In one of my projects I did some renaming, following which some of the magic strings remained unchanged, and the bug of course took some time to surface. I was getting errors in the console as well as the compiler and IDE when using the SimpleChanges type in the function signature. To prevent the errors, use the any keyword in the signature instead. Use the ngOnChanges() lifecycle method in your component. I’m working on a personal project with Angular 17, and there are some settings that I get from the backend of my application. But my Angular HttpClient does not work and honestly I don’t know why not.
I have most of this working fine i.e. each component can access the json api and get its relevant data via observables. In app.config.ts we need to import provideHttpClient() in provider Array. If you need to pass some data, replace void (in EventEmitter) with desired type.
Angular CLI 1.x.x (Works with Angular 4.x.x, 5.x.x)
- I have a div that I want to style based on a condition.
- Currently video list component just gets all videos, I would like to filter this to just videos in a particular category, I achieved this by passing the categoryId to the child via @Input().
- This seems to be because the Angular compiler will not be shipped with the production builds as the templates are compiled “Ahead of Time”.
- I just want to add that there is another Lifecycle hook called DoCheck that is useful if the @Input value is not a primitive value.
- Then anywhere else in the code, this can be referenced as this.categoryId because the getter automatically gets called when referencing that in TypeScript.
Even if they label the old syntax as deprecated, it should still be usable, given the prevalence of applications employing this format. Furthermore, there’s no need to be concerned about migrating from the old syntax to the new one, as you can easily accomplish it by running the following command. By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy. The FormErrorSupportService has a static method that will actually construct the error text based on the error property.
How to detect when an @Input() value changes in Angular?
Quicker (and dirtier) solution to this would be to set type as any and pass whatever object you want. User ‘s answer is neat and more genericHowever, based on the request by Imad El Hitti, a light weight solution is proposed here. This can be used when a child component is tightly connected to one parent only. A button’sdisabled property is false by default so the button is enabled. Whenyou add the disabled attribute, its presence alone initializes thebutton’s disabled property to true so the button is disabled.
Answers 9
- And most important as the question here is about – you only need to ship a few files to production.
- The ngOnChanges() is an inbuilt Angular callback method that is invoked immediately after the default change detector has checked data-bound properties if at least one has changed.
- My experience with Angular 2 so far is that AoT creates the smallest builds with almost no loading time.
- They are overly-complicated even if they do ultimately work.
- I have some inputs (Checkboxes) and I want them to be disabled if my Booleans are true.But its not working…
I have a div that I want to style based on a condition. Sometime, I have to use ‘ChangeDetectorRef’ to refresh ui, then all disabled states work well. At the angular dynamic locale current version you need to to specify –aot manually, because it can be used in development mode (although that’s not practical due to slowness).
to 17 (TypeScript) with Angular CLI
I needed access to the data in CustomRouteReuseStrategy and I couldn’t inject the Router there due to a circular dependency but you can use the Location object to read the state as well. And I thought it to be the error in my ngClass condition, but it turned out the property I was trying to access in the condition of ngClass was not initialized. When the form is valid, button has btn and btn-class (from bootstrap), otherwise just btn class. Find centralized, trusted content and collaborate around the technologies you use most.
Example with passing object as parameter
Please try below CLI command in current project directory. So you can upload all files within dist folder for deployments. There are times when you only care about the smallest possible single bundle, but in large apps you may have to consider lazy loading. At some point it becomes impractical to serve the entire app as a single bundle. My experience with Angular 2 so far is that AoT creates the smallest builds with almost no loading time. And most important as the question here is about – you only need to ship a few files to production.
The safest bet is to go with a shared service instead of a @Input parameter.Also, @Input parameter does not detect changes in complex nested object type. This works since the library defines an input property for passing in a “disabled” value, i.e. @Input(‘disabled’). I ended up reading a lot of community input and ended up using the ngDoCheck function.
It could be improved upon by e.g. checking if there actual was a change. You have to import the HttpClientModule, not provide it. So remove it from the provides array and add it to the imports array. I have created a child component which has a method I want to invoke. If you are using bootstrap and apply any background colour using class, just remove it.
The funny thing is the submit button works just fine and thats the same method… This also performs AoT compilation for even smaller bundles (no Angular compiler, instead, generated compiler output). The bundles are much smaller with AoT if you use Angular 4 as the generated code is smaller.You can test your app with AoT in development mode (sourcemaps, no minification) and AoT by running ng build –aot. Connect and share knowledge within a single location that is structured and easy to search.
Adding and removing the disabled attribute disables and enables thebutton. The value of the attribute is irrelevant, which is why youcannot enable a button by writing Still Disabled. Latest version of angular (7.2 +) now has the option to pass additional information using NavigationExtras. 4) You can use a service to pass data from one component to another without using route parameters at all.
It’s also very cool to see your HTML template markup transformed to javascript instructions that would be very hard to reverse engineer into the original HTML. In older versions it also created gzipped versions for checking their size, and .map sourcemaps files, but this is no longer happening as people kept asking to remove these. I copied this tutorial and extended with some simple gulp tasks for bundling everything to dist folder which can be copied to server and work just like that.
I created and placed the files from the tutorial in a small GitHub seed project. Please include the Angular version within answers so we can track better when it moves to later releases. They are fully functional and polished, but that they are not ready tostabilize under their normal deprecation policy. The code is a good example of an ngClass if-else condition.
Angular: conditional class with *ngClass
For a production usage, you have to deploy all the files from the dist folder in the HTTP server of your choice. What is the best method to bundle Angular (version 2, 4, 6, …) for production on a live web server. While the Angular team hasn’t officially stabilized the control_flow yet, the definitive answer remains uncertain.
If styleOne is true I want a background colour of red. If StyleTwo is true, I want the background colour to be blue. In below example code, the child will be notified each time ‘tellChild()’ is called. This time we are given four files instead of the five. The –prod flag tells Angular to make our application much smaller in size. This seems to be because the Angular compiler will not be shipped with the production builds as the templates are compiled “Ahead of Time”.
I tried to optimize everything to work well on Jenkis CI, so node_modules can be cached and don’t need to be copied. Basically both suggested solutions work fine in most cases.My main negative experience with ngOnChange() is the lack of type safety. I then implement some custom checking code to decide if I want to update my view with the changed Array. Currently video list component just gets all videos, I would like to filter this to just videos in a particular category, I achieved this by passing the categoryId to the child via @Input().