title: Angular - How to set selected values for a mat-select from a datasource of a dynamic sized table
body: <p>I am setting up a mat-table that shows some values from a datasource and has a mat-select with multiple select in each row. The datasource for the table is an array of objects("CarManufacturer"), that holds another array of objects("Brand"). In the mat-select I show a complete list of all "Brands".</p>
  
  <p>At the moment I cant de-/select those "Brands". They are marked as selected or not. I am not able to change this.</p>
  
  <p>I have created a function that returns an array of number(ids of brands), which feeds [value] of mat-select. That marks brands in the dropdown which are in the array of CarManufactors, but I cannot select anything in the dropdown.</p>
  
  <p>Code: <a href="https://stackblitz.com/edit/angular-skrrhb" rel="nofollow noreferrer">https://stackblitz.com/edit/angular-skrrhb</a></p>
  
  <p>I expect that I can change the values of the dropdown. At the moment I cannot de-/select the values.</p>