[Vuejs]-Vuetify Form Data Undefined

You should add that properties to your data object and bind them to the v-text-field as follows :

data(){
   return{
     subject:'',
     context:''
      }
    }

and bind them using v-model directive in your template fields like :

<v-text-field name="subject" v-model="subject"></v-text-field>
<v-textarea name="context" v-model="context"></v-textarea>