Why can't i reach data after Vue-Router params? - vuejs2

Question

When i search jobs and go to the details (to another page) i can't reach any results.
i think i need vuex-store but i dont understand that property.
this is jobs detail page (and value in json's)
export default {
data() {
return {
positionName: this.$route.params.positionName,
id: this.$route.params.jobId,
items: []
};
},
created() {
this.$http
.get(
"http://www.json-generator.com/api/json/get/cqdiacEgfC?indent=2" +
this.positionName +
this.id
)
.then(function(data) {
this.items = data.body;
});
}
};
<div>
<div class="card-body"
v-for="item in items"
:key="item.id">
<h5 class="card-title">{{positionName}}</h5>
<p class="card-text">{{item.companyName}}</p>
<p class="card-text">{{item.description}}</p>
<p class="card-text">{{item.countryName}}</p>
<p class="card-text">{{item.cityName}}</p>
<p class="card-text">{{item.address}}</p>
<p class="card-text">0{{item.contactPhone.areaCode}}-{{item.contactPhone.number}}</p>
<input type="button"
value="Başvur!"
class="btn btn-danger">
</div>
</div>
this is router page
import Vue from "vue";
import Router from "vue-router";
import Hey from "./components/hey.vue"
import Search from "./components/search.vue"
Vue.use(Router);
export default new Router({
mode: "history",
base: process.env.BASE_URL,
routes: [
{
path: "/",
name: "Home",
component: Search
},
{
path: "/:positionName/:jobId",
name: "JobDetail",
component: Hey
}
]
});
What can i do know? Why can't i reach json value in another page after router?