I am using angular (^8.2.14) and ag-grid-community (^20.1.0).
I try to achieve the following effect: when the user hovers a specific row, one column shows an additional button which may be clicked.
What does work?
The column with the wanted behaviour gets rendered by a custom cell renderer component which implements the ICellRendererAngularComponent interface. There I can inject the ElementRef and on the lifecycle hook AfterContentChecked I check the parents' parent for the css-class 'ag-row-hover' and if it's there, I will show this additional button in the renderer component.
custom-cell.component.ts
#Component({
selector: 'app-custom-cell',
template: `
<ng-container *ngIf="hovered; else notHovered">{{form.value * form.value}}
<button (click)="doStuff(form.value)">show root</button></ng-container>
<ng-template #notHovered>{{form.value + form.value}}</ng-template>
`,
})
export class CustomCellComponent implements ICellRendererAngularComp, AfterContentChecked {
form: FormControl;
params: ICellRendererParams;
hovered = false;
constructor(private elementRef: ElementRef) {
}
doStuff(val) {
alert(val);
}
ngAfterContentChecked() {
this.hovered = (this.elementRef.nativeElement as HTMLElement)
.parentElement
.parentElement
.classList.contains('ag-row-hover');
}
}
The source code for this is on github
What do I want to improve?
I want to improve the performance and not having explicit checks for this behaviour. I'd rather have a directive with the css-selector '.ag-row', which I can inject to the ICellRendererAngularComponent and then check for the css class '.ag-row-hover' on every check. Or have a directive with the css-selector '.ag-row-hover' which is there, or is not. Anyone has any ideas how to improve my existing solution?
You could actually achieve the desired behavior with CSS only, no need to inject ElementRef or do anything via Angular Lifecycle Callbacks.
That being said, your custom renderer could look something like this:
#Component({
selector: "app-custom-cell",
template: `
<span style="color: red;">
<div class="visible-on-hover">
{{ form.value * form.value }}
<button (click)="doStuff(form.value)">show root</button>
</div>
<div class="hidden-on-hover">{{ form.value + form.value }}</div>
</span>
`
})
export class CustomCellComponent
implements ICellRendererAngularComp {
form: FormControl;
params: ICellRendererParams;
constructor() {}
doStuff(val) {
alert(val);
}
//... other stuff
}
In your styles.scss (or somewhere it fits better, just make sure the styles apply), just add these rules:
div.visible-on-hover {
display: none;
}
.ag-row-hover {
div.visible-on-hover {
display: block;
}
div.hidden-on-hover {
display: none;
}
}
Conceptually, the browser rendering engine then does what you did in ngAfterContentChecked().
Related
I have a component which is reusable. This component is called from parent component multiply times and sometimes the background page of the parent component is white and sometimes is black.
My child component generates form tags dynamycally - inputs,selects, textarea.
That means i can't have fixed styles in my css in my component for my content.
So when when the background page is white - i have one style for my inputs - for example black background. When the background page is black i have another style for my inputs - for example white bacgrkound.
To solve this is issue:
i tried
Adding input property in my child component ts file
#Input()
public cssTemplate;
in html
<div [ngClass]="{'form-group-white-bg': cssTemplate == 'white', 'form-group-dark-bg': cssTemplate == 'black'}">
<label for=""></label>
....
In the CHILD component i am sending value for input property depending on where the child component is called
if it is called on page with white background
<app-form-group cssTemplate="black" formControlName="address">
</app-form-group>
if it is called on black bacgrkound
<app-form-group cssTemplate="white" formControlName="address" [data]="{ field: 'address', label: 'Address' }">
</app-form-group>
but the problem here is that sometimes on my parent component this component is called multiply times
on one page can be called 12 times where i need 10 inputs and 2 selects
on other page can be called 15 times etc.
That means that i need to repat my self 15 times
<app-form-group cssTemplate="white" formControlName="address">
</app-form-group>
<app-form-group cssTemplate="white" formControlName="someItherControlName">
</app-form-group>
and everywhere to put cssTemplate="white".
ngFor is not an optin because this child component is called multiply times but not on same place in the HTML structure in the parent.
How can i solve this DRY?
you can add styles in your styles.css (the styles general for all the application). If e.g. you has
.white h1{
color:red;
}
.black h1{
color:green;
}
You can use [ngClass] in the "parent"
<div [ngClass]="toogle?'white':'black'">
<hello name="{{ name }}"></hello>
</div>
<button (click)="toogle=!toogle">toogle</button>
See [stackblitz][1]
NOTE: I used the way [ngClass]="expresion" (where expresion use conditional operator) better that [ngClass]="{'classname1':condition;'classname2':!condition}"
Update about your comment "how can i prevent repeating my self on child call", really I don't understand so much. I don't know if you want to make a directive like, e.g.
#Directive({
selector: 'hello', //<--the selector is the selector of the component
exportAs: 'helloDiv'
})
export class HelloDirective implements OnInit{
constructor(#Self() private component:HelloComponent,private dataService:DataService){
}
ngOnInit(){
console.log(this.component.name)
this.dataService.theme.subscribe(res=>{
this.component.theme=res;
})
}
}
This allow to "extends" the component -in the stackblitz the variable "theme" change-
[1]: https://stackblitz.com/edit/angular-ivy-sjwxyq?file=src%2Fapp%2Fapp.component.html
You can use an input property to create a css class map to pass on to ngClass. This object should be an object of string arrays.
It can be pretty much as complex and contain as many classes and rules as you need it too
#Input() color: 'white' | 'red' | 'hotpink' = 'white';
classMap: any;
ngOnInit() {
this.updateClassMap();
}
updateClassMap() {
this.classMap = {
[this.color]: !!this.color, // Add this class if not null
};
}
Then in the Html simply pass it to ngClass
<div [ngClass]="classMap">
Styling Child Components depending on Parent Component
There are two approaches I commonly take in this scenario
:ng-deep - create a style rule based on a class which is set in your parent component
utilize #ContentChildren() to set a property directly on your child components and call detectChanges() manually after the change.
To adopt the first solution you need to exercise greater care in your css naming rules, as using ng-deep obviously breaks the isolation of those style rules.
To adopt the second approach needs some considering due to it technically circumventing the standard input/output flow in Angular and thus can be a bit of a surprise "undocumented behavior" for any other maintainers of the application.
I'm a bit on the fence whether I prefer one approach over the other. The first approach seems more trivial to me, but it can also cause unintended style rule overwrites, while the second approach involves a lot more scripting and seems a bit of a hack.
Approach 1: ng-deep
Give your parent component an input and update a class on a block-element wrapping your <ng-content>.
create your desired style rules in your child component.
// parent component
#Component(...)
export class FooParent {
#Input() bgStyle: 'light' | 'dark' = 'light';
}
<!-- parent component template -->
<div class="parent" [ngClass]="{light: bgStyle == 'light', dark: bgStyle == 'dark'}">
<ng-content></ng-content>
</div>
// child.css
::ng-deep .light .child-container {
background-color: lightblue;
}
::ng-deep .dark .child-container {
background-color: royalblue;
}
My targeted element in the example is .child-container, you would write a similar style rule for each element you want to affect.
Approach 2: Using ContentChildren to pass along a value
Add a #ContentChildren() decorator to your parent component which selects for your child components.
inject a ChangeDetectorRef
implement ngAfterViewInit to loop through each child and set the value
call detectChanges() once done.
add the ngClass directive as normally in your child component.
Parent
#Component({
selector: 'parent',
templateUrl: 'parent.component.html',
styleUrls: ['parent.component.scss']
})
export class ParentComponent implements AfterViewInit, OnChanges {
#Input() bgStyle: 'light' | 'dark' = 'light';
#ContentChildren(ChildComponent) childComponents!: QueryList<ChildComponent>;
constructor(private change: ChangeDetectorRef) {
}
ngOnChanges(changes: SimpleChanges) {
if ('bgStyle' in changes) {
this.updateChildComponents();
}
}
updateChildComponents() {
this.childComponents.forEach(child => {
child.bgStyle = this.bgStyle;
});
this.change.detectChanges();
}
ngAfterViewInit() {
this.updateChildComponents();
}
}
<!-- parent.component.html -->
<ng-content></ng-content>
Child
#Component({
selector: 'child',
templateUrl: 'child.component.html',
styleUrls: ['child.component.scss']
})
export class ChildComponent implements OnInit {
bgStyle: 'light' | 'dark' = 'light';
constructor() {
}
ngOnInit(): void {
}
}
<!-- child.component.html -->
<div [ngClass]="{light: bgStyle == 'light', dark: bgStyle == 'dark'}" class="child-container"></div>
// child.component.css - you would apply styles as you needed obviously.
.child-container {
width: 40px;
height: 40px;
margin: .5rem;
}
.light.child-container {
background-color: lightblue;
}
.dark.child-container {
background-color: royalblue;
}
Usage
<!-- any other template -->
<parent>
<child></child>
<child></child>
<child></child>
</parent>
Note: If you are creating the ChildComponent directly in the ParentComponent's own template you need to use #ViewChildren instead of #ContentChildren
Usually, I can style the very root of my component by using the :host pseudo style like this.
:host{ border: 1px solid gold; }
But how shold I handle if said style is supposed to be set dynamically, based on the parameters passed to #Input?
The only way I can think of at the moment is to add an auxilliary DIV and style it like so.
<div [ngClass]="styleMeDynamically"> ... </div>
Is there a way to apply a style dynamically directly on the host without the injected DIV?
I've found this suggestion but it requires explicitly stating the classes and connecting them to separate inputs. I'd like to get a config object as passed in parameter and bind the styling using [ngClass] to retail full flexibility.
Probably #HostBinding decorator can help you. It allows to bind any host attribute including class and style. For example:
#Component({ ... })
export class MyComponent {
// you can conditionally add a class to the host element
#Input()
#HostBinding('class.large')
large = false;
// it's possible to bind a style as well
#Input()
#HostBinding('style.border.px')
borderWidth = 1;
#Input()
green = false;
// and you can use a getter
#HostBinding('style.border-color')
get borderColorStyle() {
return this.green ? 'green' : 'black';
}
}
Since angular 9 it should be possible even to bind a CSS variable, see Improved CSS class and style binding section of the 9 version release article.
<div [style.--main-border-color]=" '#CCC' ">
<p style="border: 1px solid var(--main-border-color)">hi</p>
</div>
What you can do is,
Create a custom directive that will accept a style object. and inside that directive, you can get the reference of host element and modify its style.
Here is a Demo
And here is a quick explanation.
Create a directive as which will accept a style object.
import {Directive,TemplateRef,ElementRef,OnChanges,SimpleChanges,OnInit,Renderer2,DoCheck,Input} from "#angular/core";
#Directive({
selector: "[appSetStyle]"
})
export class SetStyleDirective implements OnInit, OnChanges {
#Input() appSetStyle: { [key: string]: any } = {};
constructor(private elementRef: ElementRef<HTMLElement>) {}
ngOnInit(): void {}
ngOnChanges(changes: SimpleChanges): void {
this.applyStyles();
}
applyStyles(): void {
if (this.appSetStyle) {
for (const key in this.appSetStyle) {
this.elementRef.nativeElement.style[key] = this.appSetStyle[key];
}
}
}
}
Use that style object with any html element or any other component in your project.
<app-header [appSetStyle]="dynamicStyles"></app-header>
If you don't want to make a directive then you can inject the ElementRef inside the component itself which you want to style.
ElementRef is the what you need to use to get the reference of host.
I hope this will help.
I work on an Angular 6 app (with Bootstrap 4) and need to change the page background color depending on which page the user enters. Default is white, but for login and registration screen the page color needs to be blue.
What I found so far:
in ngAfterViewInit() using
this.elementRef.nativeElement.ownerDocument: this approach makes the
app more vulnerable to XSS attacks and I want to avoid that.
Set View Encapsulation to None in app.component.ts: this way I can
set the body color in the app.component, that is 1 step forward.
So, now I have in my app.component.css:
body {
background-color: blue;
}
Question:
How can I change that color value (in app.component) using a variable?
With [ngStyle] I can not reach the body background-color.
Maybe using a css variable? but how can I change the value of that css variable dynamically?
I'm new to Sass, but might this offer a solution?
My question is different from the other question on this subject as I need to be able tochange the color value dynamically.
use render2 and set class to body using document object
app.component.ts
constructor(private renderer: Renderer2) {
this.renderer.addClass(document.body, 'body-class');
}
Note: if you are toggling classes, just remove previous class before assigning new class
The way I would do it is based on the routes. When defining the routes, you can add extra data, for example a class name.
When the route changes (i.e. via navigation), the data from the active route can be used to set the class on the body tag.
This is how you can achieve this
Update the styles.css to add different classes for body:
body {
...
}
body.red {
background-color: #ff8181;
}
body.blue {
background-color: #a0c3ee;
}
Update the routes to add extra data, specifying the body class name. Add an extra data property, like bodyClass:
const routes: Routes = [
{ path: '', component: DefaultComponent },
{ path: 'red', component: RedComponent, data: { bodyClass: 'red' } },
{ path: 'blue', component: BlueComponent, data: { bodyClass: 'blue' } }
];
Write the code to read the bodyClass and set the class to the body element when navigation occurs. This can be done in the app.component.ts:
#Component({
selector: 'app-root',
template: `
<div>
<router-outlet></router-outlet>
<app-menu></app-menu>
</div>
`
})
export class AppComponent implements OnInit {
constructor(
#Inject(DOCUMENT) private document,
private renderer: Renderer2,
private router: Router,
private activatedRoute: ActivatedRoute) {
}
ngOnInit() {
this.router.events
.pipe(filter((event) => event instanceof NavigationEnd))
.pipe(map(() => this.activatedRoute))
.pipe(map((route) => {
while (route.firstChild) {
route = route.firstChild;
}
return route;
}))
.pipe(filter((route) => route.outlet === 'primary'))
.pipe(mergeMap((route) => route.data))
.subscribe((event) => this.updateBodyClass(event.bodyClass));
}
private updateBodyClass(customBodyClass?: string) {
this.renderer.setAttribute(this.document?.body, 'class', '');
if (customBodyClass) {
this.renderer.addClass(this.document?.body, customBodyClass);
}
}
}
Here is a demo on StackBlitz: https://stackblitz.com/edit/angular-ivy-rs1tai
Why not just define a separate class based on different background-color? For instance:
.blue {
background: blue
}
.green {
background: green
}
.grey {
background: grey
}
And then set these classes on the body using ng-class or ngClass whatever convention you use based on the page. This should be fairly easy to implement.
My favourite approach for doing stuff like this is to add a class to html tag depending on the route. For example, we have some code in our basic layout component (you could put it in your root component) that does this inside ngOnInit:
let wrapper = ''
const path = this.activatedRoute.snapshot.routeConfig.path
wrapper += this.tidyPath(path)
if (wrapper !== '') wrapper += '-'
const childPath = this.activatedRoute.snapshot.firstChild.routeConfig.path
wrapper += this.tidyPath(childPath)
this.routeWrapperCssClass = wrapper
$('html').addClass(this.routeWrapperCssClass)
This will add a class to your html tag to make it look like this (although you may have to tweak this code to suit your app):
<html class="registration">
....
</html>
The class will be instantly updated whenever you change route.
Now you can do this in your main stylesheet:
body {
background-color: pink;
}
html.registration body {
background-color: yellow;
}
You could also do things like hide elements based on the class added to the html tag like so:
.navbar {
display: block;
}
html.registration .navbar {
display: none;
}
Because you know what route you are on at all times you have total control via CSS.
PS you may want to use render2 instead of jQuery to do the DOM manipulation - see this article ... https://alligator.io/angular/using-renderer2 ... never used it myself before but almost identical to jQuery syntax - thanks to Pratap A.K answer for this
Personally i replace :
<body>
<app-root></app-root>
</body>
to
<app-root></app-root>
and then i add all the time the body on components or if i have multi
router-outlets i add it on app.component.css
I am using modular css in react. I have to addClass to a <h2> how do I do that the problem is I am using modular css I know how to do it in normal css.Please Help.
Here is my component
import React, { Component } from 'react';
import style from '../css/MessageHeader.css';
class MessageHeader extends Component {
constructor(props) {
super(props);
this.state = {
name : "name"
}
}
render(){
return(
<div className={style.container}>
<div className={style.iconWrapper}>
<i className ="fas fa-angle-left"></i>
</div>
<div className={style.profileWrapper}>
<h2 className={this.state.name}>john appleseed </h2> //this is how I would in normal css
</div>
</div>
);
}
}
export default MessageHeader;
This would help you add the className this way. Variable is any variable in state with classname
<h2 className={`${this.state.variable}`}></h2>
While you can use a global class, I'm assuming you also want the h2 classes to be scoped to that component. Just like your other classes, you need to reference the style import - but use a dynamic key based on the state, like so:
<h2 className={style[this.state.name]}>john appleseed </h2>
Then your css module MessageHeader.css should contain a class for all names that you want to custom styling for.
Example:
.container {
// some styles here
}
.johnAppleseed {
color: yellow;
}
// You can also specify a name as a child of the container just like normal css,
// although it's not really necessary
.container .bobBobbert {
color: red;
}
Keep in mind that if your name in the state has spaces, that isn't going to work for a css class name, so you'll have to do some transformation (e.g. this.state.name.replace(...) to remove spaces and/or punctuation.
Background
I have a component that wraps two span elements. I would like parent components to be able to style the inner two spans by specifying CSS classes and styles as inputs (preferably as simple strings). Here's a simplified example of what I would like this to look like:
Code
app component (parent)
#Component({
selector: 'my-app',
template: `
<div>
<app-two-spans [classArg1]="'class1'" [classArg2]="'class2'"
[styleArg1]="'width: 100px'" [styleArg2]="'width:200px'"></app-two-spans>
</div>
`, style: `
::ng-deep .class1 {
border: 1px solid black;
}
::ng-deep .class2 {
border: 1px solid blue;
}
`
})
export class App {
}
two spans component (child)
import {Component, Input, Output, EventEmitter} from '#angular/core';
#Component({
selector: 'app-two-spans',
template: `
<span *ngIf="flag" [ngClass]="classArg1" [ngStyle]="styleArg1"
(click)="flag = !flag">click me</span>
<span *ngIf="!flag" [ngClass]="classArg2" [ngStyle]="styleArg2"
(blur)="flag = !flag" contenteditable="true">
click me to change my value</span>
`
})
export class TwoSpansComponent {
flag: boolean = true;
#Input() styleArg1: string;
#Input() styleArg2: string;
#Input() classArg1: string;
#Input() classArg2: string;
constructor() {}
}
Problem
The class styling seems to work in my local environment (though it doesn't seem to work on Plunker for some reason). However, the styles are not showing up. I've seen other posts about styles as inputs, but from what I've seen this is usually done by passing style-value pairs (see accepted answer here). However, I would really like to pass these styles as a simple string to make working with the component easier.
I notice the following error in the console: ERROR Error: Cannot find a differ supporting object 'width: 100px'. I'm not sure what this means at all.
Plunker here
Is there a way to do this? How can I give parent components the ability to stylize children?
ngStyle accepts an Object instead of plain string. You can pass your styles as:
[styleArg1]="{ width: '100px' }"
[styleArg2]="{ width: '200px' }"