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com.hfg xml, html, svg, and bioinformatics utility library
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package com.hfg.sql.table.field;


import java.lang.reflect.Constructor;
import java.sql.PreparedStatement;
import java.sql.ResultSet;

import com.hfg.exception.ProgrammingException;
import com.hfg.sql.jdbc.JDBCException;
import com.hfg.sql.table.DatabaseCol;
import com.hfg.sql.table.DatabaseTable;
import com.hfg.xml.XMLTag;


//------------------------------------------------------------------------------
/**
 Base class for a database field.
 
 @author J. Alex Taylor, hairyfatguy.com
 
 */
//------------------------------------------------------------------------------
// com.hfg XML/HTML Coding Library
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
//
// J. Alex Taylor, President, Founder, CEO, COO, CFO, OOPS hairyfatguy.com
// [email protected]
//------------------------------------------------------------------------------

public abstract class DatabaseField implements Cloneable
{
   private DatabaseCol   mCol;
   private T             mValue;
   private boolean       mIsDirty;

   public static final String XML_FIELD = "Field";
   private static final String XML_CLASS_ATT = "class";
   private static final String XML_NAME_ATT = "name";
   private static final String XML_IS_NULL_ATT = "isNull";

   //###########################################################################
   // CONSTRUCTORS
   //###########################################################################

   //---------------------------------------------------------------------------
   public DatabaseField(DatabaseCol inCol, T inValue)
   {
      mCol   = inCol;
      mValue = inValue;
   }

   //---------------------------------------------------------------------------
   public DatabaseField(XMLTag inXMLTag, DatabaseTable inTable)
   {
      inXMLTag.verifyTagName(XML_FIELD);

      mCol = inTable.getCol(inXMLTag.getAttributeValue(XML_NAME_ATT));

      if (! inXMLTag.hasAttribute(XML_IS_NULL_ATT))
      {
         setValueFromString(inXMLTag.getUnescapedContent());
      }
   }

   //###########################################################################
   // PUBLIC METHODS
   //###########################################################################


   //---------------------------------------------------------------------------
   public static DatabaseField instantiate(XMLTag inXMLTag, DatabaseTable inTable)
   {
      DatabaseField field;
      try
      {
         Class clazz = Class.forName(inXMLTag.getAttributeValue(XML_CLASS_ATT));
         Constructor constructor = clazz.getConstructor(XMLTag.class, DatabaseTable.class);
         field = (DatabaseField) constructor.newInstance(inXMLTag, inTable);
      }
      catch (Exception e)
      {
         throw new JDBCException(e);
      }

      return field;
   }

   //---------------------------------------------------------------------------
   @Override
   public String toString()
   {
      return isNull() ? "null" : getValue().toString();
   }

   //---------------------------------------------------------------------------
   public XMLTag toXMLTag()
   {
      XMLTag tag = new XMLTag(XML_FIELD);

      tag.setAttribute(XML_CLASS_ATT, getClass().getName());
      tag.setAttribute(XML_NAME_ATT, getCol().name());

      if (isNull())
      {
         tag.setAttribute(XML_IS_NULL_ATT, true);
      }
      else
      {
         tag.setContent(getStringValue());
      }

      return tag;
   }

   //---------------------------------------------------------------------------
   protected String getStringValue()
   {
      return (getValue() != null ? getValue().toString() : null);
   }

   //---------------------------------------------------------------------------
   @Override
   public DatabaseField clone()
   {
      DatabaseField cloneObj;
      try
      {
         cloneObj = (DatabaseField) super.clone();
      }
      catch (CloneNotSupportedException e)
      {
         throw new ProgrammingException(e);
      }

      return cloneObj;
   }

   //---------------------------------------------------------------------------
   public DatabaseCol getCol()
   {
      return mCol;
   }

   //---------------------------------------------------------------------------
   public abstract void setValueFromResultSet(ResultSet inResultSet);

   //---------------------------------------------------------------------------
   public abstract void setValueInPreparedStatement(PreparedStatement inPreparedStatement, int inIndex);

   //---------------------------------------------------------------------------
   public abstract void setValueFromString(String inValue);

   //---------------------------------------------------------------------------
   public void setValue(T inValue)
   {
      if ((null == inValue
           && mValue != null)
          || (inValue != null
              && ! inValue.equals(mValue)))
      {
         mIsDirty = true;
      }

      mValue = inValue;
   }

   //---------------------------------------------------------------------------
   public T getValue()
   {
      return mValue;
   }

   //---------------------------------------------------------------------------
   public String getSQLValue()
   {
      return mValue != null ? mValue.toString() : "null";
   }

   //---------------------------------------------------------------------------
   public boolean isNull()
   {
      return null == mValue;
   }

   //---------------------------------------------------------------------------
   public boolean isDirty()
   {
      return mIsDirty;
   }

   //---------------------------------------------------------------------------
   public DatabaseField setIsDirty(boolean inValue)
   {
      mIsDirty = inValue;
      return this;
   }

}