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angular-material2angular6multi-select

Select All mat option and deselect All

I have scenario as below:

enter image description here

I want to achieve is:

  1. When user click on All then all options shall be selected and when user click All again then all options shall be deselcted.
  2. If All option is checked and user click any other checkbox than All then All and clicked checkbox shall be deselected.
  3. When user selects 4 options one by one then All shall be selected.

HTML file

<mat-select placeholder="User Type" formControlName="UserType" multiple>
    <mat-option *ngFor="let filters of userTypeFilters" [value]="filters.key">
          {{filters.value}}
    </mat-option>
        <mat-option #allSelected (click)="toggleAllSelection()" [value]="0">All</mat-option>
</mat-select>

TS file

this.searchUserForm = this.fb.group({
  userType: new FormControl('')
});

userTypeFilters = [
  {
    key: 1, value: 'Value 1',
  },
  {
    key: 2, value: 'Value 2',
  },
  {
    key: 3, value: 'Value 3',
  },
  {
    key: 4, value: 'Value 4',
  }
]

toggleAllSelection() {
  if (this.allSelected.selected) {
    this.searchUserForm.controls.userType
    .patchValue([...this.userTypeFilters.map(item => item.key), 0]);
  } else {
    this.searchUserForm.controls.userType.patchValue([]);
  }
}

Now, how to achieve 2nd and 3rd point

Stackblitz is: https://stackblitz.com/edit/angular-material-with-angular-v5-znfehg?file=app/app.component.html

Solution

  • Use code as below create function on click each mat-option and select()/deselect() all option:

    See stackblitz:https://stackblitz.com/edit/angular-material-with-angular-v5-jsgvx6?file=app/app.component.html

    TS:

    togglePerOne(all){ 
   if (this.allSelected.selected) {  
    this.allSelected.deselect();
    return false;
}
  if(this.searchUserForm.controls.userType.value.length==this.userTypeFilters.length)
    this.allSelected.select();

}
  toggleAllSelection() {
    if (this.allSelected.selected) {
      this.searchUserForm.controls.userType
        .patchValue([...this.userTypeFilters.map(item => item.key), 0]);
    } else {
      this.searchUserForm.controls.userType.patchValue([]);
    }
  }

    HTML:

    <form [formGroup]="searchUserForm" fxFlex fxLayout="column" autocomplete="off" style="margin: 30px">
    <mat-select placeholder="User Type" formControlName="userType" multiple>
        <mat-option *ngFor="let filters of userTypeFilters" [value]="filters.key" (click)="togglePerOne(allSelected.viewValue)">
            {{filters.value}}
        </mat-option>
        <mat-option #allSelected (click)="toggleAllSelection()" [value]="0">All</mat-option>
    </mat-select>
</form>