Pass array from Java to Oracle: java.sql.SQLException: Fail to convert to internal representation:error

Question

I have the following in DAO and when I execute, I am getting

java.sql.SQLException: Fail to convert to internal representation: test.Project@843

DAO Code

List projectList = new LinkedList();

public void saveRecord(List<Project> project) 
                       throws DatabaseException,SQLException {

    for (Project items: project) {
        insertRecord(items);
    }
}

private void insertRecord(Project project) throws SQLException {
    projectList.add(project);
    try{
        ArrayDescriptor desc = 
                ArrayDescriptor.createDescriptor("MY_ARRAY", dbConn);

        // execpetion in this line
        ARRAY arr = new ARRAY(desc, dbConn, (Object[])projectList.toArray());

How can I resolve this issue?

Edit 1

CREATE OR REPLACE TYPE project_type as object( 
proj_id varchar2 (10),
proj_title varchar2 (10));


create or replace  type my_array as Table of project_type;

Solution 1

Unfortunately, this is more complicated than one might expect. You have to use STRUCT objects, descriptors and, finally, ARRAY. Below is a working example.

-- Database code --

CREATE TABLE project_types (
  proj_id VARCHAR2(10),
  proj_title VARCHAR2(10)
);
/

CREATE OR REPLACE TYPE project_type AS OBJECT ( 
  proj_id VARCHAR2(10),
  proj_title VARCHAR2(10)
);
/

CREATE OR REPLACE TYPE my_array AS TABLE OF project_type;
/

CREATE OR REPLACE PROCEDURE add_projects(p_projects_array IN my_array)
AS
BEGIN
  IF p_projects_array IS NOT NULL THEN
    FOR v_i IN 1..p_projects_array.LAST
    LOOP
      INSERT INTO project_types
        VALUES (p_projects_array(v_i).proj_id,
                p_projects_array(v_i).proj_title);
    END LOOP;
  END IF;
END;
/

// Java code - main class

import java.sql.Connection;
import java.sql.DriverManager;

import oracle.jdbc.OracleCallableStatement;
import oracle.jdbc.OracleConnection;
import oracle.sql.ARRAY;
import oracle.sql.ArrayDescriptor;
import oracle.sql.STRUCT;
import oracle.sql.StructDescriptor;

public class ArrayExampleMain {

  public static void main(String[] args) throws Exception {
    OracleConnection conn = getOracleConnection().unwrap(OracleConnection.class);
    System.out.println("Got Connection.");

    OracleCallableStatement callStmt = null;

    try {
      callStmt = (OracleCallableStatement)conn.prepareCall("{call add_projects(?)}");

      // create array holding values for ProjectType object's properties
      Object[] project1 = new Object[] {"1", "Title 1"};
      Object[] project2 = new Object[] {"2", "Title 2"};

      // descriptor for OBJECT type defined in database
      StructDescriptor projectTypeDesc = StructDescriptor.createDescriptor("PROJECT_TYPE", conn);

      // each struct is one ProjectType object
      STRUCT structProject1 = new STRUCT(projectTypeDesc, conn, project1);
      STRUCT structProject2 = new STRUCT(projectTypeDesc, conn, project2);

      STRUCT[] structArrayOfProjects = {structProject1, structProject2};

      // descriptor of TABLE type defined in database
      ArrayDescriptor projectTypeArrayDesc = ArrayDescriptor.createDescriptor("MY_ARRAY", conn);

      // array holding two ProjectType objects
      ARRAY arrayOfProjects = new ARRAY(projectTypeArrayDesc, conn, structArrayOfProjects);

      callStmt.setARRAY(1, arrayOfProjects); 
      callStmt.execute();
      conn.commit();

      System.out.println("Committed.");
    } catch (Exception e) {
      if (conn != null) try { conn.rollback(); } catch (Exception ex) { System.out.println("Rollback failed."); }
      throw e;
    } finally {
      callStmt.close();
      conn.close();
     }
  }

  public static Connection getOracleConnection() throws Exception {
    String driver = "oracle.jdbc.driver.OracleDriver";
    String url = "jdbc:oracle:thin:@YOUR_HOST:orcl";
    String username = "hr";
    String password = "password";

    Class.forName(driver); // load Oracle driver

    Connection conn = DriverManager.getConnection(url, username, password);

    return conn;
  }
}

Checking content of the project_types table after execution of main class:

SELECT * FROM project_types;

Output:

PROJ_ID    PROJ_TITLE
---------- ----------
1          Title 1    
2          Title 2

Solution 2

Thanks, @PrzemyslawKruglej. I took the liberty of cleaning up the deprecated classes.

import java.sql.Array;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.Struct;

import oracle.jdbc.OracleCallableStatement;
import oracle.jdbc.OracleConnection;

public class ArrayExampleMain {

  public static void main(String[] args) throws Exception {
    OracleConnection conn = getOracleConnection().unwrap(OracleConnection.class);
    System.out.println("Got Connection.");

    OracleCallableStatement callStmt = null;

    try {
      callStmt = (OracleCallableStatement)conn.prepareCall("{call add_projects(?)}");

      // create array holding values for ProjectType object's properties
      Object[] project1 = new Object[] {"1", "Title 1"};
      Object[] project2 = new Object[] {"2", "Title 2"};

      // each struct is one ProjectType object
      Struct structProject1 = conn.createStruct("PROJECT_TYPE", project1);
      Struct structProject2 = conn.createStruct("PROJECT_TYPE", project2);

      Struct[] structArrayOfProjects = {structProject1, structProject2};

      // array holding two ProjectType objects
      Array arrayOfProjects = conn.createOracleArray("MY_ARRAY", structArrayOfProjects);

      callStmt.setArray(1, arrayOfProjects); 
      callStmt.execute();
      conn.commit();

      System.out.println("Committed.");
    } catch (Exception e) {
      if (conn != null) try { conn.rollback(); } catch (Exception ex) { System.out.println("Rollback failed."); }
      throw e;
    } finally {
      callStmt.close();
      conn.close();
     }
  }

  public static Connection getOracleConnection() throws Exception {
    String driver = "oracle.jdbc.driver.OracleDriver";
    String url = "jdbc:oracle:thin:@YOUR_HOST:orcl";
    String username = "hr";
    String password = "password";

    Class.forName(driver); // load Oracle driver

    Connection conn = DriverManager.getConnection(url, username, password);

    return conn;
  }
}