Cfrgtkky

I'm learning how to use Spring JPA and am have configured my database to successfully add elements to my database. I'm just having trouble formulating a query to retrieve my results (a list of Employee, filtered by lastname):

//Employee entity:

@Entity

public class Employee {



    @Id

    @GeneratedValue(strategy=GenerationType.IDENTITY)

    long id;

    String firstName;

    String lastName;



    public Employee() { }



    public Employee(long id, String firstName, String lastName) {

        super();

        this.id = id;

        this.firstName = firstName;

        this.lastName = lastName;

    }



    public long getId() {

        return id;

    }

    public void setId(long id) {

        this.id = id;

    }

    public String getFirstName() {

        return firstName;

    }

    public void setFirstName(String firstName) {

        this.firstName = firstName;

    }

    public String getLastName() {

        return lastName;

    }

    public void setLastName(String lastName) {

        this.lastName = lastName;

    }



    @Override

    public int hashCode() {

        final int prime = 31;

        int result = 1;

        result = prime * result + ((firstName == null) ? 0 : firstName.hashCode());

        result = prime * result + (int) (id ^ (id >>> 32));

        result = prime * result + ((lastName == null) ? 0 : lastName.hashCode());

        return result;

    }

    @Override

    public boolean equals(Object obj) {

        if (this == obj)

            return true;

        if (obj == null)

            return false;

        if (getClass() != obj.getClass())

            return false;

        Employee other = (Employee) obj;

        if (firstName == null) {

            if (other.firstName != null)

                return false;

        } else if (!firstName.equals(other.firstName))

            return false;

        if (id != other.id)

            return false;

        if (lastName == null) {

            if (other.lastName != null)

                return false;

        } else if (!lastName.equals(other.lastName))

            return false;

        return true;

    }



    @Override

    public String toString() {

        return "Employee [id=" + id + ", firstName=" + firstName + ", lastName=" + lastName + "]";

    }



}

And my problem is within the query in my repository interface below. When invoking the findByLastName(String lastName) method, I'm always receiving an empty Collection -- even when passing a lastName that I know exists in my database:

public interface EmployeeRepository

    extends CrudRepository<Employee, Long> {



    @Query("select u from Employee u where u.lastName = ?1")

    public Collection<Employee> findByLastName(String lastName);

}

It's also worth mentioning that the column i'm querying is named last_name in my database column (with underscores). I'm not sure if this makes any difference.

Where did I go wrong?

You need add @Column on the field to let jpa know how to create the mappings between database and java class.

For example:

@Entity

@Table(name="target_table_name")

public class Employee {



    @Id

    @GeneratedValue(strategy=GenerationType.IDENTITY)

    private long id;



    @Column(name="first_name")

    private String firstName;



    @Column(name="last_name")

    private String lastName;

    //getter and setter and something else

}

Without @Table,the entity's name will be recognized by jpa as the table name.If they are not same,you should add @Table on the class and specify the table name.

"first_name" and "last_name" in the annotation is the actual name of the database column,you should change it if necessary.

By the way,it's better to set the access of entities' fields as private.