Issue with Material Sort functionality when null objects are present

Question

Issue with Material Sort functionality when null objects are present

I've encountered an issue with my code. I created a feature that adds empty rows if there are less than 5 rows, but now the sort function is no longer functioning properly. Strangely, when I remove the for loop responsible for adding empty rows, the sorting starts working again. Is there any solution to resolve this problem?

        this.userData = data.info;
        //when i remove this if condition the sorting works
        if(this.userData.length <=5){
          for (let index = 0; index <= 6 - this.userData.length; index++) {
              this.userData.push(Object.create(null));
          }
        }
        this.dataSource = new MatTableDataSource(this.userData);
        this.dataSource.sort = this.sort;
        this.dataSource.paginator = this.paginator;

I'm currently stuck as I really need the table to include empty rows. Any assistance would be greatly appreciated.

angular typescript angular-material2

Answer 1

Answer №1

To improve efficiency, consider replacing the if and for loop with a more streamlined while loop:

while(this.userData.length <= 5){
   this.userData.push(Object.create(null));
}

Prior to integrating the data into MatTableDataSource, it is advisable to arrange the data in the 'userData' Object according to the 'name' property. This sort function places null objects at the end of the list.

this.userData.sort((a,b) => (b.name) ? ((a.name > b.name) ? 1 : ((b.name > a.name) ? -1 : 0)) : -1);

If you wish to allow users to customize the sorting, bind to the matSortChange event on your mat-table component.

<mat-table (matSortChange)="onSortChange($event)">

Every time this event is triggered, re-sort the data accordingly.

onSortChange(sort: MatSort): void {
   const data: Array<UserData> = this.dataSource.data.slice();
   if (!sort.active || sort.direction === '') {
      this.dataSource.data = data;
      return;
   }

   this.dataSource.data = data.sort((a, b) => {
      let isAsc: boolean = sort.direction === 'asc';
      let valSortProperty = sort.active;
      return b[valSortProperty] ? this.compare(a[valSortProperty], b[valSortProperty], isAsc) : -1;
   });

   this.dataSource = new MatTableDataSource<UserData>(this.dataSource.data);
   this.dataSource.paginator = this.paginator;
}

compare(a: any, b: any, isAsc: boolean): number {
   if(isAsc){
      return (a > b) ? 1 : ((b > a) ? -1 : 0)
   } else {
      return (a < b) ? 1 : ((b < a) ? -1 : 0)
   }
}

Answer 2

To improve efficiency, consider replacing the if and for loop with a more streamlined while loop:

while(this.userData.length <= 5){
   this.userData.push(Object.create(null));
}

Prior to integrating the data into MatTableDataSource, it is advisable to arrange the data in the 'userData' Object according to the 'name' property. This sort function places null objects at the end of the list.

this.userData.sort((a,b) => (b.name) ? ((a.name > b.name) ? 1 : ((b.name > a.name) ? -1 : 0)) : -1);

If you wish to allow users to customize the sorting, bind to the matSortChange event on your mat-table component.

<mat-table (matSortChange)="onSortChange($event)">

Every time this event is triggered, re-sort the data accordingly.

onSortChange(sort: MatSort): void {
   const data: Array<UserData> = this.dataSource.data.slice();
   if (!sort.active || sort.direction === '') {
      this.dataSource.data = data;
      return;
   }

   this.dataSource.data = data.sort((a, b) => {
      let isAsc: boolean = sort.direction === 'asc';
      let valSortProperty = sort.active;
      return b[valSortProperty] ? this.compare(a[valSortProperty], b[valSortProperty], isAsc) : -1;
   });

   this.dataSource = new MatTableDataSource<UserData>(this.dataSource.data);
   this.dataSource.paginator = this.paginator;
}

compare(a: any, b: any, isAsc: boolean): number {
   if(isAsc){
      return (a > b) ? 1 : ((b > a) ? -1 : 0)
   } else {
      return (a < b) ? 1 : ((b < a) ? -1 : 0)
   }
}

Issue with Material Sort functionality when null objects are present

Answer №1

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