I'm new to AngularJS and have been assigned a maintenance task on an app we've inherited (originally developed for us by a third-party).
At the left of a header row in a table is a small button showing either a plus (+) or minus (-) symbol to indicate whether it will expand or collapse the section when clicked. It does this using ngClass as follows.
ng-class="{false:'icon-plus',true:'icon-minus'}[day.expanded]"
I have to remove the button when there is no data in the section and thus no ability to expand. There is already a class (.plus-placeholder) for this and I was wondering if the expressions that ngClass uses can be nested to allow something like this
ng-class="{false:'plus-placeholder',true:{false:'icon-plus',true:'icon-minus'}[day.expanded]}[day.hasTrips]"
which would allow me to add a hasTrips property to day to accomplish the task.
If this is not possible I think I will need to add a property something like expandoState that returns strings 'collapsed', 'expanded' and 'empty'. so I can code the ngClass like this
ng-class="{'collapsed':'icon-plus','expanded':'icon-minus','empty':'plus-placeholder'}[day.expandoState]"
And perhaps this is a cleaner way to do it in any case. Any thoughts/suggestions? Should it be relevant, the app is using AngularJS v1.0.2.
You certainly can do either of the two options you have mentioned. The second is far preferable to the first in terms of readable code.
The expandoState property you mention should probably be a property or a method placed on the scope. Your attribute would then read something like
ng-class="{'collapsed':'icon-plus','expanded':'icon-minus','empty':'plus-placeholder'}[expandoState()]"
To put this method on the scope you would need to find the relevant controller. This will probably be wherever day is assigned to the scope. Just add
$scope.expandoState = function() {
// Return current state name, based on $scope.day
};
Alternatively, you could write a method on the controller like
$scope.buttonClass = function() {
// Return button class name, based on $scope.day
};
that just returns the class to use. This will let you write the logic from your first option in a much more readable fashion. Then you can use
ng-class="buttonClass()"
Related
I am working on a project with a PHP backend and Angular 1.x on the front end. I have a Listings model and I use a common template to create (add) and update (edit) a Listing.
Since eidt and add both use the same front end template I need to be able to detect when a user is creating and when they are editing. It seems there are several ways to do this:
I could pass a paramater in the ng-submit:
ng-submit="saveListing({{isNewListing}}"
Then I could read the value of the paramter in my controller, but I think this is overkill?
When editing a Listing some variables set for the form auto-fill
$scope.listing.id = x;
Therfore I could just check for a value in the above:
$scope.saveListing = function() {
if(listing.id) {
// update action
} else {
// save action
}
};
Is the second option a sound and non-hacky approach. I am not an Angular pro so although it seems the logical approach to me I want to ensure that I am not hot woring this.
I usually do something similar to the second approach. Since editing means you have to "get" the original record in most cases, the record should exist somewhere in the scope. I use ui-router and have a resolve for the record, which means I can check right at the top of the controller:
$scope.isEdit = record != null;
With a scope variable or similar (e.g. controllerAs vm) you can leverage the fact that you're in "edit mode" and change the UI up a bit. Instead of "+ New" on a button you can have "+ Save".
Hope that helps!
We have a large ERP system with angularJs as a front-end framework, and we are using the "check id" approach.
When updating/edit an item there would be existing id for that item.
I think the second approach is good and I don't see any drawbacks.
I have a lightning-card in lightning web component (LWC) and want to set the label attribute with two different variables. Although this can be done through the controller but I want to do this in html file itself.
As in the code snippet, I am assigning {cardTitle} as a title, but I have another variable {totalCount} and want to concatenate the totalCount along with the cardTitle here. So lightning-card should have title like "{cardTitle}{totalCount}".
<lightning-card title={cardTitle}></lightning-card>
//In Controler js
#track cardTitle = 'Student details';
#track totalCount = 0; //This will be set by the apex controller later and will have dynamic number
When I try below code
<lightning-card title={cardTitle}{totalCount}></lightning-card>
It shows error as
multiple expressions found
.
No. You can only do it in controller JavaScript file.
I love part of the answer on SF stackexchange so I'm going to quote it here:
Your concerns about separating UI from controller logic do not apply
here as this is not a "controller". That MVC pattern is an Aura-ism.
This is the code which drives your component's functionality so it
makes sense that your JS would know about class names.
It's different but think about it that way - it'll let you write a proper unit test for the JavaScript. How you'd test logic that exists only in HTML layer? Or only in Visualforce page markup?
You can have only one expression. If you read documentation like https://developer.salesforce.com/docs/component-library/documentation/lwc/lwc.reference_directives
you'll see
The expression can be a JavaScript identifier (for example, person) or dot notation that accesses a property from an object (person.firstName). The engine doesn’t allow computed expressions (person2.name['John']). To compute the value of expression, use a getter in the JavaScript class.
I'm relatively new to AngularJS and the problem I'm facing is one of those "I want to inject a Service into an app.config" type of scenarios, which I realise cannot be done. (I'm comfortable with the different between Service and Provider, and why a Service cannot be injected into a .config.)
What I am trying to accomplish is to use angular-schema-form together with angular-translate such that field titles in generated forms are translated.
There is an issue where someone asks how to do this, and the advice given is to take advantage of angular-schema-form's postProcess, which is a property of the Provider. This callback gives you the form object before it is rendered, giving you the opportunity to manipulate it with user code. Therefore translation could be done within here.
The postProcess method is called on the Provider, so it is done within an app.config:
app.config(function(schemaFormProvider, $translateProvider) {
schemaFormProvider.postProcess(function(form){
// within here I can inspect the form object, find all
// properties whose key is "title", and then perform
// language translation on their values.
So, that is apparently the place where I have an opportunity to manipulate control titles and so on.
Over to the angular-translate library, for me to 'manually' translate strings, I can use the $translate service. This provides both synchronous and asynchronous methods to translate a given key string. The synchronous one is $translate.instant(key).
To glue these two together, what I have tried so far (which does work) is to create a 'bridge' method like this:
var app = angular.module('myApplicationName', ['schemaForm', 'pascalprecht.translate']);
....
app.config(function(schemaFormProvider, $translateProvider) {
schemaFormProvider.postProcess(function(form){
// ... code here which iterates over properties
// and finds all control titles ...
key = app.myTranslate(key);
// ....
}
....
});
app.myTranslate = function (key) {
var service = angular.injector(['ng', 'myApplicationName']).get("$translate");
return service.instant(key);
}
This does work, but it seems ugly and unsafe (as presumably there's no guarantee $translate is ready when the callback is first invoked) and the calls to angular.injector(['ng', 'myApplicationName']).get... are presumably expensive.
Is there a better way, or is this the only way I'm going to get it done, considering the constraints of the libraries I'm working with?
I have also considered an alternative approach altogether, which would be to instead perform the translations on the schema or form objects before they are processed by angular-schema-form. This could be done from within Controllers, eliminating the problem of accessing the $translate service. I may end up going down that route, but it would still be nice to understand the best solution for the above scenario.
I couldn't find an answer or a solution to a challenge yet: How can I bind a variable (Session variable, no mongo collection) reactively in angular-meteor?
I'm converting from standalone meteor. Here I could use the template.helper method. As I can't use templates (and iron:router) anymore with angular-meteor and angularui-router, I can't bind reactivity to the helper anymore (at least in my understanding).
I tried this in an meteor-angular controller, which belongs to a sentence.tpl file:
$scope.parsestring = function(input_string){
tokenizer(input_string);
};
$scope.sentence_type = Session.getJSON("current_sentence.sentence_type");
Tokenizing works (I can see it in the debugger), but the value is only displayed, when I reload the page. What I want to achieve is tokenizing a string from an input field into a JSON representation (the tokenizer takes care of that) and displaying it similtaniously from the JSON representation in a structured way (separate html input elements, which are created dynamically). sentence_type is the variable that should be used on the html-page to show and change the sentence type, which can change while typing.
Anybody has some hints? Maybe, I could also use some Angular feature that I don't know?
Cheers,
Jan
Code repo:
My current code looks like this:
My code looks similar to this:
angular.module('ngaignt').controller("InteractorCtrl", ['$scope', '$meteor', '$meteorCollection',
function ($scope, $meteor, $meteorCollection) {
// Autorun is necessary to make reactive variables out of the JSON returns
var c = Tracker.autorun(function (comp) {
$scope.verb_type = Session.getJSON("current_verb.type");
$scope.object_type = Session.getJSON("current_object.type");
$scope.verb_attributes = _.toArray(Session.getJSON("current_verb.attributes"));
$scope.object_attributes = _.toArray(Session.getJSON("current_object.attributes"));
if (!comp.firstRun) {
// only do not do aply at first run becaulse then apply is already running.
$scope.$apply();
}
});
$scope.parsestring = function (input_string) {
interactor(input_string);
};
//$scope.on('$destroy', function () {c.stop()});
}]);
To use reactive variables, you need a reactive computation. You may need to use Tracker.autorun:
$scope.parsestring = Tracker.autorun(function(someStringInSession){
tokenizer(Session.get(someStringInSession));
});
Or you can use Tracker.autorun(func) wherever you use a reactive variable to reactively rerun a function when the variable changes.
good question and the best answer depend on your needs.
There are 2 possible solutions:
If you want to bind a Session variable to a scope variable, use the $meteorSession service.
What it does is that every time the scope variable will change, it will change to Session variable (and trigger an autorun if it's placed inside one).
and every time the Session variable will change, the scope variable will change as well (and change the view that it's placed upon).
If you are using the Session variable just to get a variable reactive (meaning trigger an autorun), you should use getReactively . this just returns the already existing scope variable but trigger an autorun every time it changes. a good example of this can be found it our tutorial.
Note: In anyway, when you use Tracker.autorun inside Angular, you need to connect it to a scope. this can be easily done if you replace Tracker.autorun with the $meteorUtils autorun function
Would be great if you could share a repo so that I can look on the broader perspective and could better determine what's the best solution from the two.
Based on another answer about "session" reacitivity, I could solve the problem. Just use the approach described in the link https://stackoverflow.com/a/21046935/4035797. You have to substitute Deps.autorun by Tracker.autorun though as Deps is deprecated and you have to make the scope variables for use in the template reactive (e.g., $scope.sentence_type = Session.getJSON("current_sentence.sentence_type");) and not the tokenizer.
I'm using typeahead through in my AngularJS project and I would like to have it select the entry if I type the full value and click out of the field.
I've put together an example of what I mean
http://plnkr.co/edit/NI4DZSXofZWdQvz0Y0z0?p=preview
<input class='typeahead' type="text" sf-typeahead options="exampleOptions" datasets="numbersDataset" ng-model="selectedNumber">
If I type in 'two' and click on 'two' from the drop down then I get the full object {id: 2, name: 'two'}. This is good, if however I type 'two' and click to the next field without selecting is there a way to accept the top of the list on loss of focus on a text field?
I'm not sure if I'd want to have that sort of functionality in my app. The user hasn't actually selected anything. So selecting something for them would introduce frustrations.
But I do understand that often odd requirements are needed. In this case, I'd attack it using ngBlur. Assign a function to be called on blur. You can grab the contents of ng-model and then loop through your data (assuming static & not being sent via server) to find a match.
You can most likely just look at the source code of your typeahead directive and strip out the part does the comparison and then choose the first item in the array.
Unfortunately the underlying component does not emit any events for this condition. This will make the solution more complex. However when the value is being entered and the Typehead magic has happened you can supplement those events and catch them to update your ngModel.
I have created a plnkr based on your plnkr and although have not cleaned up but it is a working plnkr doing by far what you need.
The gist of this is following code however you can put this code wherever best suited
The explanation below:
//Crux - this gets you the Typeahead object
var typeahead = element.data('ttTypeahead');
//This gets you the first
var datum = typeahead.dropdown.getDatumForTopSuggestion();
if (datum){
//you can do lot of things here however
//..I tried to - fill in the functionality best suited to be provided by Typeahead
//for your use case. In future if Typeahead gets this
//..feature you could remove this code
typeahead.eventBus.trigger("hasselections", datum.raw, datum.datasetName);
}
In the above code you can also save the datum somewhere in the scope for doing whatever you like with it later. This is essentially your object {num: 'Six'} Then you may also use ngBlur to set it somewhere (however the plnkr I created doe snot need these gimmicks.)
Then further down - ngModel's value is set as below
element.bind('typeahead:hasselections', function(object, suggestion, dataset) {
$timeout(function(){
ngModel.$setViewValue(suggestion);
}, 1);
//scope.$emit('typeahead:hasselections', suggestion, dataset);
});
I'm with EnigmaRM in that ngBlur seems to be the way to do what you want. However, I agree with the others that this could be somewhat strange for the end users. My implementation is below (and in plnkr). Note that I trigger on ngBlur, but only apply the model if and only if there is only one match from Bloodhound and the match is exact. I think this is probably the best of both worlds, and hope it should give you enough to go on.
$scope.validateValue = function() {
typedValue = $scope.selectedNumber;
if(typedValue.num !== undefined && typedValue.num !== null)
{
return;
}
numbers.get(typedValue, function(suggestions) {
if(suggestions.length == 1 && suggestions[0].num === typedValue) {
$scope.selectedNumber = suggestions[0];
}
});
};