Delete empty row created by subscription to service on ngOnInit()

Question

I have a Material Data table, which the user can fill and empty by himself. The data, which gets into the table gets triggered by a service, which I initialized in the table component with ngOnInit().

Code:

  ngOnInit() {
    this._AS.transaction$.subscribe( transaction => {
        this.transaction = transaction;
        this.temp = this.dataSource.data.slice();
        this.temp.push(this.transaction); // Stop this call on init somehow?
        this.dataSource.data = this.temp;
        this.ref.detectChanges();
        console.log(this.transaction);
      }
    );
  }

The problem is: There is always an empty row which gets pushed by the call this.temp.push(this.transaction). Is there a way to stop this call for the first time or something similar?

Answer 1

I just used an alternative way: After pushing the empty Transaction into the table I pop it afterwards, so that the table is empty again. Pushing data works now without problems.

  ngOnInit() {
      this._AS.transaction$.subscribe(transaction => {
          this.transaction = transaction;
          this.temp = this.dataSource.data.slice();
          this.temp.push(this.transaction);
          this.dataSource.data = this.temp;
          this.ref.detectChanges();
        }
      );
      this.temp = this.dataSource.data.slice();
      this.temp.pop();
      this.dataSource.data = this.temp;
      this.ref.detectChanges();
  }