Using Genero records

When passing a RECORD to a Java method, the runtime system converts the RECORD to an instance of the com.fourjs.fgl.lang.FglRecord class implemented in $FGLDIR/lib/fgl.jar.

The FglRecord object is a copy of the RECORD variable; structure and members of the FglRecord object can be read within the Java code, but cannot be modified.

You must add $FGLDIR/lib/fgl.jar to the class path in order to compile Java code with com.fourjs.fgl.lang.FglRecord class.

The com.fourjs.fgl.lang.FglRecord class implements the following methods:

Table 1. Methods of the com.fourjs.fgl.lang.FglRecord class
Method	Description
`void dispose()`	Dereferences the underlaying member variables.
`double getDouble(int p)`	Returns the double value of the record member at position p.
`FglByteBlob getFglByteBlob(int p)`	Returns the `FglByteBlob` value of the record member at position p.
`FglDate getFglDate(int p)`	Returns the `FglDate` value of the record member at position p.
`FglDateTime getFglDateTime(int p)`	Returns the `FglDateTime` value of the record member at position p.
`FglDecimal getFglDecimal(int p)`	Returns the `FglDecimal` value of the record member at position p.
`FglInterval getFglInterval(int p)`	Returns the `FglInterval` value of the record member at position p.
`FglTextBlob getFglTextBlob(int p)`	Returns the `FglTextBlob` value of the record member at position p.
`int getFieldCount()`	Returns the number of record members.
`java.lang.String getFieldName(int p)`	Returns the name of the record member at position p.
`int getInt(int p)`	Returns the int value of the record member at position p.
`java.lang.String getString(int p)`	Returns the String representation of the value of the record member at position p.
`FglTypes getType(int p)`	Returns the `FglTypes` constant of the record member at position p.
`java.lang.String getTypeName(int p)`	Returns the string representation of the data type of the record member at position p.
`int getTypeQualifier(int p)`	Returns the encoded type qualifier of the record member at position p.

In the Java code, use the query methods of the com.fourjs.fgl.lang.FglRecord to identify the members of the RECORD:

public static void showMemberTypes(FglRecord rec){
    int i;
    int n = rec.getFieldCount();
    for (i = 1; i <= n; i++)
        System.out.println( String.valueOf(i) + ":" +
        rec.getFieldName(i) + " / " + rec.getTypeName(i) );
}

When assigning a RECORD to a com.fourjs.fgl.lang.FglRecord, widening conversion applies implicitly. But when assigning a com.fourjs.fgl.lang.FglRecord to a RECORD, narrowing conversion applies and you must explicitly CAST the original object reference to the type of the RECORD. The following example shows how to return an FglRecord object from a Java method:

The PassRecord.4gl source:

IMPORT JAVA com.fourjs.fgl.lang.FglRecord
IMPORT JAVA UseRecord
MAIN
    TYPE type1 RECORD
               id INTEGER,
               name VARCHAR(50)
           END RECORD
    DEFINE rec1, rec2 type1
    LET rec1.id = 123
    LET rec1.name = "McFly"
    LET rec2 = CAST(UseRecord.getRecord(rec1) AS type1)
END MAIN

The UseRecord.java source:

import com.fourjs.fgl.lang.FglRecord;
public class UseRecord{
    public static FglRecord getRecord(FglRecord rec){
        ...
        return rec;
    }
}