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From "David Ciemiewicz (JIRA)" <j...@apache.org>
Subject [jira] Created: (PIG-745) Please add DataTypes.toString() conversion function
Date Wed, 01 Apr 2009 20:45:12 GMT
Please add DataTypes.toString() conversion function
---------------------------------------------------

                 Key: PIG-745
                 URL: https://issues.apache.org/jira/browse/PIG-745
             Project: Pig
          Issue Type: Improvement
            Reporter: David Ciemiewicz


I'm doing some work in string manipulation UDFs and I've found that it would be very convenient
if I could always convert the argument to a chararray (internally a Java String).

For example TOLOWERCASE(arg) shouldn't really care whether arg is a bytearray, chararray,
int, long, double, or float, it should be treated as a string and operated on.

The simplest and most foolproof method would be if the DataTypes added a static function of
 DataTypes.toString which did all of the argument type checking and provided consistent translation.

I believe that this function might be coded as:

    public static String toString(Object o) throws ExecException {
        try {
			switch (findType(o)) {
			case BOOLEAN:
			    if (((Boolean)o) == true) return new String('1');
			    else return new String('0');

			case BYTE:
			    return ((Byte)o).toString();

			case INTEGER:
			    return ((Integer)o).toString();

			case LONG:
			    return ((Long)o).toString();

			case FLOAT:
			    return ((Float)o).toString();

			case DOUBLE:
			    return ((Double)o).toString();

			case BYTEARRAY:
			    return ((DataByteArray)o).toString();

			case CHARARRAY:
		            return (String)o;

			case NULL:
			    return null;

			case MAP:
			case TUPLE:
			case BAG:
			case UNKNOWN:
			default:
			    int errCode = 1071;
			    String msg = "Cannot convert a " + findTypeName(o) +
			    " to an String";
			    throw new ExecException(msg, errCode, PigException.INPUT);
			}
		} catch (ExecException ee) {
			throw ee;
		} catch (Exception e) {
			int errCode = 2054;
			String msg = "Internal error. Could not convert " + o + " to String.";
			throw new ExecException(msg, errCode, PigException.BUG);
		}
    }



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