method in ArangoRepository extension class using COLLECT in query annotation to group by and count not working - spring-data

Question

I have a simple node like this below
#Document("users")
public class User {
#Id // db document field: _key
private String id;
#ArangoId // db document field: _id
private String arangoId;
private String firstName;
private String lastName;
private String country;
public User() {
super();
}
public User(String id) {
this.id = id;
}
public User(String id, String country) {
this.id = id;
this.country = country;
}
// getter & setter
#Override
public String toString() {
return "User [id=" + id + ", name=" + firstName + ", surname=" + lastName + "]";
}
public String getId() {
return id;
}
}
here is the repository class but the method getListOfCountryAndNumUsers returns null even though i have inserted users with different countries into the database.
public interface UserRepository extends ArangoRepository<User, String> {
#Query("FOR u IN users COLLECT country = u.country WITH COUNT INTO length RETURN
{\"country\" : country, \"count\" : length }")
Iterable<CountryAndNumUsers> getListOfCountryAndNumUsers();
}
I think the problem could be with the the syntax of my query in the query annotation. I didnt see any direct example of using collect operation in the spring data arango db part of arangodb documentation here but I saw the collect operation in the section "high level operations" of arangoDb documentation here
Please Help. Thanks. !

Answer 1

So I discovered my error. It was in a class I didn't add in the question. That is the class for the return object of the method getListOfCountryAndNumUsers()
i.e class CountryAndNumUsers.
public class CountryAndNumUsers {
private String country;
private Integer numberOfUsers;
public CountryAndNumUsers(String country, Integer numberOfUsers) {
this.country = country;
this.numberOfUsers = numberOfUsers;
}
public String getCountry() {
return country;
}
public Integer getNumberOfUsers() {
return numberOfUsers;
}
}
so there was a mapping mismatch since the query returns an object with different field names. I changed the query to this below so that it matches
#Query("FOR u IN users COLLECT country = u.country WITH COUNT INTO length RETURN {\"country\" : country, \"numberOfUsers\" : length }")