How to write a java.sql.Array to a java.sql.SQLOutput within SQLData.writeSQL() for Oracle

Question

I have implemented `java.sql.SQLData` in order to bind UDT objects to prepared statements using ojdbc6. Now, some of my UDT's contain arrays. What I need to do now is this: ``` class MyType implements SQLData { public void writeSQL(SQLOutput stream) throws SQLException { Array array = //... stream.writeArray(array); } } ``` In order to construct Oracle arrays, I need a JDBC Connection. Typically, this is done as such: ``` OracleConnection conn = // ... Array array = conn.createARRAY("MY_ARRAY_TYPE", new Integer[] { 1, 2, 3 }); ``` However, in that `writeSQL(SQLOutput)` method, I do not have a connection. Also, for reasons that are hard to explain in a concise question, I cannot maintain a connection reference in `MyType`. Can I somehow extract that connection from `SQLOutput`? I'd like to avoid using instable constructs like this: ``` // In ojdbc6, I have observed a private "conn" member in OracleSQLOutput: Field field = stream.getClass().getDeclaredField("conn"); field.setAccessible(…

Accepted Answer

Here's what I did to workaround this issue. It's not pretty, but it works.

I added a method in my class implementing `SQLData` that receives a `java.sql.Connection` and setups the corresponding `java.sql.ARRAY` objects.

Something like this:

```
public class MyObject01 implements SQLData {
   private String value;
   private MyObject02[] details; // do note that details is a java array
   // ... also added getters and setters for these two properties

private Array detailsArray;

public void setupArrays(oracle.jdbc.OracleConnection oconn)
      throws SQLException
   {
       detailsArrays = oconn.createARRAY(MyObject02.ORACLE_OBJECT_ARRAY_NAME, getDetails());
       // MyObject02.ORACLE_OBJECT_ARRAY_NAME must be the name of the oracle "table of" type name
       // Also note that in Oracle you can't use JDBC's default createArray
       // since it's not supported. That's why you need to get a OracleConnection
       // instance here. 
   }

@Override
   public void writeSQL(Stream stream) throws SQLException {
       stream.writeString(getValue());
       stream.writeArray(detailsArray); // that's it
   }

@Override
   public void readSQL(Stream stream) throws SQLException {
       setValue(stream.readString());
       Array array = stream.readArray();
       if (array != null) {
           setDetails((MyObject02[])array.getArray());
       }
   }
```

That's the first part.

Then, BEFORE using that object in a procedure call, invoke `setupArrays` method on that object. Example:

```
public class DB {
    public static String executeProc(Connection conn, MyObject01 obj)
        throws SQLException
    {
        CalllableStatement cs = conn.prepareCall(" { ? = call sch.proc(?) }");
        cs.registerOutParameter(1, Types.VARCHAR);
        obj.setupArrays((oracle.jdbc.Connection)conn);
        cs.setObject(2, obj, Types.STRUCT);
        cs.executeUpdate();
        String ret = cs.getString(1);
        cs.close();
        return ret;
    }
}
```

Of course, upon connection, you need to register your types properly:

```
Connection conn = DriverManager.getConnection("jdbc:oracle://localhost:1521/XE", "scott", "tiger" );
conn.getTypeMap().put(MyObject01.ORACLE_OBJECT_NAME, MyObject01.class);
conn.getTypeMap().put(MyObject02.ORACLE_OBJECT_NAME, MyObject02.class);
conn.getTypeMap().put(MyObject02.ORACLE_OBJECT_ARRAY_NAME, MyObject02[].class);
```

Hope it helps.

How to write a java.sql.Array to a java.sql.SQLOutput within SQLData.writeSQL() for Oracle

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