how to use angular material form field and flex-layout - angular-flex-layout

Question

I want to have 2 form input fields in one row:
1. the first has a fixed with,
1. the second should grow and shrink, but this does not shrink below 180px.
Here is a full stack-blitz example
When you start the app, we see this
There maybe another issue:
I think the 2nd input field should already show the hint text and the horizontal line - but it will only show it when it get's the focus.
Is this the expected behaviour or am I missing something?
Anyway. The main issue is that the 2nd field does not shrink as expected. It will not shrink below 180px:
In the chrome dev-tool I can see that the input element is wrapped with a div class="mat-form-field-infix"> and the class mat-form-field-infix has a fixed width of 180px!
The only workaround that I came up with is to override this width with using ::ng-deep.
You can activate this in the co-input-field.component.scss file of the Stackblitz example
:host ::ng-deep .mat-form-field-infix {
// width: auto !important;
width: unset !important;
}
With this workaround the 2nd input shrinks as expected:
But ::ng-deep is deprecated and will be removed.
So what is the right way to make the input shrink as expected?

Answer 1

since .mat-form-field-infix has a fixed width of 180px there is no way of making form field shrink beyond 180px. inevitably .mat-form-field-infix must be overridden.
you can achive the same result with ::ng-deep in a couple of ways;
1.disable view encapsulation for that particular component. However, this approach has a huge drawback that all the styles in your component becomes global so they need to be managed carefully.
#Component({
selector: 'app-co-input-field',
templateUrl: './co-input-field.component.html',
styleUrls: ['./co-input-field.component.scss'],
encapsulation: ViewEncapsulation.None
})
export class CoInputFieldComponent {}
and then in co-input-field.component.scss you do the following
app-co-input-field {
.mat-form-field-infix {
width: auto !important;
}
// all other component styles goes in here
// in order to keep them isolated from global scope
}
2.don't disable view encapsulation. use the element selector of parent component in global styles.
put the following in styles.scss
app-co-input-field {
.mat-form-field-infix {
width: auto !important;
}
// co-input-field.component.scss still can be used for encapsulated styles
}
3.don't disable view encapsulation. define a global rule for this particular situation.
put the following in styles.scss
.shrinking-mat-form-field {
.mat-form-field-infix {
width: auto !important;
}
}
and apply the .shrinking-mat-form-field class to corresponding element
<mat-form-field style="width: 100%" class="shrinking-mat-form-field">
<input matInput placeholder="placeholder" />
<mat-hint align="end">hint text</mat-hint>
</mat-form-field>
Even though second and third approaches are fundamentally same I personally prefer the third approach in order to make it readable, keep it consistent over the project, have minimal side effects and manage them from a single point.

Answer 2

:host ::ng-deep.mat-form-field-appearance-legacy .mat-form-field-infix {
padding: 0.4375em 0;
display: flex;
}