Develop Reference

Angular change default value of select from filter

I have a select box which is populated with some data from my controller. When an input value changes the contents of the select box should be filtered and a default value should be assigned based on the is default property of the data object.
Is there any way this can be done using angular directives or would it need to be done as a custom filter function doing something along the lines of
angular.forEach(vm.data,function(item){
if (vm.q == item.someId && item.isDefault) {
vm.result = item.value;
}
});
My html looks something like
<div ng-app="myApp" ng-controller="ctrl as vm">
<input type="text" ng-model="vm.q">
<select ng-options="item.value as item.description for item in vm.data | filter:{someId:vm.q}" ng-model="vm.result"></select>
</div>
and my controller looks like:
(function(){
angular.module('myApp',[]);
angular
.module('myApp')
.controller('ctrl',ctrl);
function ctrl()
{
var vm = this;
vm.data = [
{
someId: '1',
description: 'test1',
value: 100,
isDefault: true
},
{
someId: '2',
description: 'test2',
value: 200,
isDefault: false
},
{
someId: '3',
description: 'test3',
value: 100,
isDefault: true
},
];
}
})();
See my plunkr demo here: http://plnkr.co/edit/RDhQWQcHFMQJvwOyHI4r?p=preview
Desired behaviour:
1) Enter 1 into text box
2) List should be filtered to 2 items
3) Select box should pre-select item 1 based on property isDefault set to true
Thanks in advance

I'd suggest you include some 3rd party library, like lodash, into your project to make working with arrays/collections that much easier.
After that you could add ng-change directive for your input.
<input type="text" ng-model="vm.q" ng-change="vm.onChange(vm.q)">
And the actual onChange function in the controller
vm.onChange = function(id) {
var item = _.findWhere(vm.data, { someId: id, isDefault: true });
vm.result = item ? item.value : null;
};
And there you have it.

knockout.js dependent variable selects

[ Please see updates at the bottom ]
I'm trying to make knockout depended selects, it's intended to make a "product" selection by these attributes, for example a product can have "size" and "material", if I selected "size", a knockout script make a request to the backend and retrieves which "material" available for the selected size, in other words, if an attribute is selected, other attributes are filtered out to show only available values ("all sizes": 1,2,3,4,5; "aluminium": 1,4).
Attributes list are completely dynamic, there are about 80 attributes which can be linked to the products in arbitrary way.
Are there any "best practices" for this situation?
I am trying to solve it with code like this, without success yet:
var ViewModel = function(data) {
var self = this;
self.data = data;
self.attributes = ko.observableArray();
self.data.forEach(function(item, i, a) {
// I passed .self to catch it later
// in products as view_model.attributes().
self.attributes.push(new VariableProduct(item, self));
})
};
var VariableProduct = function(item, view_model) {
var self = this;
self.attribute_name = ko.observable(item.name);
self.attribute_value = ko.observable('--');
// list of attribute values
self.attribute_values = ko.computed(function() {
var result = {};
view_model.attributes().forEach(function(attribute, i, a) {
// here I try to filter each attributes lists by values
// it doesn't work well
if (attribute.attribute_name() != self.attribute_name() && self.attribute_value() != '--') {
result = attribute.attribute_values().filter(
function(value) {
return value.indexOf(self.attribute_value()) >= 0;
});
}
});
return result;
});
};
UPDATE 1:
With Dnyanesh's reference to ko.subscribe(), i've achived these results, isn't ok yet, but a progress:
http://jsfiddle.net/xwild/65eq14p3/
UPDATE 2:
At the end it was solved with knockout.reactor and knockout.mapping plugins.
Related stackoverflow question with details and the answer.

For dependent select I think you can use subscribe in following manner
var vm = {
sizes: ko.observableArray([
{ name: 'size 1', id: 1},
{ name: 'size 2', id: 2},
{ name: 'size 3', id: 3},
{ name: 'size 4', id: 4}
]),
selectedSize : ko.observable(0),
};
vm.selectedSize.subscribe(function(newValue){
alert('Selected Size is ---> ' + newValue )
// Here at this point call your ajax or backend method and bind the values which are coming form
});
ko.applyBindings(vm);
<script src="https://cdnjs.cloudflare.com/ajax/libs/knockout/3.0.0/knockout-min.js"></script>
<select data-bind="
options: sizes,
optionsText: 'name',
optionsValue: 'id',
value: selectedSize,
optionsCaption: 'Choose Size...'"">
</select>
<select data-bind="
options: material,
optionsText: 'name',
optionsValue: 'id',
value: selectedMaterial,
optionsCaption: 'Choose Material...'"">
</select>
I know I am talking about only part of solution to your problem but, I think you need to divide your data object to bind it to various controls.

ng-repeat controller and parent update

I've been reading a lot on angular scopes and inheritance but I can't get my head around this problem. Here is the HTML I'm using:
<div class="sensorquery-sensor" ng-repeat="sensor in query.sensors" ng-controller="SensorsCtrl">
<select class="form-control"
ng-model="selected.sensor"
ng-options="sensor.name for sensor in parameters.sensors">
</select>
<select class="form-control"
ng-model="selected.definition"
ng-options="definition.value for definition in definitions">
</select>
<select class="form-control"
ng-model="selected.operation"
ng-options="operation for operation in operations">
</select>
</div>
As you can see, I have an ng-repeat based on query.sensors. The values stored in this query.sensors array should be simple:
{
name: 'sensor1',
type: 'temperature'
}
But I want to use a child controller: SensorsCtrl to handle more logic per sensor and hide the complexitiy of sensors. A sensor can look like:
{
name: 'sensor1',
attributes: [
'model',
'brand'
],
definitions: [
{
datatype: 'double',
value: 'temperature'
},
{
datatype: 'integer',
value: 'pressure'
},
{
datatype: 'string',
value: 'color'
}
]
}
So it's in my SensorsCtrl controller where I want to put the selection logic:
$scope.$watch('selected.sensor', function(sensor) {
$scope.definitions = sensor.template.definition;
});
$scope.$watch('selected.definition', function(definition) {
if (definition.datatype === 'string') {
$scope.operations = ['Count'];
} else {
$scope.operations = ['Max', 'Min'];
}
$scope.selected.operation = _.first($scope.operations);
});
How do I keep the link with the parent query.sensors[$index] while transforming the sensor as the user selects different sensors and definitions?
Setting up a watcher on selected and updating the query.sensors array triggers an infinite $digest loop.

I found the solution which was right before my eyes:
<div class="sensorquery-sensor" ng-repeat="sensor in query.sensors" ng-controller="SensorsCtrl">
<!-- ... -->
</div>
The sensor is a reference to the original object of the parent query.sensors. An it's created in the scope of the sub-controller.
So in my SensorsCtrl controller, I can just watch:
$scope.$watch('sensor.definition', function(definition) {
/* ... */
});
So I can put hide some complexity in this controller while maintaining a proper link to the original element.
It does not answer the question of maintaining a less complex object but it's a different question I guess.

Knockout observable array. Shared between multiple view models

Got a bit of a conundrum with a knockout observable array being shared across multiple view models.
Basically, I have a layout as follows
Transport
... textbox fields, etc
Selected Passengers:
<!-- ko foreach: allPassengers -->
<input type="checkbox" />
<!-- /ko -->
<button>Add Transport</button>
Holiday
... textbox fields, etc
Selected Passengers:
<!-- ko foreach: allPassengers -->
<input type="checkbox" />
<!-- /ko -->
<button>Add Holiday</button>
Now the selected passengers for each section is being generated from ONE observable array, idea being if a passenger is deleted/altered everything should fall into place automagically.
So something like this
function page() {
// in actuality this passengers array is a computed observable obtained from the passengers section which is not shown here.
this.allPassengers = ko.observableArray([
{
Id: 1,
name = ko.observable('name'),
checked = ko.observable(false)
},
{
.
.
]);
}
function transport() {
// pageVM is a page object
this.allPassengers = pageVM.allPassengers;
this.transportItems = ko.observableArray();
this.addTransport = function() {
this.transportItems.push({
.
.
selectedPassengers: [...]
.
.
});
};
}
function holiday() {
// pageVM is a page object
this.allPassengers = pageVM.allPassengers;
this.holidayItems = ko.observableArray();
this.addHoliday = function() {
this.holidayItems.push({
.
.
selectedPassengers: [...]
.
.
});
};
}
However, when add transport/holiday is clicked, I need a way to determine which checkboxs where checked so I can add the selected passengers.
I have tried to add a checked = ko.observable(false) property to the passenger item in parent.allPassengers, but the problem with this approach is if a checkbox is checked in the transport section it will also check it in the holiday section since it is using the same observable array.
Any ideas??
Edit:
example fiddle

The checked binding works with observable arrays too. So you can simply bind to $parent.selectedPassengers and specify the value attribute to be the passenger id, like this:
<input type="checkbox" data-bind="attr: { value: id },
checked: $parent.selectedPassengers" />
In each view model you need to have a selectedPassengers observable array used for binding to the checkbox. And the add function should look like this:
function transport(pageVM) {
....
this.selectedPassengers = ko.observableArray([]);
....
this.addTransport = function() {
this.selectedItems.push({
....
selectedPassengers: this.selectedPassengers()
});
};
};
Working Fiddle

You can use a ko.computed to return the selected passengers (and here's a fiddle):
var ViewModel = function () {
this.allPassengers = ko.observableArray([
{ name: 'John', selected: ko.observable(false) },
{ name: 'Jane', selected: ko.observable(false) },
{ name: 'Mark', selected: ko.observable(false) }
]);
this.selectedPassengers = ko.computed(function () {
return ko.utils.arrayFilter(this.allPassengers(), function (item) {
return item.selected();
});
}, this);
};

Knockout mapping - Uniquely identifying nested objects using keys

The Knockout mapping plugin documentation has a section entitled "Uniquely identifying objects using “keys”". This describes how to update part of an object and then only update that part of the display rather than completely replacing the display of all properties of a partially-modified object. That all works splendidly in their simple example, which I have slightly modified here to make my question more clear. My modifications were to:
Replace the object with a corrected name after a 2 second delay.
Highlight the unchanging part of the display, so you can see that it is actually not replaced when the update happens.
1. Simple object (jsFiddle)
<h1 data-bind="text: name"></h1>
<ul data-bind="foreach: children">
<li><span class="id" data-bind="text: id"></span> <span data-bind="text: name"></span></li>
</ul>
<script>
var data = {
name: 'Scot',
children: [
{id : 1, name : 'Alicw'}
]
};
var mapping = {
children: {
key: function(data) {
console.log(data);
return ko.utils.unwrapObservable(data.id);
}
}
};
var viewModel = ko.mapping.fromJS(data, mapping);
ko.applyBindings(viewModel);
var range = document.createRange();
range.selectNode(document.getElementsByClassName("id")[0]);
window.getSelection().addRange(range);
setTimeout(function () {
var data = {
name: 'Scott',
children: [
{id : 1, name : 'Alice'}
]
};
ko.mapping.fromJS(data, viewModel);
}, 2000);
</script>
But what isn't clear to me is how I would achieve the same behavior for a more complex nested data structure. In the following example, I took the above code and wrapped the data in a list. I would like this to behave the same as above, but it doesn't. The whole display is redone because of the change in one property. You can see this because, unlike the above example, the highlighting is lost after the data is updated.
2. More complex nested object (jsFiddle)
<!-- ko foreach: parents -->
<h1 data-bind="text: name"></h1>
<ul data-bind="foreach: children">
<li><span class="id" data-bind="text: id"></span> <span data-bind="text: name"></span></li>
</ul>
<!-- /ko -->
<script>
var data = {
parents: [
{
name: 'Scot',
children: [
{id : 1, name : 'Alicw'}
]
}
]
};
var mapping = {
children: {
key: function(data) {
console.log(data);
return ko.utils.unwrapObservable(data.id);
}
}
};
var viewModel = ko.mapping.fromJS(data, mapping);
ko.applyBindings(viewModel);
var range = document.createRange();
range.selectNode(document.getElementsByClassName("id")[0]);
window.getSelection().addRange(range);
setTimeout(function () {
var data = {
parents: [
{
name: 'Scott',
children: [
{id : 1, name : 'Alice'}
]
}
]
};
ko.mapping.fromJS(data, viewModel);
}, 2000);
</script>
So basically what I'm asking is, how can I make the second example work like the first, given the more nested data structure? You can assume that ids are unique for each child (so if I added another parent besides Scott, his children would start with id=2, etc.).

Interesting observation there and nice write-up. It appears to work if you define a key on the parent as well as the child. Try this fiddle:
http://jsfiddle.net/8QJe7/6/
It defines instantiable view model functions for the parents and children, where the parent constructor does its child mappings.