/**********************************************************************
Copyright (c) 2008 Andy Jefferson and others. All rights reserved.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
Contributors:
...
**********************************************************************/
package org.datanucleus.store.rdbms.sql;
import java.lang.reflect.Modifier;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.Set;
import org.datanucleus.ClassLoaderResolver;
import org.datanucleus.exceptions.NucleusException;
import org.datanucleus.metadata.AbstractClassMetaData;
import org.datanucleus.metadata.DiscriminatorMetaData;
import org.datanucleus.metadata.DiscriminatorStrategy;
import org.datanucleus.store.mapped.DatastoreClass;
import org.datanucleus.store.mapped.DatastoreContainerObject;
import org.datanucleus.store.mapped.DatastoreIdentifier;
import org.datanucleus.store.mapped.mapping.JavaTypeMapping;
import org.datanucleus.store.rdbms.RDBMSStoreManager;
import org.datanucleus.store.rdbms.sql.expression.BooleanExpression;
import org.datanucleus.store.rdbms.sql.expression.NullLiteral;
import org.datanucleus.store.rdbms.sql.expression.SQLExpression;
import org.datanucleus.store.rdbms.sql.expression.SQLExpressionFactory;
import org.datanucleus.store.rdbms.sql.expression.StringLiteral;
import org.datanucleus.util.NucleusLogger;
import org.datanucleus.util.StringUtils;
/**
* Class to generate an SQLStatement for iterating through instances of a particular type (and
* optionally subclasses). Based around the candidate type having subclasses and we use UNIONs to
* return all possible types of candidate. Also allows select of a dummy column to return the
* type for the part of the UNION that the object came from. Please refer to the specific constructors
* for the usages.
* <h3>Supported options</h3>
* <p>
* This generator supports
* <ul>
* <li><b>selectNucleusType</b> : adds a SELECT of a dummy column accessible as "NUCLEUS_TYPE" storing the
* class name.</li>
* <li><b>allowNulls</b> : whether we allow for null objects (only happens when we have a join table
* collection.</li>
* </p>
*/
public class UnionStatementGenerator extends AbstractStatementGenerator
{
/** Name of column added when using "selectNucleusType" */
public static final String NUC_TYPE_COLUMN = "NUCLEUS_TYPE";
/**
* Constructor using the candidateTable as the primary table.
* If we are querying objects of type A with subclasses A1, A2 the query will be of the form :-
* <PRE>
* SELECT ['mydomain.A' AS NUCLEUS_TYPE]
* FROM A THIS
* LEFT OUTER JOIN A1 SUBELEMENT0 ON SUBELEMENT0.A1_ID = THIS.A_ID
* LEFT OUTER JOIN A1 SUBELEMENT1 ON SUBELEMENT0.A2_ID = THIS.A_ID
* WHERE SUBELEMENT0.A1_ID IS NULL
* AND SUBELEMENT0.A2_ID IS NULL
*
* UNION
*
* SELECT ['mydomain.A1' AS NUCLEUS_TYPE]
* FROM A THIS
* INNER JOIN A1 'ELEMENT' ON 'ELEMENT'.A1_ID = THIS.A_ID
*
* UNION
*
* SELECT ['mydomain.A2' AS NUCLEUS_TYPE]
* FROM A THIS
* INNER JOIN A2 'ELEMENT' ON 'ELEMENT'.A2_ID = THIS.A_ID
* </PRE>
* So the first part of the UNION returns the objects just present in the A table, whilst the
* second part returns those just in table A1, and the third part returns those just in table A2.
* @param storeMgr the store manager
* @param clr ClassLoader resolver
* @param candidateType the candidate that we are looking for
* @param includeSubclasses if the subclasses of the candidate should be included in the result
* @param candidateTableAlias Alias to use for the candidate table (optional)
* @param candidateTableGroupName Name of the table group for the candidate(s) (optional)
*/
public UnionStatementGenerator(RDBMSStoreManager storeMgr, ClassLoaderResolver clr,
Class candidateType, boolean includeSubclasses,
DatastoreIdentifier candidateTableAlias, String candidateTableGroupName)
{
super(storeMgr, clr, candidateType, includeSubclasses, candidateTableAlias, candidateTableGroupName);
}
/**
* Constructor using a join table as the primary table.
* If we are querying elements (B) of a collection in class A and B has subclasses B1, B2
* stored via a join table (A_B) the query will be of the form :-
* <PRE>
* SELECT ['mydomain.B' AS NUCLEUS_TYPE]
* FROM A_B T0
* INNER JOIN B T1 ON T0.B_ID_EID = T1.B_ID
* LEFT OUTER JOIN B1 T2 ON T2.B1_ID = T0.B_ID_EID
* LEFT OUTER JOIN B2 T3 ON T3.B2_ID = T0.B_ID_EID
* WHERE T2.B1_ID IS NULL
* AND T3.B2_ID IS NULL
*
* UNION
*
* SELECT ['mydomain.B1' AS NUCLEUS_TYPE]
* FROM A_B THIS
* INNER JOIN B T1 ON T1.B_ID = T0.B_ID_EID
* INNER JOIN B1 T2 ON T2.B1_ID = T1.B_ID
*
* UNION
*
* SELECT ['mydomain.A2' AS NUCLEUS_TYPE]
* FROM A_B THIS
* INNER JOIN B T1 ON T1.B_ID = T0.B_ID_EID
* INNER JOIN B2 T2 ON T2.B2_ID = T1.B_ID
* </PRE>
* So the first part of the UNION returns the objects just present in the B table, whilst the
* second part returns those just in table B1, and the third part returns those just in table B2.
* When we have a join table collection we MUST select the join table since this then caters for the
* situation of having null elements (if we had selected the root element table we wouldn't know if
* there was a null element in the collection).
* @param storeMgr the store manager
* @param clr ClassLoader resolver
* @param candidateType the candidate that we are looking for
* @param includeSubclasses if the subclasses of the candidate should be included in the result
* @param candidateTableAlias Alias to use for the candidate table (optional)
* @param candidateTableGroupName Name of the table group for the candidate(s) (optional)
* @param joinTable Join table linking owner to elements
* @param joinTableAlias any alias to use for the join table in the SQL
* @param joinElementMapping Mapping in the join table to link to the element
*/
public UnionStatementGenerator(RDBMSStoreManager storeMgr, ClassLoaderResolver clr,
Class candidateType, boolean includeSubclasses,
DatastoreIdentifier candidateTableAlias, String candidateTableGroupName,
DatastoreContainerObject joinTable, DatastoreIdentifier joinTableAlias,
JavaTypeMapping joinElementMapping)
{
super(storeMgr, clr, candidateType, includeSubclasses, candidateTableAlias, candidateTableGroupName,
joinTable, joinTableAlias, joinElementMapping);
}
/* (non-Javadoc)
* @see org.datanucleus.store.rdbms.sql.StatementGenerator#setParentStatement(org.datanucleus.store.rdbms.sql.SQLStatement)
*/
public void setParentStatement(SQLStatement stmt)
{
// Never used since we can't have a unioned statement as a subquery, can we ?
this.parentStmt = stmt;
}
private int maxClassNameLength = -1;
/**
* Accessor for the SQL Statement for the candidate [+ subclasses].
* @return The SQL Statement returning objects with a UNION statement.
*/
public SQLStatement getStatement()
{
// Find set of possible candidates (including subclasses of subclasses)
Collection<String> candidateClassNames = new ArrayList<String>();
AbstractClassMetaData acmd =
storeMgr.getMetaDataManager().getMetaDataForClass(candidateType, clr);
candidateClassNames.add(acmd.getFullClassName());
if (includeSubclasses)
{
Set<String> subclasses = storeMgr.getSubClassesForClass(candidateType.getName(), true, clr);
candidateClassNames.addAll(subclasses);
}
// Eliminate any classes that are not instantiable
Iterator<String> iter = candidateClassNames.iterator();
while (iter.hasNext())
{
String className = iter.next();
try
{
Class cls = clr.classForName(className);
if (Modifier.isAbstract(cls.getModifiers()))
{
// Remove since abstract hence not instantiable
iter.remove();
}
}
catch (Exception e)
{
// Remove since class not found
iter.remove();
}
}
if (hasOption(OPTION_SELECT_NUCLEUS_TYPE))
{
// Get the length of the longest class name
iter = candidateClassNames.iterator();
while (iter.hasNext())
{
String className = iter.next();
if (className.length() > maxClassNameLength)
{
maxClassNameLength = className.length();
}
}
}
if (candidateClassNames.isEmpty())
{
// Either passed invalid classes, or no concrete classes with available tables present!
throw new NucleusException("Attempt to generate SQL statement using UNIONs for " +
candidateType.getName() +
" yet there are no concrete classes with their own table available");
}
SQLStatement stmt = null;
iter = candidateClassNames.iterator();
while (iter.hasNext())
{
String candidateClassName = iter.next();
SQLStatement candidateStmt = null;
if (joinTable == null)
{
// Select of candidate table
candidateStmt = getSQLStatementForCandidate(candidateClassName);
}
else
{
// Select of join table and join to element
candidateStmt = getSQLStatementForCandidateViaJoin(candidateClassName);
}
if (candidateStmt != null)
{
if (stmt == null)
{
stmt = candidateStmt;
}
else
{
stmt.union(candidateStmt);
}
}
}
return stmt;
}
/**
* Convenience method to return the SQLStatement for a particular class.
* Returns a SQLStatement with primaryTable of the "candidateTable", and which joins to
* the table of the class (if different).
* @param className The class name to generate the statement for
* @return The SQLStatement
*/
protected SQLStatement getSQLStatementForCandidate(String className)
{
DatastoreClass table = storeMgr.getDatastoreClass(className, clr);
if (table == null)
{
// Subclass-table, so persisted into table(s) of subclasses
NucleusLogger.GENERAL.info("Generation of statement to retrieve objects of type " + candidateType.getName() +
(includeSubclasses ? " including subclasses " : "") + " attempted to include " + className + " but this has no table of its own; ignored");
// TODO Cater for use of single subclass-table
return null;
}
// Start from an SQL SELECT of the candidate table
SQLStatement stmt =
new SQLStatement(storeMgr, candidateTable, candidateTableAlias, candidateTableGroupName);
stmt.setClassLoaderResolver(clr);
stmt.setCandidateClassName(className);
if (table != candidateTable)
{
// INNER JOIN from the root candidate table to this candidates table
JavaTypeMapping candidateIdMapping = candidateTable.getIdMapping();
JavaTypeMapping tableIdMapping = table.getIdMapping();
stmt.innerJoin(null, candidateIdMapping, table, null, tableIdMapping, null,
stmt.getPrimaryTable().getGroupName());
}
// Add any discriminator restriction in this table for the specified class
// Caters for the case where we have more than 1 class stored in this table
SQLExpressionFactory factory = storeMgr.getSQLExpressionFactory();
JavaTypeMapping discriminatorMapping = table.getDiscriminatorMapping(false);
DiscriminatorMetaData discriminatorMetaData = table.getDiscriminatorMetaData();
if (discriminatorMapping != null && discriminatorMetaData.getStrategy() != DiscriminatorStrategy.NONE)
{
// Restrict to valid discriminator values where we have a discriminator specified on this table
String discriminatorValue = className;
if (discriminatorMetaData.getStrategy() == DiscriminatorStrategy.VALUE_MAP)
{
// Get the MetaData for the target class since that holds the "value"
AbstractClassMetaData targetCmd =
storeMgr.getNucleusContext().getMetaDataManager().getMetaDataForClass(className, clr);
discriminatorValue = targetCmd.getInheritanceMetaData().getDiscriminatorMetaData().getValue();
}
SQLExpression discExpr = factory.newExpression(stmt, stmt.getPrimaryTable(), discriminatorMapping);
SQLExpression discVal = factory.newLiteral(stmt, discriminatorMapping, discriminatorValue);
stmt.whereAnd(discExpr.eq(discVal), false);
}
// Eliminate any subclasses (catered for in separate UNION statement)
Iterator<String> subIter = storeMgr.getSubClassesForClass(className, false, clr).iterator();
while (subIter.hasNext())
{
String subclassName = subIter.next();
DatastoreClass[] subclassTables = null;
DatastoreClass subclassTable = storeMgr.getDatastoreClass(subclassName, clr);
if (subclassTable == null)
{
AbstractClassMetaData targetSubCmd =
storeMgr.getNucleusContext().getMetaDataManager().getMetaDataForClass(subclassName, clr);
AbstractClassMetaData[] targetSubCmds = storeMgr.getClassesManagingTableForClass(targetSubCmd, clr);
subclassTables = new DatastoreClass[targetSubCmds.length];
for (int i=0;i<targetSubCmds.length;i++)
{
subclassTables[i] = storeMgr.getDatastoreClass(targetSubCmds[i].getFullClassName(), clr);
}
}
else
{
subclassTables = new DatastoreClass[1];
subclassTables[0] = subclassTable;
}
for (int i=0;i<subclassTables.length;i++)
{
if (subclassTables[i] != table)
{
// Subclass of our class is stored in different table to the candidate so exclude it
// Adds FROM clause of "LEFT OUTER JOIN {subTable} ON ..."
// and WHERE clause of "{subTable}.ID = NULL"
JavaTypeMapping tableIdMapping = table.getIdMapping();
JavaTypeMapping subclassIdMapping = subclassTables[i].getIdMapping();
SQLTable sqlTableSubclass =
stmt.leftOuterJoin(null, tableIdMapping, subclassTables[i], null, subclassIdMapping,
null, stmt.getPrimaryTable().getGroupName());
SQLExpression subclassIdExpr = factory.newExpression(stmt, sqlTableSubclass, subclassIdMapping);
SQLExpression nullExpr = new NullLiteral(stmt, null, null, null);
stmt.whereAnd(subclassIdExpr.eq(nullExpr), false);
}
}
}
if (hasOption(OPTION_SELECT_NUCLEUS_TYPE))
{
// Add SELECT of dummy metadata for this class ("'mydomain.MyClass' AS NUCLEUS_TYPE")
addTypeSelectForClass(stmt, className);
}
return stmt;
}
/**
* Convenience method to return the SQLStatement for a particular class selecting a join table.
* Returns a SQLStatement with primaryTable of the "joinTable", and which joins to
* the table of the class.
* @param className The class name to generate the statement for
* @return The SQLStatement
*/
protected SQLStatement getSQLStatementForCandidateViaJoin(String className)
{
DatastoreClass table = storeMgr.getDatastoreClass(className, clr);
if (table == null)
{
// Only support if there is a single table where the class is actually persisted
// TODO Cater for use of single subclass-table
}
// Start from an SQL SELECT of the join table
SQLStatement stmt = new SQLStatement(storeMgr, joinTable, joinTableAlias, candidateTableGroupName);
stmt.setClassLoaderResolver(clr);
stmt.setCandidateClassName(className);
// INNER/LEFT OUTER JOIN from the join table to the root candidate table
// If we allow nulls we do a left outer join here, otherwise an inner join
JavaTypeMapping candidateIdMapping = candidateTable.getIdMapping();
SQLTable candidateSQLTable = null;
if (hasOption(OPTION_ALLOW_NULLS))
{
// Put element table in same table group since all relates to the elements
candidateSQLTable = stmt.leftOuterJoin(null, joinElementMapping, candidateTable, null,
candidateIdMapping, null, stmt.getPrimaryTable().getGroupName());
}
else
{
// Put element table in same table group since all relates to the elements
candidateSQLTable = stmt.innerJoin(null, joinElementMapping, candidateTable, null,
candidateIdMapping, null, stmt.getPrimaryTable().getGroupName());
}
if (table != candidateTable)
{
// INNER JOIN from the root candidate table to this candidates table
JavaTypeMapping tableIdMapping = table.getIdMapping();
stmt.innerJoin(candidateSQLTable, candidateIdMapping, table, null, tableIdMapping, null,
stmt.getPrimaryTable().getGroupName());
}
// Add any discriminator restriction in the table for the specified class
// Caters for the case where we have more than 1 class stored in this table
SQLExpressionFactory factory = storeMgr.getSQLExpressionFactory();
JavaTypeMapping discriminatorMapping = table.getDiscriminatorMapping(false);
DiscriminatorMetaData discriminatorMetaData = table.getDiscriminatorMetaData();
if (discriminatorMapping != null && discriminatorMetaData.getStrategy() != DiscriminatorStrategy.NONE)
{
// Restrict to valid discriminator value where we have a discriminator specified on this table
BooleanExpression discExpr = SQLStatementHelper.getExpressionForDiscriminatorForClass(stmt,
className, discriminatorMetaData, discriminatorMapping, stmt.getPrimaryTable(), clr);
stmt.whereAnd(discExpr, false);
}
// Eliminate any subclasses (catered for in separate UNION statement)
Iterator<String> subIter = storeMgr.getSubClassesForClass(className, false, clr).iterator();
while (subIter.hasNext())
{
String subclassName = subIter.next();
DatastoreClass[] subclassTables = null;
DatastoreClass subclassTable = storeMgr.getDatastoreClass(subclassName, clr);
if (subclassTable == null)
{
AbstractClassMetaData targetSubCmd =
storeMgr.getNucleusContext().getMetaDataManager().getMetaDataForClass(subclassName, clr);
AbstractClassMetaData[] targetSubCmds = storeMgr.getClassesManagingTableForClass(targetSubCmd, clr);
subclassTables = new DatastoreClass[targetSubCmds.length];
for (int i=0;i<targetSubCmds.length;i++)
{
subclassTables[i] = storeMgr.getDatastoreClass(targetSubCmds[i].getFullClassName(), clr);
}
}
else
{
subclassTables = new DatastoreClass[1];
subclassTables[0] = subclassTable;
}
for (int i=0;i<subclassTables.length;i++)
{
if (subclassTables[i] != table)
{
// Subclass of our class is stored in different table to the candidate so exclude it
// Adds FROM clause of "LEFT OUTER JOIN {subTable} ON ..."
// and WHERE clause of "{subTable}.ID = NULL"
JavaTypeMapping subclassIdMapping = subclassTables[i].getIdMapping();
SQLTable sqlTableSubclass =
stmt.leftOuterJoin(null, joinElementMapping, subclassTables[i], null,
subclassIdMapping, null, stmt.getPrimaryTable().getGroupName());
SQLExpression subclassIdExpr = factory.newExpression(stmt, sqlTableSubclass, subclassIdMapping);
SQLExpression nullExpr = new NullLiteral(stmt, null, null, null);
stmt.whereAnd(subclassIdExpr.eq(nullExpr), false);
}
}
}
if (hasOption(OPTION_SELECT_NUCLEUS_TYPE))
{
// Add SELECT of dummy metadata for this class ("'mydomain.MyClass' AS NUCLEUS_TYPE")
addTypeSelectForClass(stmt, className);
}
return stmt;
}
/**
* Convenience method to add a SELECT of a dummy column accessible as "NUCLEUS_TYPE" storing the
* class name.
* @param stmt SQLStatement
* @param className Name of the class
*/
private void addTypeSelectForClass(SQLStatement stmt, String className)
{
if (hasOption(OPTION_SELECT_NUCLEUS_TYPE))
{
// Add SELECT of dummy metadata for this class ("'mydomain.MyClass' AS NUCLEUS_TYPE")
/*if (hasOption(OPTION_ALLOW_NULLS))
{
NullLiteral nullLtl = new NullLiteral(stmt, null, null, null);
stmt.select(nullLtl, NUC_TYPE_COLUMN);
}
else
{*/
// Add SELECT of dummy column accessible as "NUCLEUS_TYPE" containing the classname
JavaTypeMapping m = storeMgr.getMappingManager().getMapping(String.class);
String nuctypeName = className;
if (maxClassNameLength > nuctypeName.length())
{
nuctypeName = StringUtils.leftAlignedPaddedString(nuctypeName, maxClassNameLength);
}
StringLiteral lit = new StringLiteral(stmt, m, nuctypeName, null);
stmt.select(lit, NUC_TYPE_COLUMN);
/*}*/
}
}
}