How to store file in postgres database using hibernate?

Question

I am new to Hibernate. I need to store file in postgres, data type of the column is bytea. I looked around on internet for a working demo of this case, however I couldn't find any.

Hibernate mapping :



<property name="fileData" type="binary">
   <column name="fileData" not-null="true" />
</property>

POJO :


    private byte[] fileData;
        public byte[] getFileData() {
            return fileData;
        }
        public void setFileData(byte[] fileData) {
            this.fileData = fileData;
        }

table :

    create table nmonData(id int, buildNumber int, path text, fileName text, fileData bytea);

Error :

org.hibernate.tool.schema.spi.SchemaManagementException: Schema-validation: wrong column type encountered in column [fileData] in table [nmondata]; found [bytea (Types#BINARY)], but expecting [binary(255) (Types#VARBINARY)]
    at org.hibernate.tool.schema.internal.SchemaValidatorImpl.validateColumnType(SchemaValidatorImpl.java:105)
    at org.hibernate.tool.schema.internal.SchemaValidatorImpl.validateTable(SchemaValidatorImpl.java:92)
    at org.hibernate.tool.schema.internal.SchemaValidatorImpl.doValidation(SchemaValidatorImpl.java:50)
    at org.hibernate.tool.hbm2ddl.SchemaValidator.validate(SchemaValidator.java:91)
    at org.hibernate.internal.SessionFactoryImpl.<init>(SessionFactoryImpl.java:473)
    at org.hibernate.boot.internal.SessionFactoryBuilderImpl.build(SessionFactoryBuilderImpl.java:444)
    at com.psl.perf.hibernate.util.HibernateUtil.<clinit>(HibernateUtil.java:34)
    at com.psl.perf.DAO.NmonReportFileDaoImpl.save(NmonReportFileDaoImpl.java:15)
    at com.psl.perf.service.DataService.saveNmonCSV(DataService.java:249)
    at com.psl.perf.main.Main2.main(Main2.java:8)
Jan 22, 2016 12:26:18 PM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl stop
INFO: HHH10001008: Cleaning up connection pool [jdbc:postgresql://x.x.x.x:5432/perf]
Exception in thread "main" java.lang.NullPointerException
    at com.psl.perf.DAO.NmonReportFileDaoImpl.save(NmonReportFileDaoImpl.java:17)
    at com.psl.perf.service.DataService.saveNmonCSV(DataService.java:249)
    at com.psl.perf.main.Main2.main(Main2.java:8)

can someone share working demo or link for it?

This worked for me commenting <property name="hbm2ddl.auto">validate</property> in hibernate config file did the trick for me, however I'm confuse now about what should be the data type of column and member variable in java for storing file.

bytea in PG maps to byte[] in Java. I assume you want to store the file contents and not the reference (location). Declare the object field corresponding to the column as byte[]. Convert your file to a byte[] and set it as the field value. When your save your object the file contents will be mapped to the bytea column. While reading from the database read the byte array and reconstruct the file from the byte[]. — uncaught_exception
– uncaught_exception, Commented Jan 22, 2016 at 6:34
@ShireResident I did something similar, however still getting the error. I edited the post added code snippets and error. — Ketu
– Ketu, Commented Jan 22, 2016 at 7:03
@DavidSiro NmonReportFileDaoImpl.java is just to get a session and save the object, it does nothing else. Do you still want to see the code? — Ketu
– Ketu, Commented Jan 22, 2016 at 7:21
@ketu b why is this throwing a NPE? Exception in thread "main" java.lang.NullPointerException at com.psl.perf.DAO.NmonReportFileDaoImpl.save(NmonReportFileDaoImpl.java:17) Also, what version of Hibernate / PG are you using? — uncaught_exception
– uncaught_exception, Commented Jan 22, 2016 at 7:24

uncaught_exception · Accepted Answer · 2016-01-22 07:06:04Z

3

I assume you need to store file contents into PG bytea column.

PostgreSQL DDL

CREATE TABLE data_object
(
  obj_id bigserial NOT NULL,
  obj_name character(30),
  obj_file bytea,
  CONSTRAINT data_object_pkey PRIMARY KEY (obj_id)
)

Java Object

@Entity
@Table (name = "data_object")
public class DataObject {

    @Id
    @GeneratedValue (strategy = GenerationType.IDENTITY)
    @Column(name = "obj_id")
    private Long id;

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

    @Column(name = "obj_file")
    private byte[] file;

    // getters, setters, hasCode, equals, toString

Driver Code

byte[] data = new byte[FILE_SIZE];
// read file contents into data
DataObject obj = new DataObject();
obj.setFile(data);
// save obj using your hibernate session

I am using Hibernate 4.3.7 and PG 9.4.1

answered Jan 22, 2016 at 7:06

uncaught_exception

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