From: marek at lewczuk.com (Marek Lewczuk)
Date: Thu, 18 May 2006 15:31:42 +0200
Subject: [Pljava-dev] ResultSet getString
In-Reply-To: <446C69C8.3030908@tada.se>
References: <446C5033.2000508@lewczuk.com> <446C55FE.2020902@tada.se>
	<e4hmi1$9o3$1@sea.gmane.org> <446C69C8.3030908@tada.se>
Message-ID: <446C773E.6000102@lewczuk.com>

Thomas Hallgren napisa?(a):
> Marek Lewczuk wrote:
> I see what you mean. Question is, what string representation should be 
> used? What is more intuitive? Using the Java 'toString()' representation 
> of an object or the PostgreSQL String representation of the SQL type?
> 
> A typical Java developer who's not fluent in PostgreSQL type coercion 
> would expect that ResultSet.getString() on a boolean would return "true" 
> or "false", i.e. something that can be passed to Boolean.valueOf(String) 
> and that Array types would follow the format stipulated by 
> java.util.Arrays.toString(<type>[]) family of methods.
> 
> At present, the getString() method will coerce basic types to strings 
> using Java semantics. Arrays are not coerced though, since that 
> functionality was introduced in Java 1.

Lets see what Java api say about ResultSet.getString():
"Retrieves the value of the designated column in the current row of this 
ResultSet object as a String in the Java programming language."

It doesn't say, that getString() will return "a string representation of 
the object". Now, if I would like to get PostgreSQL String 
representation of multi-dimensional array, what method should I use ? 
For me obvious thing to do is to call getString() and I wouldn't expect 
that this will return same as ResultSet.getBoolean().toString(). Another 
example:

Statement statement = ...
statement.execute()...
ResultSet result = ...
while (result.next()) {
  // result contains 3 columns: varchar[], boolean, integer[]

  // we create a duplicated row, without worrying about the SQL type
  Statement s = connection.createStatement();
  s.executeUpdate("INSERT ... (c1, c2, c3) VALUES ('" + 
result.getString(0) + "', '" + result.getString(1) + "', '" + 
result.getString(2) + "')");
}

My opinion is that you should keep getString() as a method to get 
PostgreSQL string representation - this will keep  compatibility with 
previous pljava versions.

ML