Reorder mat-table rows with angular material's drag-and-drop

Question

Angular 7 brought the powerful DragDropModule with it: https://material.angular.io/cdk/drag-drop/examples

The documentation deals with rearranging items

Answer 1

I found a very good example on stackblitz: https://stackblitz.com/edit/table-drag-n-drop

To not break the ui of the Drag&Drop preview, use the tags

<mat-table>...</mat-table>
<mat-header-cell>...</mat-header-cell>
<mat-cell>...</mat-cell>
<mat-header-row>...</mat-header-row>
<mat-row>...</mat-row>

instead of

<table mat-table>...</table mat-table>
<th mat-header-cell>...</th mat-header-cell>
<td mat-cell>...</td mat-cell>
<tr mat-header-row>...</tr mat-header-row>
<tr mat-row>...</tr mat-row>

Combined with the css mentioned in https://stackoverflow.com/a/53630171/12331146 it is the perfect solution for me.

Answer 2

The styling is done by CSS (look at the CSS tab on the example page). I tweaked it to work with mat-table:

.cdk-drag-preview {
  box-sizing: border-box;
  border-radius: 4px;
  box-shadow: 0 5px 5px -3px rgba(0, 0, 0, 0.2),
              0 8px 10px 1px rgba(0, 0, 0, 0.14),
              0 3px 14px 2px rgba(0, 0, 0, 0.12);
}

.cdk-drag-placeholder {
  opacity: 0;
}

.cdk-drag-animating {
  transition: transform 250ms cubic-bezier(0, 0, 0.2, 1);
}

.cdk-drop-list-dragging .mat-row:not(.cdk-drag-placeholder) {
  transition: transform 250ms cubic-bezier(0, 0, 0.2, 1);
}

I placed this in my main styles.scss file.

---

For anyone wondering how to implement drag and drop on a mat-table, you need to:

1. Add cdkDropList to mat-table
2. Add (cdkDropListDropped)="onListDrop($event)" to mat-table
3. Add cdkDrag to mat-row

onListDrop will look something like:

onListDrop(event: CdkDragDrop<string[]>) {
  // Swap the elements around
  moveItemInArray(this.myArray, event.previousIndex, event.currentIndex);
}

moveItemInArray is an Angular Material function. You can import it.

Answer 3

If you are still using table to render a table instead of mat-table. You can consider the approach to manually set width of each td column on your table.

See the full explanation and stackblitz on https://trungk18.com/experience/angular-cdk-drag-drop-list-table/

.col-xs {
  width: 2%;
}

.col-sm {
  width: 10%;
}

.col-md {
  width: 20%;
}

<tbody cdkDropList (cdkDropListDropped)="onDrop($event)">
  <tr *ngFor="let user of users" cdkDrag cdkDragLockAxis="y">
    <th class="col-xs">
      <div class="drag-handle">
        <ng-container [ngTemplateOutlet]="dragHandleTmpl"> </ng-container>

      </div>
    </th>
    <td class="col-md"></td>
    <td class="col-md"></td>
    <td class="col-md"></td>
    <td class="col-md"></td>
  </tr>
</tbody>

This is the final result

Answer 4

I was using MatTableDataSource for my dataSource so my solution was this:

• Importing CdkDragDrop in the component and in the component.module.ts

• Adding @ViewChild('table') table: MatTable<any>; to the component.ts.

• In the HTML add:

  <table mat-table #table [dataSource]="dataSource" class="mat-elevation-z8"
    cdkDropList
    [cdkDropListData]="dataSource"
    (cdkDropListDropped)="drop($event)">
  

• At the *matRowDef you need to add this :

  <tr mat-row *matRowDef="let row; columns: displayedColumns;"
    cdkDrag 
    [cdkDragData]=row>
  </tr>
  

• Then in the component.ts I made the drop event:

  drop(event: CdkDragDrop<Scene[]>) {
    const previousIndex = this.dataSource.data.findIndex(row => row === event.item.data);
    moveItemInArray(this.dataSource.data,previousIndex, event.currentIndex);
    this.dataSource.data = this.dataSource.data.slice();
  }
  

Answer 5

Found example https://stackblitz.com/edit/angular-igmugp

Looks the missing part is

this.table.renderRows();