Filtering specific column in Angular Material Table with filtering in angular?

Question

I am using mat-table. It has a filter which works fine.

Filter happened against this below data (All columns)

const ELEMENT_DATA: Element[] = [
  {position: 14598, name: 'Hydrogen', weight: 1.0079, symbol: 'H'},
  {position: 24220, name: 'Helium', weight: 4.0026, symbol: 'He'},
  {position: 39635, name: 'Lithium', weight: 6.941, symbol: 'Li'},
  {position: 42027, name: 'Beryllium', weight: 9.0122, symbol: 'Be'},
  {position: 53216, name: 'Boron', weight: 10.811, symbol: 'B'},
  {position: 60987, name: 'Carbon', weight: 12.0107, symbol: 'C'},
  {position: 70976, name: 'Nitrogen', weight: 14.0067, symbol: 'N'},
  {position: 81297, name: 'Oxygen', weight: 15.9994, symbol: 'O'},
  {position: 90975, name: 'Fluorine', weight: 18.9984, symbol: 'F'},
  {position: 18879, name: 'Neon', weight: 20.1797, symbol: 'Ne'},
  {position: 11209, name: 'Sodium', weight: 22.9897, symbol: 'Na'}

];

But Now I am trying to change the filter because I want is filter just for "position", "name", "symbol" column. I have gone through this example but Filtering specific column in Angular Material table in angular 5.

I did not understand please help me on this

StackBlitz Code

Answer 1

You have to override the filterPredicate of your dataSource.

Here's an example of how to do it: Working demo

---

Essentially, you want to specify what properties in your data the filter is applied to:

this.dataSource.filterPredicate = function(data, filter: string): boolean {
    return data.name.toLowerCase().includes(filter) || data.symbol.toLowerCase().includes(filter) || data.position.toString().includes(filter);
};

Answer 2

Adding to bugs' answer. Here's a more elaborate implementation,

export class FilterTable implements AfterViewInit {
  //some datasource
  datasource //=
  displayedColumns //=insert column names on which you want to filter whether they are displayed or not, but present in the datasource

  // Apply filter to the datasource
  applyFilter(filterValue: string) {
    this.datasource.filter = filterValue;
  }


  ngAfterViewInit() {
    // Overwriting filterPredicate here, as it needs to be done after the datasource is loaded.
    this.datasource.filterPredicate = (data, filter) => {
      var tot = false;
      for (let column of this.displayedColumns) {
        //incase if there is a date type and is displayed differently using a pipe, then convert it intorequired format before filtering
        //check if all the columnson which you are filtering are actually present
        if ((column in data) && (new Date(data[column].toString()).toString() == "Invalid Date")) {
          //if not date column
          tot = (tot || data[column].toString().trim().toLowerCase().indexOf(filter.trim().toLowerCase()) !== -1);
        } else {
          //change this to the format in which date is displayed
          var date = new Date(data[column].toString());
          var m = date.toDateString().slice(4, 7) + " " + date.getDate() + " " + date.getFullYear();
          tot = (tot || m.toLowerCase().indexOf(filter.trim().toLowerCase()) !== -1);
        }
      }
      return tot;
    }
  }
}

Please feel free to suggest edits, if this could be improved