Angular 2 multiple checkboxes value

I have this code which generates multiple checkboxes from database:

<div *ngIf="edit">
<div class="checkbox" *ngFor="let contactType of contactTypes">
    <label class="filled">
    <input                                  
        type="checkbox"
        formControlName="types"
        name="types"
        value=""                                                                  
        > 
        
    </label>
</div>

I need to submit all values from checked check-boxes, and store the value in object property as a string, with values delimited by comma. How can I do this? Please have in mind that I'm pretty new to Angular.