@Query 与预期类型不匹配 [java.util.Collection (n/a)]

Question

I have a table named Tasks with following columns in it: author, responsible and observers all of them are FKs of user ids which are located in Users table. And I have the table representing many-to-many relation between Users and Tasks which contains only two columns: task_id and user_id. I am using @Query from Spring boot to select all the rows from Tasks. My issue is that I want to select all the tasks in which currently authorized user is being observer.

My task model:

@Entity
@Table
public class Task {

private String title;

private String description;

@Column(name = "delete_status")
private Boolean deleteStatus;

@OneToOne
@JoinColumn(name = "task_status_id")
private TaskStatus status;

@OneToMany(mappedBy = "task")
@LazyCollection(LazyCollectionOption.FALSE)
private List<Comment> comments;

@JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "yyyy-MM-dd HH:mm:ss")
@Column(name = "due_date")
private Date dueDate;

@ManyToOne
@JoinColumn(name = "author_id", updatable = false)
private User author;

@ManyToOne
@JoinColumn(name = "responsible_id")
private User responsible;

@JsonManagedReference
@ManyToMany(cascade = CascadeType.ALL)
@JoinTable(name = "observers_users",
        joinColumns = {@JoinColumn(name = "observers_id", referencedColumnName = "id")},
        inverseJoinColumns = {@JoinColumn(name = "users_id", referencedColumnName = "id")})
@LazyCollection(LazyCollectionOption.FALSE)
private List<User> observers;
}

My query:

@Query("FROM Task t WHERE t.observers = ?1 ORDER BY t.id DESC")
List<Task> findWhereUserObserver(
        @Param("observers") List<User> user
);

No matter how I change the query, I keep getting the same error: Parameter value [User (...)] did not match expected type [java.util.Collection (n / a)]

Because t.observers is type of List I can't figure out how to use it within SQL query in WHERE condition. I want to find my currently authorized user in this list but don't understand how should I do so in SQL query. Or should I at all?

Answer 1

Well when you say sth. like T.OBSERVERS IN it means that you will have more than one observer in a list such as IN (User1, User2, User3) etc. But you only have 1 User. Checkout SQL IN statement https://www.w3schools.com/sql/sql_in.asp