RE: [ANN] ExistsInRelationshipQualifier: WHERE EXISTS (SELECT 1 FROM A WHERE ...)
RE: [ANN] ExistsInRelationshipQualifier: WHERE EXISTS (SELECT 1 FROM A WHERE ...)
- Subject: RE: [ANN] ExistsInRelationshipQualifier: WHERE EXISTS (SELECT 1 FROM A WHERE ...)
- From: <email@hidden>
- Date: Mon, 28 Feb 2005 09:22:11 +0100
- Thread-topic: [ANN] ExistsInRelationshipQualifier: WHERE EXISTS (SELECT 1 FROM A WHERE ...)
Hi!
An enhanced version of QualifierGenerationSupport with the dependancy on QualifierUtilities removed looks like below.
Pierre Bernard
package my.access;
import java.lang.ref.WeakReference;
import java.lang.reflect.Constructor;
import java.util.StringTokenizer;
import java.util.WeakHashMap;
import org.apache.xerces.impl.xpath.regex.Match;
import org.apache.xerces.impl.xpath.regex.RegularExpression;
import com.webobjects.eoaccess.EOAdaptor;
import com.webobjects.eoaccess.EOAttribute;
import com.webobjects.eoaccess.EOEntity;
import com.webobjects.eoaccess.EOJoin;
import com.webobjects.eoaccess.EOQualifierSQLGeneration;
import com.webobjects.eoaccess.EORelationship;
import com.webobjects.eoaccess.EOSQLExpression;
import com.webobjects.foundation.NSArray;
import com.webobjects.foundation.NSForwardException;
import com.webobjects.foundation.NSKeyValueCodingAdditions;
import com.webobjects.foundation.NSMutableDictionary;
import my.control.Qualifier;
/** Support methods for SQL generation
*
* @author bernard
*/
public abstract class QualifierGenerationSupport extends EOQualifierSQLGeneration.Support
{
// Protected class variables
protected static WeakHashMap prefixesByExpression;
protected static String[] prefixes;
protected static WeakReference[] locks;
// Static initializer
static {
char start = 'A', end = 'Z';
int count = end - start;
int offset = 0;
QualifierGenerationSupport.prefixes = new String[count];
for (int i = 0; i < count; i++)
{
char prefix = (char) (start + i);
if (prefix == 'T')
{
offset += 1;
}
else
{
QualifierGenerationSupport.prefixes[i] = new Character(prefix).toString();
}
}
QualifierGenerationSupport.locks = new WeakReference[count - offset];
QualifierGenerationSupport.prefixesByExpression = new WeakHashMap(count - offset);
}
// Protected instance methods
protected EOAttribute attributeForPath(EOEntity entity, String keyPath)
{
if (keyPath != null)
{
StringTokenizer tokenizer =
new StringTokenizer(keyPath, NSKeyValueCodingAdditions.KeyPathSeparator);
EORelationship relationship = null;
while (tokenizer.hasMoreElements())
{
String key = tokenizer.nextToken();
if (tokenizer.hasMoreElements())
{
relationship = entity.anyRelationshipNamed(key);
}
else
{
return entity.anyAttributeNamed(key);
}
if (relationship != null)
{
entity = relationship.destinationEntity();
}
else
{
return null;
}
}
return null;
}
return null;
}
protected EORelationship relationshipForPath(EOEntity entity, String keyPath)
{
if (keyPath != null)
{
StringTokenizer tokenizer =
new StringTokenizer(keyPath, NSKeyValueCodingAdditions.KeyPathSeparator);
EORelationship relationship = null;
while (tokenizer.hasMoreElements())
{
String key = tokenizer.nextToken();
relationship = entity.anyRelationshipNamed(key);
if (relationship != null)
{
entity = relationship.destinationEntity();
}
else
{
return null;
}
}
return relationship;
}
return null;
}
protected String optimizeQualifierKeyPath(
EOEntity entity,
String keyPath,
String attributeName)
{
if ((keyPath == null) || (keyPath.length() == 0))
{
return attributeName;
}
else
{
EORelationship relationship =
(entity == null) ? null : relationshipForPath(entity, keyPath);
if (relationship != null)
{
NSArray joins = relationship.joins();
int joinCount = (joins == null) ? 0 : joins.count();
for (int i = joinCount - 1; i >= 0; i--)
{
EOJoin join = (EOJoin) joins.objectAtIndex(i);
if (join.destinationAttribute().name().equals(attributeName))
{
String newPath = Qualifier.allButLastPathComponent(keyPath);
String newAttributeName = join.sourceAttribute().name();
return optimizeQualifierKeyPath(entity, newPath, newAttributeName);
}
}
}
return (keyPath + Qualifier.KEY_PATH_SEPARATOR + attributeName);
}
}
protected String translateKeyAcrossRelationshipPath(
String keyPath,
String relationshipPath,
EOEntity entity)
{
String flattenedKeyPath = flattenRelationshipPath(keyPath, entity);
String flattenedRelationshipPath = flattenRelationshipPath(relationshipPath, entity);
String translationPath = flattenedRelationshipPath + Qualifier.KEY_PATH_SEPARATOR;
if (flattenedKeyPath.startsWith(translationPath))
{
String translatedKeyPath = flattenedKeyPath.substring(translationPath.length());
EOEntity destinationEntity =
relationshipForPath(entity, flattenedRelationshipPath).destinationEntity();
return optimizeQualifierKeyPath(
destinationEntity,
Qualifier.allButLastPathComponent(translatedKeyPath),
Qualifier.lastPathComponent(translatedKeyPath));
}
else
{
StringTokenizer tokenizer =
new StringTokenizer(flattenedRelationshipPath, Qualifier.KEY_PATH_SEPARATOR);
EOEntity tmpEntity = entity;
StringBuffer invertedRelationshipPath = new StringBuffer(flattenedKeyPath.length());
while (tokenizer.hasMoreElements())
{
String relationshipName = tokenizer.nextToken();
EORelationship relationship = tmpEntity.anyRelationshipNamed(relationshipName);
try
{
if (invertedRelationshipPath.length() > 0)
{
invertedRelationshipPath.insert(0, Qualifier.KEY_PATH_SEPARATOR_CHAR);
}
invertedRelationshipPath.insert(
0,
relationship.anyInverseRelationship().name());
}
catch (Exception exception)
{
throw new NSForwardException(exception);
}
tmpEntity = relationship.destinationEntity();
}
if (flattenedKeyPath.indexOf(Qualifier.KEY_PATH_SEPARATOR_CHAR) >= 0)
{
invertedRelationshipPath.append(Qualifier.KEY_PATH_SEPARATOR_CHAR);
invertedRelationshipPath.append(
Qualifier.allButLastPathComponent(flattenedKeyPath));
}
return optimizeQualifierKeyPath(
tmpEntity,
invertedRelationshipPath.toString(),
Qualifier.lastPathComponent(flattenedKeyPath));
}
}
protected String flattenRelationshipPath(String path, EOEntity entity)
{
if (path.indexOf(Qualifier.KEY_PATH_SEPARATOR_CHAR) >= 0)
{
String relationshipPath = null;
StringTokenizer tokenizer = new StringTokenizer(path, Qualifier.KEY_PATH_SEPARATOR);
while (tokenizer.hasMoreElements())
{
String relationshipName = tokenizer.nextToken();
EORelationship relationship = entity.anyRelationshipNamed(relationshipName);
if (relationship == null)
{
if (!tokenizer.hasMoreElements())
{
return relationshipPath + Qualifier.KEY_PATH_SEPARATOR + relationshipName;
}
else
{
throw new IllegalArgumentException(
"No relationship '"
+ relationshipName
+ "' was found in entity '"
+ entity.name()
+ "' while evaluating relationship path '"
+ path);
}
}
else
{
String element;
if (relationship.isFlattened())
{
element = relationship.relationshipPath();
}
else
{
element = relationship.name();
}
if (relationshipPath != null)
{
relationshipPath =
relationshipPath + Qualifier.KEY_PATH_SEPARATOR + element;
}
else
{
relationshipPath = element;
}
entity = relationship.destinationEntity();
}
}
return relationshipPath;
}
else
{
EORelationship relationship = entity.anyRelationshipNamed(path);
if (relationship == null)
{
return path;
}
else
{
if (relationship.isFlattened())
{
return relationship.relationshipPath();
}
else
{
return relationship.name();
}
}
}
}
protected NSMutableDictionary replaceTableAliasesInExpressionBuffer(
StringBuffer buffer,
EOSQLExpression expression)
{
NSMutableDictionary aliasesByRelationshipPath = expression.aliasesByRelationshipPath();
NSArray subExpressionAliases = aliasesByRelationshipPath.allKeys();
int aliasCount = subExpressionAliases.count();
for (int i = 0; i < aliasCount; i++)
{
String relationshipPath = (String) subExpressionAliases.objectAtIndex(i);
String alias = (String) aliasesByRelationshipPath.objectForKey(relationshipPath);
String newAlias = aliasPrefixForExpression(expression) + i;
RegularExpression regExp = new RegularExpression("[ ,(]" + alias + "[ ,\\,,.]");
int start = 0;
Match match = new Match();
String currentString;
while (regExp
.matches(currentString = buffer.toString(), start, currentString.length(), match))
{
start = match.getBeginning(0) + 1;
buffer.replace(start, match.getEnd(0) - 1, newAlias);
}
aliasesByRelationshipPath.setObjectForKey(newAlias, relationshipPath);
}
return aliasesByRelationshipPath;
}
protected EOSQLExpression expressionForEntity(EOEntity entity)
{
try
{
Class expressionClass =
((EOAdaptor) EOAdaptor.adaptorWithModel(entity.model())).expressionClass();
Constructor constructor =
expressionClass.getConstructor(new Class[] { EOEntity.class });
EOSQLExpression expression =
(EOSQLExpression) constructor.newInstance(new Object[] { entity });
return expression;
}
catch (Exception exception)
{
throw new NSForwardException(exception);
}
}
// Protected class methods
protected static synchronized String aliasPrefixForExpression(EOSQLExpression expression)
{
String prefix = (String) QualifierGenerationSupport.prefixesByExpression.get(expression);
if (prefix == null)
{
prefix = assignPrefixToExpression(expression);
if (prefix == null)
{
System.gc();
prefix = assignPrefixToExpression(expression);
}
if (prefix == null)
{
throw new RuntimeException(
"The number of available alias prefixes was exceeded. "
+ "Fix me if you please");
}
}
return prefix;
}
// Private class methods
private static synchronized String assignPrefixToExpression(EOSQLExpression expression)
{
int count = QualifierGenerationSupport.locks.length;
int availableIndex = 0;
while (availableIndex < count)
{
WeakReference lock = QualifierGenerationSupport.locks[availableIndex];
if ((lock == null) || (lock.get() == null))
{
QualifierGenerationSupport.locks[availableIndex] = null;
break;
}
else
{
availableIndex++;
}
}
if (availableIndex < count)
{
String prefix = QualifierGenerationSupport.prefixes[availableIndex];
QualifierGenerationSupport.locks[availableIndex] = new WeakReference(expression);
QualifierGenerationSupport.prefixesByExpression.put(expression, prefix);
return prefix;
}
else
{
return null;
}
}
}
-----Original Message-----
From: Kaj Hejer [mailto:email@hidden]
Sent: Friday, February 25, 2005 1:33 PM
To: Pierre Bernard
Cc: email@hidden
Subject: Re: [ANN] ExistsInRelationshipQualifier: WHERE EXISTS (SELECT 1
FROM A WHERE ...)
On 17. jan 2005, at 10.22, <email@hidden> wrote:
> Hi!
>
> I have added a new code snipped to my web page.
>
> ExistsInRelationshipQualifier: Qualifier to check for the presence of
> objects
> matching a given qualifier in a to-many relationship. May be combined
> with an
> EONotQualifier to insure the absence of matching objects.
>
> It is available for download on my web page:
> http://homepage.mac.com/i_love_my
>
> P.S.: This code relies on the "Support methods for custom qualifiers"
> code snippet which is also available from my web page.
>
Hi!
Thank you for this and the other codesnippets you have on your webpage!
I have downloaded
<url:http://homepage.mac.com/i_love_my/inSubQueryQualifier.tar.gz> and
<url:http://homepage.mac.com/i_love_my/customQualifiers.tar.gz> but
still QualifierGenerationSupport is complaining it can't find
QualifierUtilities in the following code:
protected EOAttribute attributeForPath(EOEntity entity, String keyPath)
{
return QualifierUtilities.attributeForPath(entity, keyPath);
}
protected EORelationship relationshipForPath(EOEntity entity, String
keyPath)
{
return QualifierUtilities.relationshipForPath(entity, keyPath);
}
Any hints? :)
TIA!
-Kaj :)
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