[SOLVED] Problem with saving data from a html form (using Thymeleaf) that has a foreign key relation between two table with Spring and JPA annotations

Problem with saving data from a html form (using Thymeleaf) that has a foreign key relation between two table with Spring and JPA annotations

I'm new with Spring development and I'm trying to understand how the relation annotations work. I have two entity, User and Country. User has a @ManyToOne relation with Country.

User Entity

@Entity
@Table(name = "user")
public class User {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "user_id")
    private int id;

    @Column(name = "name")
    private String name;

    @ManyToOne
    @JoinColumn(name = "country", foreignKey = @ForeignKey(name = "FK_country"), referencedColumnName = "name")
    private Country country;
    //Other columns, Constructor, Getter, Setter omitted
}

Country Entity

@Entity
public class Country {

    @Id
    @Column(nullable=false)
    private String name;

    @Column(nullable=false)
    private String continent;
    //Other columns, Constructor, Getter, Setter omitted
}

It creates everything as I want in the database but my problem is when I'm trying to save the data from a form. My form is taking as input a name and a selection between all the possible countries (previously loaded with a query). Once the name is provided and the country is selected, a row with name and a the id of the country should be written in my MySQL database. I'm getting the following error:

java.lang.IllegalArgumentException: Parameter value [Spain] did not match expected type [com.model.Country(n/a)]

This is because it requires a Country type but I truly need to add a row with the name and the id associated to Spain. I don't need to create the whole Country object. I don't know what to do and if I'm doing correctly. Can someone help me out, please? Thanks in advance.

Solution

You need to save the Country class object instead of just country's name, As i could see that Country class is mapped with your User class.
For that fetch the Country Class object from the name/id of the country which you're receiving from your HTML and then save it along with your User details.

Something like this :-

User user =  getUserById(user_id); //get user's details or create a new User's Object

Country country = getCountryById(country_id); //get Country's object using id or name you're receiving from your HTML-form

user.setCountry(country); //set Country's object in your User's object 

//save user's object