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JPA: how do I persist a String into a database field, type MYSQL Text

开发者 https://www.devze.com 2023-01-19 07:15 出处:网络
The requirement is that the user can write an article, therefore I choose type Text for the content field inside mysql database. How can I convert Java String into MySQL Text

The requirement is that the user can write an article, therefore I choose type Text for the content field inside mysql database. How can I convert Java String into MySQL Text

Here you go Jim Tough

@Entity
public class Article implements Serializable {
    private static final long serialVersionUID = 1L;
    @Id
    @GeneratedValue(strategy = Generati开发者_JS百科onType.AUTO)
    private Long id;

    private Long userId;

    private String title;

    private String content;

    private Integer vote;

    //Constructors, setters, getters, equals and hashcode
}

In my MYSQL database, content is type Text. I was hoping that there would be something like this java.sql.Text, since java.sql.Blob is an actual type, but sadly, that does not exist


Since you're using JPA, use the Lob annotation (and optionally the Column annotation). Here is what the JPA specification says about it:

9.1.19 Lob Annotation

A Lob annotation specifies that a persistent property or field should be persisted as a large object to a database-supported large object type. Portable applications should use the Lob annotation when mapping to a database Lob type. The Lob annotation may be used in conjunction with the Basic annotation. A Lob may be either a binary or character type. The Lob type is inferred from the type of the persistent field or property, and except for string and character-based types defaults to Blob.

So declare something like this:

@Lob 
@Column(name="CONTENT", length=512)
private String content;

References

  • JPA 1.0 specification:
    • Section 9.1.19 "Lob Annotation"


With @Lob I always end up with a LONGTEXTin MySQL.

To get TEXT I declare it that way (JPA 2.0):

@Column(columnDefinition = "TEXT")
private String text

Find this better, because I can directly choose which Text-Type the column will have in database.

For columnDefinition it is also good to read this.

EDIT: Please pay attention to Adam Siemions comment and check the database engine you are using, before applying columnDefinition = "TEXT".


for mysql 'text':

@Column(columnDefinition = "TEXT")
private String description;

for mysql 'longtext':

@Lob
private String description;
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