How to only allow entries from autocomplete as chips?

[Alinex]

      <q-chips-input v-model="roles_chips" placeholder="Type some characters to search" 
        @duplicate="duplicate">
        <q-autocomplete @search="search" :debounce="100" />
      </q-chips-input> 

How can I prevent the user to add something which is not in the autocomplete search list?