How to get cursor from Oracle using Groovy?

Question

I'm using a Groovy script in Mule ESB to get output parameters from Oracle stored procedure (including cursor) and getting an exception.

Minimal example:

import groovy.sql.Sql
import oracle.jdbc.pool.OracleDataSource
import oracle.jdbc.driver.OracleTypes

def ds = new OracleDataSource()
// setting data source parameters here

def sql = new Sql(ds)
def data = []

sql.call("""declare
result_table sys_refcursor;
begin

open result_table for select 1 as a from dual;

insert into CURSOR_TEST (ID) values (1);
commit;

${Sql.resultSet OracleTypes.CURSOR} := result_table;

insert into CURSOR_TEST (ID) values (2);
commit;

end;
"""
){ table ->

  throw new RuntimeException("Never getting this exception.")

  table.eachRow {
    data << it.toRowResult()
  }
}

sql.close()

return data

Error:

---

Message               : java.sql.SQLException: Closed Statement (javax.script.ScriptException)
Code                  : MULE_ERROR--2
--------------------------------------------------------------------------------
Exception stack is:
1. Closed Statement(SQL Code: 17009, SQL State: + 99999) (java.sql.SQLException)
  oracle.jdbc.driver.SQLStateMapping:70 (null)
2. java.sql.SQLException: Closed Statement (javax.script.ScriptException)
  org.codehaus.groovy.jsr223.GroovyScriptEngineImpl:323 (http://java.sun.com/j2ee/sdk_1.3/techdocs/api/javax/script/ScriptException.html)
3. java.sql.SQLException: Closed Statement (javax.script.ScriptException)

(org.mule.api.transformer.TransformerException) org.mule.module.scripting.transformer.ScriptTransformer:39 (http://www.mulesoft.org/docs/site/current3/apidocs/org/mule/api/transformer/TransformerException.html) -------------------------------------------------------------------------------- Root Exception stack trace: java.sql.SQLException: Closed Statement at oracle.jdbc.driver.SQLStateMapping.newSQLException(SQLStateMapping.java:70) at oracle.jdbc.driver.DatabaseError.newSQLException(DatabaseError.java:133) at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:199) + 3 more (set debug level logging or '-Dmule.verbose.exceptions=true' for everything) ********************************************************************************

Select from CURSOR_TEST returns 1 and 2.

Oracle server version: Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production.

Mule version: 3.5.0.

I'm using jdbc\lib\ojdbc6.jar from oracle client version 11.1.0.7.0.

What am I doing wrong?

Answer 1

The following code can help you get variable of SYS_REFCURSOR from Oracle anonymous block.

We should focus on a few key details:

1. Class groovy.sql.Sql doesn't have corresponding OutParameter and we make it manually as CURSOR_PARAMETER and pass it to sql.call method
2. Consider that the block starts with {call DECLARE and ends with END } without semicolon after END. Otherwise we can get a poorly recognizable SQLException in the face.
3. The question marks ? inside the sqlString are places for parameter bindings. Bindings are made in the natural order. In this example:
   • the first ? binds with the first element in parametersList: "abc", treating the value as IN parameter ;
   • the second ? binds with CURSOR_PARAMETER treating the value as OUT parameter of passed type;
4. There is only one enter into closure after sql.call and ResultSet rs provide rows of cursor my_cur declared in anonymous block.

---

import groovy.sql.OutParameter
import groovy.sql.Sql
import oracle.jdbc.OracleTypes

import java.sql.ResultSet

def driver = 'oracle.jdbc.driver.OracleDriver'
def sql = Sql.newInstance('jdbc:oracle:thin:@MY-SERVER:1521:XXX', 'usr', 'psw', driver)

// special OutParameter for cursor type
OutParameter CURSOR_PARAMETER = new OutParameter() {
    public int getType() {
        return OracleTypes.CURSOR;
    }
};

// look at some ceremonial wrappers around anonymous block
String sqlString = """{call
    DECLARE
      my_cur SYS_REFCURSOR;
      x VARCHAR2(32767) := ?;
    BEGIN

        OPEN my_cur
        FOR
        SELECT x || level AS my_column FROM dual CONNECT BY level < 10;

        ? := my_cur;
    END
}
""";

// the order of elements matches the order of bindings
def parametersList = ["abc", CURSOR_PARAMETER];


// rs contains the result set of cursor my_cur
sql.call(sqlString, parametersList) { ResultSet rs ->
  while (rs.next()) {
      println rs.getString("my_column")
  }
};