fix(joinCampus): working again

Fixes #86

frontend/src/components/common/CustomComponentForAPI.js

@@ -306,9 +306,9 @@ class CustomComponentForAPI extends Component {
   joinCampus(campus) {
     const { universities, countries, cities } = this.getLatestReadDataFor(["universities", "countries", "cities"]);
     let res = Object.assign({}, campus); //copy for safety
-    res.university = universities.find(univ => univ.id = campus.university);
-    res.city = cities.find(city => city.id = campus.city);
-    res.country = countries.find(country => country.id = res.city.country);
+    res.university = universities.find(univ => univ.id == campus.university);
+    res.city = cities.find(city => city.id == campus.city);
+    res.country = countries.find(country => country.id == res.city.country);
     return res;
   }