bug(MatDatePicker, MatStepper): Min/Max validation on Datepicker doesn't update on step change in Stepper

[patrykp57]

Reproduction

https://stackblitz.com/edit/angular-9-material-starter-ctvwko

Steps to reproduce:

1. Set dates on step one to be valid (for example: 20/07/2020 - 27/07/2020)
2. Go to step two on mat-stepper then back to step one.
3. Change dates to be the same (25/07/2020 - 25/07/2020)
4. Go to step two on mat-stepper then back to step one.
5. Change dates to be in range from first repro step and different than step 3. (for example 20/07/2020 - 23/07/2020).
6. Error appear { "matDatepickerMin": { "min": "2020-07-24T22:00:00.000Z", "actual": "2020-07-22T22:00:00.000Z" } }. It's min date from repro step 3.

Expected Behavior

Error shouldn't appear as date is in valid range.

Actual Behavior

Datepicker doesn't revalidate form control when step is changed.

Environment

• Angular: 9.1.2
• CDK/Material: 9.2.1
• Browser(s): All
• Operating System: Windows

[jcimoch]

I've change it to this and it's working now. Probably shouldn't put formGroupName on ng-container with ngIf inside step, but didn't have time to investigate further.

<form [formGroup]="form">
<mat-horizontal-stepper [linear]="true" #stepper>
    <mat-step [stepControl]="form.get('stepOne')">
        <div [hidden]="stepper.selectedIndex !== 0" formGroupName="stepOne">
        <input
            [matDatepicker]="startDatePicker"
            [max]="form.get('stepOne.endDate').value"
            formControlName="startDate"
            matInput
            name="date">
            <mat-datepicker-toggle [for]="startDatePicker"></mat-datepicker-toggle>
            <mat-datepicker #startDatePicker></mat-datepicker>
            <mat-error *ngIf="form.get('stepOne.startDate').hasError('matDatepickerMax') || form.get('stepOne.startDate').hasError('matDatepickerMin')">
              Invalid date
            </mat-error>
        <input
            [matDatepicker]="endDatePicker"
            [min]="form.get('stepOne.startDate').value"
            formControlName="endDate"
            matInput
            name="date">
            <mat-datepicker-toggle [for]="endDatePicker"></mat-datepicker-toggle>
            <mat-datepicker #endDatePicker></mat-datepicker>
            <mat-error *ngIf="form.get('stepOne.endDate').hasError('matDatepickerMax') || form.get('stepOne.endDate').hasError('matDatepickerMin')">
              Invalid date
            </mat-error>
            <p>
            {{ form.get('stepOne.startDate').errors | json }} 
            </p>
            <p>
            {{ form.get('stepOne.endDate').errors | json }}
            </p>
            </div>
    </mat-step>
    <mat-step [stepControl]="form.get('stepTwo')">
    Test 2
    </mat-step>
  </mat-horizontal-stepper>
</form>

[patrykp57]

I've change it to this and it's working now. Probably shouldn't put formGroupName on ng-container with ngIf inside step, but didn't have time to investigate further.

<form [formGroup]="form">
<mat-horizontal-stepper [linear]="true" #stepper>
    <mat-step [stepControl]="form.get('stepOne')">
        <div [hidden]="stepper.selectedIndex !== 0" formGroupName="stepOne">
        <input
            [matDatepicker]="startDatePicker"
            [max]="form.get('stepOne.endDate').value"
            formControlName="startDate"
            matInput
            name="date">
            <mat-datepicker-toggle [for]="startDatePicker"></mat-datepicker-toggle>
            <mat-datepicker #startDatePicker></mat-datepicker>
            <mat-error *ngIf="form.get('stepOne.startDate').hasError('matDatepickerMax') || form.get('stepOne.startDate').hasError('matDatepickerMin')">
              Invalid date
            </mat-error>
        <input
            [matDatepicker]="endDatePicker"
            [min]="form.get('stepOne.startDate').value"
            formControlName="endDate"
            matInput
            name="date">
            <mat-datepicker-toggle [for]="endDatePicker"></mat-datepicker-toggle>
            <mat-datepicker #endDatePicker></mat-datepicker>
            <mat-error *ngIf="form.get('stepOne.endDate').hasError('matDatepickerMax') || form.get('stepOne.endDate').hasError('matDatepickerMin')">
              Invalid date
            </mat-error>
            <p>
            {{ form.get('stepOne.startDate').errors | json }} 
            </p>
            <p>
            {{ form.get('stepOne.endDate').errors | json }}
            </p>
            </div>
    </mat-step>
    <mat-step [stepControl]="form.get('stepTwo')">
    Test 2
    </mat-step>
  </mat-horizontal-stepper>
</form>

It doesn't change anything at all. One solution is to remove *ngIf from ng-container and everything is working well, but in my application each step depend on previous. I can't initialise all components at once.

[akvamor]

I have the similar problem with the ngFor. When I removed one of the item form the list, validation rules for the datepicker inside of ngFor will stuck with the last provided rules. When I provide new rules calendar give an ability to select new date but it is invalid. I am using CustomDateAdapater, and validation rules are coming from the outside of the ngFor block. If I removing one more item from the list it will update to the previous validation rules, but not to the actual.

[jelbourn]

@crisbeto could you look into this one? Got a couple of independent escalations related to datepicker min/max. I suspect this might be related: https://stackblitz.com/edit/angular-e2hojg-hfkdyh (unable to select a date when one of the constraints is a new instance every time)

[crisbeto]

@jelbourn this seems like a different issue from the one you linked which is the same as https://github.com/angular/components/issues/20278.