype.queryData = function () {
this.isLoaded(false);
this.totalCount(0);
$.get("http://www.linkedin.com/countserv/count/share", { "url": appManager.getURL(), "format": "json" }, this.queryCallback.bind(this), "json").fail(this.queryFail.bind(this));
};
LinkedIn.prototype.queryCallback = function (results) {
if (results != undefined) {
results.count = parseInt(results.count);
this.totalCount(isNaN(results.count) ? 0 : results.count);
}
this.querySuccess();
};
return LinkedIn;
})(SocialAPI);
In the <span data-bind="text: totalCount"></span>, I expect to see a number ranging from 0-Integer.MAX. Instead I see the following:
As you can see, its outputting the knockout function itself, not the value of the function. Every code example I've seen, including those in the official documentation, says that I should be seeing the value, not the function. What am I doing wrong here? I can provide the full application code if needed.
Not sure, but KO view models obviously tend to bind own (not inherited through prototypes) observable properties only. So you should rewrite your code to supply totalCount observable for every social network separately.
I'm trying to see if angularJs is useful for me to create a team-management application.
The issue I have:
I have a complex ng-class definition, being
ng-class="{'guard': ( guard.checked && day.func.indexOf('guard') != -1) }"
and it will prove to be bigger yet.
I was wondering if there is a way to have basically this:
# pseudocode, needs to be translated to js/angularJs
function getClasses(){
classes = ''
if ('guard' in user.day.func and guardCheckBox == checked){
classes = classes.append(' guard')
}
if ('f2' in user.day.func and f2CheckBox == checked){
classes = classes.append(' f2')
}
....
if ('fx' in user.day.func and fxCheckBox == checked){
classes = classes.append(' fx')
}
return(stripLeadingSpace(classes)
}
any tips on what to search, or any bits of code would be appreciated
a js-fiddle with what I have as of yet can be found here:
http://jsfiddle.net/mTJDh/1/
code from the fiddle for dead links
HTML:
Guard
<!--
this snippet applies the class 'guard' to every cell when the checkbox 'Guard' is checked
-->
<div ng-controller="MyCtrl">
<table ng-repeat="user in users">
<tr>
<td>{{user.name}}</td>
<td ng-repeat="day in user.days" ng-class="{'guard': ( guard.checked && day.func.indexOf('guard') != -1) }">
{{day.number}}
</td>
</tr>
</table>
</div>
JS
var myApp = angular.module('myApp', []);
function MyCtrl($scope) {
$scope.users = [
{name: 'PEDC',
days : [{number:'1', func:'guard'},
{number:'2', func:'guard'},
{number:'3', func:'guard'},
{number:'4', func:['guard','spoc']}
]
},
{name: 'JOVH',
days : [{number:'1', func:'guard'},
{number:'2', func:'guard'},
{number:'3', func:'spoc'},
{number:'4', func:'guard'}
]
}
];
}
CSS
.pending-delete {
background-color: pink
}
.guard {
border:solid black 1px
}
.spoc {
background-color: pink
}
EDIT:
This is the actual solution I use now:
http://jsfiddle.net/mTJDh/2/
basically:
added functions isGuard, isSpoc and isHoliday to my controller, with the day as an argument
these return true or false based on the json array.
idea gotten from here and https://docs.angularjs.org/api/ng/input/input%5Bcheckbox%5D
ngClass also accepts methods defined on scope which return a boolean value. So you can do something like this:
<td ng-repeat="day in user.days" ng-class="{ 'guard' : getClass(day) }">
{{day.number}}
</td>
JS
$scope.getClass = function(day){
return $scope.guard.checked && day.func.indexOf('guard') != -1
}
I updated your fiddle:
http://jsfiddle.net/mTJDh/4/
use the ngClass as in the accepted answer:
<td ng-repeat="day in user.days" ng-class="getClasses(day)" day="day">
{{day.number}}
</td>
but this time rewrite the method getClasses to return an array.
the array contains at the end every class you wants for a specific day.
$scope.getClasses = function(day){
var classes = [];
if($scope.spoc && $scope.isSpoc(day)) classes.push("spoc");
if($scope.guard && $scope.isGuard(day)) classes.push("guard");
if($scope.holiday && $scope.isHoliday(day)) classes.push("holiday");
return classes;
}
and if you want a more generic one:
http://jsfiddle.net/mTJDh/5/
define:
var availableClasses = [
"guard",
"spoc",
"holiday"]
and use a loop:
$scope.getClasses = function (day) {
var classes = [];
angular.forEach(availableClasses, function (value) {
if ($scope[value] && day.func.indexOf(value) != -1) classes.push(value);
});
return classes;
}
I would use a directive, it was a bit hard to tell from your example which scope variables your CSS rules rely on (and what exactly the rules are), but hopefully it's enough to get started.
.directive('guardClass', [function() {
return {
restrict: 'A',
scope: {
guard: '=',
user: '='
},
link: function(scope, element, attrs, controller) {
scope.$watch(function() {
//return enough info about scope.guard and scope.user
//to know when one has changed
return ...
}, function() {
var classes = [];
if (...) {
classes.push('guard');
}
if (...) {
classes.push('f2');
}
....
if (...) {
classes.push('fx');
}
element.attr('class', classes.join(' '));
});
}
};
}])
And then in HTML
<td guard-class guard="guard" user="user" />
You feed the directive the two (or more) objects it needs to calculate the CSS classes. The directive sets up a $watch to trigger whenever whatever properties on those objects change. It then finds all CSS classes that needs to be there and puts them on the element using angular element.
This saves you from cluttering up your controller with this logic, and it saves you from having extensive amounts of logic inside your templates.
I am trying to filter my users observableArray which has a nested keywords observableArray
based on a keywords observableArray on my viewModel.
When I try to use ko.utils.arrayForEach I get a stack overflow exception. See the code below, also posted in this jsfiddle
function User(id, name, keywords){
return {
id: ko.observable(id),
name: ko.observable(name),
keywords: ko.observableArray(keywords),
isVisible: ko.dependentObservable(function(){
var visible = false;
if (viewModel.selectedKeyword() || viewModel.keywordIsDirty()) {
ko.utils.arrayForEach(keywords, function(keyword) {
if (keyword === viewModel.selectedKeyword()){
visible = true;
}
});
if (!visible) {
viewModel.users.remove(this);
}
}
return visible;
})
}
};
function Keyword(count, word){
return{
count: ko.observable(count),
word: ko.observable(word)
}
};
var viewModel = {
users: ko.observableArray([]),
keywords: ko.observableArray([]),
selectedKeyword: ko.observable(),
keywordIsDirty: ko.observable(false)
}
viewModel.selectedKeyword.subscribe(function () {
if (!viewModel.keywordIsDirty()) {
viewModel.keywordIsDirty(true);
}
});
ko.applyBindings(viewModel);
for (var i = 0; i < 500; i++) {
viewModel.users.push(
new User(i, "Man " + i, ["Beer", "Women", "Food"])
)
}
viewModel.keywords.push(new Keyword(1, "Beer"));
viewModel.keywords.push(new Keyword(2, "Women"));
viewModel.keywords.push(new Keyword(3, "Food"));
viewModel.keywords.push(new Keyword(4, "Cooking"));
And the View code:
<ul data-bind="template: { name: 'keyword-template', foreach: keywords }"></ul><br />
<ul data-bind="template: { name: 'user-template', foreach: users }"></ul>
<script id="keyword-template" type="text/html">
<li>
<label><input type="radio" value="${word}" name="keywordgroup" data-bind="checked: viewModel.selectedKeyword" /> ${ word }<label>
</li>
</script>
<script id="user-template" type="text/html">
<li>
<span data-bind="visible: isVisible">${ $data.name }</span>
</li>
</script>
Your isVisible dependentObservable has created a dependency on itself and is recursively trying to evaluate itself based on this line:
if (!visible) {
viewModel.users.remove(this);
}
So, this creates a dependency on viewModel.users, because remove has to access the observableArray's underlying array to remove the user. At the point that the array is modified, subscribers are notified and one of the subscribers will be itself.
It is generally best to not change the state of any observables in a dependentObservable. you can manually subscribe to changes to a dependentObservable and makes your changes there (provided the dependentObservable does not depend on what you are changing).
However, in this case, I would probably instead create a dependentObservable at the viewModel level called something like filteredUsers. Then, return a version of the users array that is filtered.
It might look like this:
viewModel.filteredUsers = ko.dependentObservable(function() {
var selected = viewModel.selectedKeyword();
//if nothing is selected, then return an empty array
return !selected ? [] : ko.utils.arrayFilter(this.users(), function(user) {
//otherwise, filter on keywords. Stop on first match.
return ko.utils.arrayFirst(user.keywords(), function(keyword) {
return keyword === selected;
}) != null; //doesn't have to be a boolean, but just trying to be clear in sample
});
}, viewModel);
You also should not need the dirty flag, as dependentObservables will be re-triggered when any observables that they access have changed. So, since it accesses selectedKeyword, it will get re-evaluated whenever selectedKeyword changes.
http://jsfiddle.net/rniemeyer/mD8SK/
I hope that I properly understood your scenario.