DynamicJoin.java
/*
** Module : DynamicJoin.java
** Abstract : Natural join helper implementation for dynamic queries
**
** Copyright (c) 2006-2023, Golden Code Development Corporation.
**
** -#- -I- --Date-- --JPRM-- -----------------------------------Description-----------------------------------
** 001 ECF 20060309 @25002 Created initial version. Natural join helper
** implementation used by dynamic query types.
** 002 ECF 20060621 @27516 Fix to setup method. Use lowercased short
** name of DMO interface when composing name of
** foreign record property.
** 003 ECF 20060803 @28389 Minor change to getParameterType() method.
** Renamed parameter and changed javadoc.
** 004 ECF 20070629 @35297 Minor optimization. Replaced StringBuffer
** with StringBuilder.
** 005 SVL 20080421 @38075 Updated to meet the AbstractJoin function
** signatures which may return multiple query
** substitution parameters.
** 006 CA 20080515 @38283 Fixed regression introduced by H005: the
** parameter type must always be retrieved
** from the foreign class.
** 007 ECF 20080822 @39560 Added isServerJoin(). Reports whether join
** occurs at database server or within P2J
** runtime environment.
** 008 GES 20090424 @41938 Import change.
** 009 ECF 20090428 @42973 Fixed setup(). Use record buffer's snapshot to
** resolve parameter in non-dereference case.
** 010 SVL 20120331 Upgraded to Hibernate 4.
** 011 SVL 20140210 Use HQLExpression instead of HQL string.
** 012 EVL 20160223 Javadoc fixes to make compatible with Oracle Java 8 for Solaris 10.
** 013 ECF 20200906 New ORM implementation.
** OM 20221103 New class names for FQLPreprocessor, FQLExpression, FQLBundle, and FQLCache.
** 014 OM 20230404 The join navigation key may contain null/unknown values.
*/
/*
** This program is free software: you can redistribute it and/or modify
** it under the terms of the GNU Affero General Public License as
** published by the Free Software Foundation, either version 3 of the
** License, or (at your option) any later version.
**
** This program 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
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**
** You may find a copy of the GNU Affero GPL version 3 at the following
** location: https://www.gnu.org/licenses/agpl-3.0.en.html
**
** Additional terms under GNU Affero GPL version 3 section 7:
**
** Under Section 7 of the GNU Affero GPL version 3, the following additional
** terms apply to the works covered under the License. These additional terms
** are non-permissive additional terms allowed under Section 7 of the GNU
** Affero GPL version 3 and may not be removed by you.
**
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**
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*/
package com.goldencode.p2j.persist;
import java.util.List;
import java.util.Collections;
import java.io.Serializable;
import com.goldencode.p2j.persist.orm.*;
import com.goldencode.util.*;
/**
* An implementation of a natural join helper used by dynamic query types.
* The FQL query string snippet created by this class joins the local DMO
* with the inverse DMO using a query substitution parameter (<code>?</code>)
* to represent the shared record. For instance, given the three table
* relationship:
* <pre>
* Person [one-to-many] ---> PersonAddress [many-to-one] ---> Address
* </pre>
* and the following multi-table join in Progress
* <pre>
* for each person,
* each person-address of person,
* each address of person-address:
* ...
* </pre>
* the first join (<code>person-address of person</code>) is represented as
* follows:
* <pre>
* personAddress.personRecord = ?
* </pre>
* where <code>PersonAddress</code> is the local DMO and Person the foreign
* DMO; and the second join (<code>address of person-address</code>) is
* represented as follows:
* <pre>
* address = ?
* </pre>
* where <code>Address</code> is the local DMO and PersonAddress the foreign
* DMO.
*/
final class DynamicJoin
extends AbstractJoin
{
/** An object which resolves the substitution parameter */
private ParameterResolver resolver;
/**
* Constructor.
*
* @param local
* Local record buffer (the refering end of the join).
* @param inverse
* Inverse record buffer (the referent end of the join).
*/
DynamicJoin(RecordBuffer local, final RecordBuffer inverse)
{
super(local, inverse);
}
/**
* Report whether the join represented by this object takes place at the
* database server, or within runtime code.
*
* @return <code>true</code> if the join happens at the server;
* <code>false</code> if it happens in the runtime.
*/
protected boolean isServerJoin()
{
return false;
}
/**
* Generate the FQL where clause snippets which will be inserted into the overall FQL statement executed
* by the enclosing query. See the class description for additional details on the composition of the
* clause.
*
* @param local
* Local record buffer (the referring end of the join).
* @param inverse
* Inverse record buffer (the referent end of the join).
* @param info
* Relation descriptor object.
* @param dereference
* {@code true} if the local DMO contains a reference to the foreign record, which must be
* dereferenced in the FQL query; {@code false} if the local DMO <i>is</i> the foreign record,
* referenced by the inverse DMO.
*
* @return FQL where clause snippets used to perform the join. A bi-dimensional array of clauses are used.
* The first dimension is the size of the join (aka the number of fields paired) and the second is
* always two: the first (NULL_FIELD) is used when the joined field is {@code null} and the second
* (NOT_NULL_FIELD) is used when the join field is not unknown.
*/
protected FQLExpression[][] generateFQL(RecordBuffer local,
RecordBuffer inverse,
RelationInfo info,
boolean dereference)
{
FQLExpression[][] ret = new FQLExpression[1][2];
ret[0][NULL_FIELD] = new FQLExpression(local.getDMOAlias());
ret[0][NOT_NULL_FIELD] = new FQLExpression(local.getDMOAlias());
if (dereference)
{
ret[0][NULL_FIELD].append(".").append(info.getForeignAlias()).append("Record");
ret[0][NOT_NULL_FIELD].append(".").append(info.getForeignAlias()).append("Record");
}
ret[0][NULL_FIELD].append(" is null");
ret[0][NOT_NULL_FIELD].append(" = ", true);
return ret;
}
/**
* Determine the type of the query substitution parameter. This will be a Hibernate entity type
* which wrappers the implementation class of the buffer.
*
* @param info
* Relation descriptor object.
* @param dereference
* {@code true} if the local DMO contains a reference to the foreign record, which
* must be dereferenced in the FQL query; {@code false} if the local DMO <i>is</i> the
* foreign record, referenced by the inverse DMO.
*
* @return A singleton list with the appropriate Hibernate type for the query substitution
* parameter is used for this join.
*/
@Override
protected List<FqlType> getParameterTypes(RelationInfo info, boolean dereference)
{
// TODO: implement w/o Hibernate
/*
// always return the foreign class, because the RelationInfo object is
// already dereferenced by the AbstractJoin c'tor
TypeHelper th = inverse.buffer().getPersistence().getSession().getTypeHelper();
return Collections.singletonList(th.entity(info.getForeignClass()));
*/
return null;
}
/**
* Perform additional setup necessary to create the object which will
* resolve the query substitution parameter at query execution time.
*
* @param local
* Local record buffer (the refering end of the join).
* @param inverse
* Inverse record buffer (the referent end of the join).
* @param info
* Relation descriptor object.
* @param dereference
* <code>true</code> if the local DMO contains a reference to the
* foreign record, which must be dereferenced in the FQL query;
* <code>false</code> if the local DMO <i>is</i> the foreign
* record, referenced by the inverse DMO.
*/
protected void setup(RecordBuffer local,
final RecordBuffer inverse,
RelationInfo info,
boolean dereference)
{
// Initialize query substitution parameter resolver.
if (dereference)
{
this.resolver = () -> Collections.singletonList((Serializable) inverse.getCurrentRecord());
}
else
{
String prop = StringHelper.changeCase(local.getDMOName(), false) + "Record";
this.resolver = new ParameterResolver()
{
private FieldReference ref = new FieldReference(inverse, prop);
public List<Serializable> resolve()
{
return Collections.singletonList(
(Serializable) ref.get(inverse.getSnapshot()));
}
};
}
}
/**
* Get the DMO instance which will be used as the query substitution
* parameter. Utilizes the inner helper class {@link
* DynamicJoin.ParameterResolver} to do its work.
*
* @return Query substitution parameter; a singleton list with DMO
* instance.
*/
List<Serializable> getParameters()
{
return resolver.resolve();
}
/**
* An internal API used by this class to abstract the resolution of the
* query substitution parameter at query execution time.
*/
private interface ParameterResolver
{
/**
* Get the DMO instance which will be used as the query substitution
* parameter.
*
* @return Query substitution parameter; a singleton list with DMO
* instance.
*/
public List<Serializable> resolve();
}
}