//  <tag>
//    <name>select</name>
//    <tagclass>mytags.SelectTag</tagclass>
//    <info>
//        Do an SQL "SELECT" query, and iterate over rows of result.
//    </info>
//    <attribute>
//       <name>session</name>
//       <required>true</required>
//    </attribute>
//    <attribute>
//       <name>columns</name>
//       <required>true</required>
//    </attribute>
//    <attribute>
//       <name>table</name>
//       <required>true</required>
//    </attribute>
//    <bodycontent>JSP</bodycontent>
//  </tag>       


package mytags ;

import javax.servlet.*;
import javax.servlet.http.*;

import javax.servlet.jsp.* ;
import javax.servlet.jsp.tagext.* ;
import java.io.* ;

import java.sql.*;

public class SelectTag extends BodyTagSupport {
    public int doStartTag() throws JspException {
        try {
            HttpSession session = pageContext.getSession() ;

            DBSession dbs = (DBSession) session.getAttribute(sessionID) ;

            if(dbs == null) {
                dbs = new DBSession() ;
                session.setAttribute(sessionID, dbs) ;

                session.setMaxInactiveInterval(300) ;  // 5 minutes.
            }

            rs = dbs.stat.executeQuery("SELECT " + columns + " FROM " + table) ;

            if(rs.next())
                return EVAL_BODY_TAG ;
            else
                return SKIP_BODY ;

        } catch (SQLException e) {
            throw new JspTagException(e.getMessage()) ;
        }
    }

    public int doAfterBody() throws JspException {
        try {
            if(rs.next())
                return EVAL_BODY_TAG ;
            else {
                BodyContent body = getBodyContent() ;
                body.writeOut(getPreviousOut()) ;
        
                return SKIP_BODY ;
            }

        } catch (IOException e) {
            throw new JspTagException(e.getMessage()) ;
        } catch (SQLException e) {
            throw new JspTagException(e.getMessage()) ;
        }
    }

    public void setSession(String sessionID) {
        this.sessionID = sessionID ;
    }

    public void setTable(String table) {
        this.table = table ;
    }

    public void setColumns(String columns) {
        this.columns = columns ;
    }

    private String sessionID, columns, table ;

    ResultSet rs ;
}