problem with basic attributes java.sql.Blob

Question

Hi every one, I have this code

@Entity
@Table(name = "picture")
public class Picture implements Serializable {
    @Id
    @Column(name = "id")
    @GeneratedValue
    private int id;
    @Column(name = "format", length = 8)
    private String format;

    @Basic(fetch = FetchType.LAZY)
    @Column(name = "context", nullable = true, columnDefinition="mediumblob")
    @Lob
    private java.sql.Blob myBlobAttribute; // protected accessor and modifier

    @ManyToOne(fetch = FetchType.EAGER)
    @JoinColumn(name = "branch_fk", referencedColumnName = "id", nullable = false)
    private Branch branch;
//Some setter and getter

I use netbeans 6.7 and in this Ide it show me error on line (private java.sql.Blob myBlobAttribute;) but code run and it's make picture table on my database! is it a real error or just e notification and how must I solve it? error message was:

basic attributes can only be of the following types: java primitive types,wrapper of primitive types, String, java.math.bigInteger, java.math.BigDecimal, java,util.Date, java.util.Calendar, java.sql.Data, java.sql.TimeStamp, byte[], Byte[], char[], Character[], enums, or any Serializable type

Answer 1

Is the problem on the line before?

@Lob

Should be @Blob maybe?

Answer 2

Your property type is java.sql.Blob which is an interface.
First of all, why? Shouldn't it be a byte array (presumably that's where you store your image)?
Secondly, that's why NetBeans complains - and so will Hibernate once you try to read stuff from this table - they have no way of knowing what actual type to create to put data in your field.

Answer 3

Hi Amirreza. The reason that NetBeans is generating this warning is that the @Basic and @Lob annotations are mutually exclusive when using java.sql.Blob, you should only have the @Lob annotation and not @Basic.

However, at runtime, it sounds like your JPA implementation is "helping you out" by ignoring the @Basic annotation and recognizing that the column is in fact a LOB. This is why your code works. It is possible that a different JPA implementation would fail or somehow behave differently.

(edited to correct my earlier statement)