path: root/projects/net.wotonomy.persistence/src/main/java/net/wotonomy/control/PropertyDataSource.java

/*
Wotonomy: OpenStep design patterns for pure Java applications.
Copyright (C) 2000 Intersect Software Corporation

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, see http://www.gnu.org
*/

package net.wotonomy.control;

import java.lang.reflect.Array;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.TreeSet;

import net.wotonomy.foundation.NSArray;
import net.wotonomy.foundation.NSMutableArray;
import net.wotonomy.foundation.internal.Introspector;
import net.wotonomy.foundation.internal.WotonomyException;

/**
* A data source that reads and writes to an indexed 
* property of a java object. This class is used by 
* MasterDetailAssociation to retreive objects from 
* the master display group.  
*
* @author michael@mpowers.net
* @author $Author: cgruber $
* @version $Revision: 894 $
*/
public class PropertyDataSource extends OrderedDataSource
{
    protected Object source;
    protected String key;
    protected Class lastKnownType; // for best-guessing
    protected EOClassDescription classDesc;
    protected EOEditingContext context;

    /**
    * Creates a new PropertyDataSource with no editing context
    * and will try to guess the appropriate class description
    * when trying to create objects.
    */
    public PropertyDataSource()
    {
        this( null, (EOClassDescription) null );
    }
    
    /**
    * Creates a new PropertyDataSource that uses the specified
    * editing context, but will try to guess the appropriate
    * class description when trying to create objects.
    */
    public PropertyDataSource( EOEditingContext aContext )
    {
        this( aContext, (EOClassDescription) null );   
    }

    /**
    * Creates a new PropertyDataSource that uses the specified
    * editing context and vends objects of the specified class.
    */
    public PropertyDataSource( 
        EOEditingContext aContext, Class aClass )
    {
        this( aContext, EOClassDescription.classDescriptionForClass( aClass ) );
    }

    /**
    * Creates a new PropertyDataSource that uses the specified
    * editing context and vends objects of the specified
    * class description.
    */
    public PropertyDataSource( 
        EOEditingContext aContext, EOClassDescription aClassDesc )
    {
        source = null;
        key = null;
        lastKnownType = null;
        classDesc = aClassDesc;
        context = aContext;
    }
    
    /**
    * Provides the master object for detail display groups.
    */
    public Object source()
    {
        return source;
    }
    
    /**
    * Allows a detail display group to set the master object.
    */
    public void setSource( Object anObject )
    {
        source = anObject;
    }
    
    /**
    * Provides the detail key for detail display groups.
    */
    public String key()
    {
        return key;
    }

    /**
    * Allows a detail display group to set the detail key.
    */
    public void setKey( String aKey )
    {
        key = aKey;
    }

    /**
    * Inserts the specified object into this data source.
    * Calls insertObjectAtIndex and appends to the end 
    * of the list.
    */
    public void insertObject ( Object anObject )
    {
        insertObjectAtIndex( anObject, -1 ); // trick to force to end
    }

    /**
    * Inserts the specified object into this data source,
    * at the specified index.
    */
    public void insertObjectAtIndex ( 
        Object anObject, int anIndex )
    {
        if ( source == null ) return;
        List list = readAsList();
        if ( anIndex == -1 ) anIndex = list.size(); // force to end
        if ( anIndex > list.size() ) anIndex = list.size(); // force to end
        list.add( anIndex, anObject );
        writeAsList( list );
    }

    /**
    * Deletes the specified object from this data source.
    */
    public void deleteObject ( Object anObject )
    {
        if ( source == null ) return;
        List list = readAsList();
        list.remove( anObject );
        writeAsList( list );
    }

    public EOEditingContext editingContext ()
    {
        return context;
    }

    /**
    * Returns a List containing the objects in this
    * data source.  
    */
    public NSArray fetchObjects ()
    {
        if ( source == null ) return NSArray.EmptyArray;
        return readAsList(); 
    }

    /**
    * Returns a new instance of this class.
    */
    public EODataSource 
        dataSourceQualifiedByKey ( String aKey )
    {
        // determine the target class desc if possible
        EOClassDescription keyClassDesc = null;
        if ( classDesc != null )
        {
            keyClassDesc = classDesc.classDescriptionForDestinationKey( aKey );
        }
        return new PropertyDataSource( editingContext(), keyClassDesc );
    }

    /**
    * Restricts this data source to vend those 
    * objects that are associated with the specified 
    * key on the specified object.
    */
    public void 
        qualifyWithRelationshipKey ( 
        String aKey, Object anObject )
    {
        source = anObject;
        key = aKey;
    }

    /**
    * Returns the class description passed to the 
    * constructor, if any.  If no class description and
    * if the bound property is an indexed property,
    * the type of the array is returned, otherwise
    * this method returns null.  This method is called
    * by createObject().
    */
    public EOClassDescription 
        classDescriptionForObjects ()
    {
        // just return the class description if we have one
        if ( classDesc != null ) return classDesc;
        
        // otherwise, try to do some guesswork
        EOClassDescription result = null;
        
        // lastKnownType is not updated here
        Class type = lastKnownType;

        // if no last known type        
        if ( type == null )
        {
            // if source and key were specified
            if ( ( source != null ) && ( key != null ) )
            {
                // try to get an array type
                Method m = Introspector.getPropertyReadMethod(
                    source.getClass(), key, new Class[0] );
                if ( m != null )
                {
                    Class returnType = m.getReturnType();
                    if ( returnType.isArray() )
                    {
                        type = returnType.getComponentType();
                    }
                }
                else
                {
                    throw new WotonomyException( "Key does not exist for object: " + key + " : " + source );   
                }
            }
            
            // does not update lastKnownType because
            // we prefer to get that info from a fetch.
        }
        
        // if type has been determined
        if ( type != null ) 
        {
            result = 
                EOClassDescription.classDescriptionForClass( type );
        }
        
        return result;
    }
    
    /**
    * Calls getValue() and returns the result as a List.
    * Sets lastKnownType to the retrieved type.
    */
    protected NSMutableArray readAsList()
    {
        Object value = getValue();
        if ( value == null )
        {
            return new NSMutableArray();
        }
        
        Object o;
        NSMutableArray result = new NSMutableArray();
        boolean hasReadType = false;
        lastKnownType = null;
        
		// if instance of array, convert to list 
		if ( value.getClass().isArray() )
		{
			int count = Array.getLength( value );
			for ( int i = 0; i < count; i++ )
			{
                o = Array.get( value, i );
                if ( o != null )
                {
                    // we've already found a type
                    if ( hasReadType ) 
                    {
                        // check that this matches the last known type
                        if ( o.getClass() != lastKnownType )
                        {
                            // not all of the same type: set to null
                            lastKnownType = null;
                        }
                    }
                    else // this is the first type we've found
                    {
                        // remember it
                        hasReadType = true;
                        lastKnownType = o.getClass();
                    }
                }
				result.add( o );	
			}
		}
		else
		if ( value instanceof Collection )
		{
			// convert to list so we handle sets, etc.
            Iterator i = ((Collection)value).iterator();
            while ( i.hasNext() )
            {
                o = i.next();   
                if ( o != null )
                {
                    // we've already found a type
                    if ( hasReadType ) 
                    {
                        // check that this matches the last known type
                        if ( o.getClass() != lastKnownType )
                        {
                            // not all of the same type: set to null
                            lastKnownType = null;
                        }
                    }
                    else // this is the first type we've found
                    {
                        // remember it
                        hasReadType = true;
                        lastKnownType = o.getClass();
                    }
                }
                result.add( o );
            }
		}
		else
		{
            lastKnownType = null;
			throw new WotonomyException( "PropertyDataSource: " +
				"bound property was not an indexed property: " + key );
		}

        return result;
    }
    
    /**
    * Converts the specified List to lastKnownType
    * and calls setValue().
    */
    protected void writeAsList( List anObjectList )
    {
        if ( source == null )
        {
            throw new WotonomyException( "PropertyDataSource: " +
                "no source object: " + key );
        }
        
        Class c = source.getClass();
        Method m = Introspector.getPropertyReadMethod( c, key, new Class[0] );
        if ( m == null )
        {
            throw new WotonomyException( "Could not read property for object: " 
                + key + " : " + source + " (" + c + ")" );
        }

        Class returnType = m.getReturnType();

        int count = anObjectList.size();
        Object result = null;
        
        if ( returnType.isArray() )
        {
            Class type = returnType.getComponentType();
            result = Array.newInstance( type, count );
            for ( int i = 0; i < count; i++ )
            {
                Array.set( result, i, anObjectList.get( i ) );
            }
        }
        else
        {
            Collection collection = null;
            
            if ( ! returnType.isInterface() )
            {
                try
                {
                    collection = (Collection) returnType.newInstance();
                }
                catch ( Exception exc )
                {
                    // no default constructor, leave null
                }
            }
            
            // try to find an acceptable collections type
            if ( collection == null )
            {
                if ( returnType.isAssignableFrom( NSMutableArray.class ) )
                {
                    collection = new NSMutableArray();
                }
                else
                if ( returnType.isAssignableFrom( LinkedList.class ) )
                {
                    collection = new LinkedList();
                }
                else
                if ( returnType.isAssignableFrom( ArrayList.class ) )
                {
                    collection = new ArrayList();
                }
                else
                if ( returnType.isAssignableFrom( HashSet.class ) )
                {
                    collection = new HashSet();
                }
                else
                if ( returnType.isAssignableFrom( TreeSet.class ) )
                {
                    collection = new TreeSet();
                }
            }
            
            if ( collection == null )
            {
                throw new WotonomyException( "Could not create a collection of type: " + returnType );   
            }
            
            collection.addAll( anObjectList );
            result = collection;
        }
        
        setValue( result );
    }
    
    /**
    * Returns the value of the indexed property
    * specified by qualifyWithRelationshipKey.
    */
    protected Object getValue()
    {
        if ( source instanceof EOKeyValueCoding )
        {
            return ((EOKeyValueCoding)source).valueForKey( key );   
        }
        return EOKeyValueCodingSupport.valueForKey( source, key );
    }
    
    /**
    * Sets the value of the indexed property
    * specified by qualifyWithRelationshipKey.
    * The argument is assumed to be of appropriate
    * type for the property.  EOObserverCenter is
    * notified that the object will change.
    */
    protected void setValue( Object aValue )
    {
        EOClassDescription sourceDesc = 
            EOClassDescription.classDescriptionForClass( source.getClass() );
            
            
        // if we're not editing a relationship (?)
//        if ( ! sourceDesc.toManyRelationshipKeys().containsObject( key ) )
        {
            // mark the parent as changed
            EOObserverCenter.notifyObserversObjectWillChange( source );
        }

        
        if ( source instanceof EOKeyValueCoding )
        {
            ((EOKeyValueCoding)source).takeValueForKey( aValue, key );   
        }
        else
        {
            EOKeyValueCodingSupport.takeValueForKey( source, aValue, key );
        }
    }
    
}

/*
 * $Log$
 * Revision 1.2  2006/02/16 16:47:14  cgruber
 * Move some classes in to "internal" packages and re-work imports, etc.
 *
 * Also use UnsupportedOperationExceptions where appropriate, instead of WotonomyExceptions.
 *
 * Revision 1.1  2006/02/16 13:19:57  cgruber
 * Check in all sources in eclipse-friendly maven-enabled packages.
 *
 * Revision 1.14  2003/01/18 23:30:42  mpowers
 * WODisplayGroup now compiles.
 *
 * Revision 1.13  2002/10/24 21:15:36  mpowers
 * New implementations of NSArray and subclasses.
 *
 * Revision 1.12  2002/10/24 18:18:12  mpowers
 * NSArray's are now considered read-only, so we can return our internal
 * representation to reduce unnecessary object allocation.
 *
 * Revision 1.11  2002/04/15 21:55:33  mpowers
 * Catching a condition where the get may not return the value passed to set.
 *
 * Revision 1.10  2002/03/08 23:20:37  mpowers
 * insertObject now calls insertObjectAtIndex.
 *
 * Revision 1.9  2001/06/05 19:10:41  mpowers
 * Better handling of null properties.
 *
 * Revision 1.8  2001/05/21 14:03:35  mpowers
 * Added a convenience constructor for java classes.
 *
 * Revision 1.7  2001/04/30 13:15:24  mpowers
 * Child contexts re-initializing objects invalidated in parent now
 * propery transpose relationships.
 *
 * Revision 1.6  2001/04/29 02:29:31  mpowers
 * Debugging relationship faulting.
 *
 * Revision 1.5  2001/04/28 22:17:51  mpowers
 * Revised PropertyDataSource to be EOClassDescription-aware.
 *
 * Revision 1.4  2001/04/27 23:37:20  mpowers
 * Now using EOClassDescription in the EODataSource class, as we should.
 *
 * Revision 1.3  2001/03/29 03:29:49  mpowers
 * Now using KeyValueCoding and Support instead of Introspector.
 *
 * Revision 1.2  2001/01/24 14:10:53  mpowers
 * Contributing OrderedDataSource, and PropertyDataSource extends it.
 *
 * Revision 1.1.1.1  2000/12/21 15:46:50  mpowers
 * Contributing wotonomy.
 *
 * Revision 1.3  2000/12/20 16:25:35  michael
 * Added log to all files.
 *
 *
 */