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Subqueries in FROM clause #50

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Subqueries in FROM clause with internal paging with HibernateQueryPro…
Mar 18, 2021
8bf76b0
Subqueries in FROM clause with internal paging with HibernateQueryPro…
Mar 18, 2021
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128 changes: 118 additions & 10 deletions nativeCriteria-core/src/main/java/com/github/pnowy/nc/core/NativeCriteria.java
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Original file line number Diff line number Diff line change
Expand Up @@ -3,11 +3,18 @@
import com.github.pnowy.nc.core.expressions.NativeExp;
import com.github.pnowy.nc.core.expressions.NativeJoin;
import com.github.pnowy.nc.core.expressions.NativeProjection;
import com.github.pnowy.nc.core.hibernate.HibernateQueryProvider;
import com.github.pnowy.nc.core.mappers.CriteriaResultTransformer;
import com.github.pnowy.nc.core.mappers.NativeObjectMapper;
import com.github.pnowy.nc.utils.Strings;
import com.google.common.base.Stopwatch;
import com.google.common.collect.Lists;
import org.hibernate.Session;
import org.hibernate.dialect.pagination.AbstractLimitHandler;
import org.hibernate.dialect.pagination.LimitHandler;
import org.hibernate.engine.jdbc.spi.JdbcServices;
import org.hibernate.engine.spi.RowSelection;
import org.hibernate.engine.spi.SessionImplementor;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

Expand All @@ -29,7 +36,7 @@ public class NativeCriteria implements NativeExp {
/**
* Hibernate session.
*/
private NativeQueryProvider nativeProvider;
private final NativeQueryProvider nativeProvider;
/**
* Native query.
*/
Expand All @@ -40,6 +47,11 @@ public class NativeCriteria implements NativeExp {
*/
private Map<String, String> tables;

/**
* Subqueries with aliases to FROM clause.
*/
private Map<NativeCriteria, String> subQueries;

/**
* Joins.
*/
Expand Down Expand Up @@ -97,7 +109,7 @@ private enum Operator {
/**
* The value.
*/
private String value;
private final String value;

/**
* Instantiates a new operator.
Expand Down Expand Up @@ -136,13 +148,38 @@ public NativeCriteria(NativeQueryProvider nativeProvider, String mainTable, Stri
throw new IllegalStateException("mainAlias is null");
}

initCollections();

this.nativeProvider = nativeProvider;
this.distinct = false;

// main table
this.tables = new LinkedHashMap<>();
this.tables.put(mainTable, mainAlias);
}

public NativeCriteria(NativeQueryProvider nativeProvider, NativeCriteria subQuery, String mainAlias) {
if (nativeProvider == null) {
throw new IllegalStateException("NativeProvider is null!");
}
if (subQuery == null) {
throw new IllegalStateException("subQuery is null");
}
if (Strings.isBlank(mainAlias)) {
throw new IllegalStateException("mainAlias is null");
}

initCollections();

this.nativeProvider = nativeProvider;
this.distinct = false;

// main subQuery
this.subQueries.put(subQuery, mainAlias);
}

private void initCollections() {
this.tables = new LinkedHashMap<>();
this.subQueries = new LinkedHashMap<>();
this.whereExps = new LinkedHashMap<>();
this.havingExps = new LinkedHashMap<>();
this.joins = new ArrayList<>();
Expand All @@ -160,6 +197,18 @@ public NativeCriteria addTable(String tableName, String tableAlias) {
return this;
}

/**
* Add sub query to FROM clause.
*
* @param query sub query
* @param alias alias for sub query
* @return the native criteria
*/
public NativeCriteria addSubquery(NativeCriteria query, String alias) {
this.subQueries.put(query, alias);
return this;
}

/**
* Set projection.
*
Expand Down Expand Up @@ -470,9 +519,9 @@ private void appendHavingSQL(StringBuilder sqlBuilder) {
first = false;
} else {
sqlBuilder.append(exp.getValue().getValue())
.append(SPACE)
.append(exp.getKey().toSQL())
.append(SPACE);
.append(SPACE)
.append(exp.getKey().toSQL())
.append(SPACE);
}
}
}
Expand Down Expand Up @@ -556,6 +605,17 @@ private void appendFromSQL(StringBuilder sqlBuilder) {
}
}

first = true;
for (Entry<NativeCriteria, String> from : subQueries.entrySet()) {
String sql = from.getKey().toSQL();
if (first) {
sqlBuilder.append("(").append(sql).append(")").append(SPACE).append(from.getValue());
first = false;
} else {
sqlBuilder.append(", ").append("(").append(sql).append(")").append(SPACE).append(from.getValue());
}
}

sqlBuilder.append(SPACE);
}

Expand Down Expand Up @@ -630,6 +690,23 @@ public String toSQL() {
appendOrderBySQL(sqlBuilder);

String sql = sqlBuilder.toString();

if (getLimitHandler() != null && limit != null && offset != null) {
final AbstractLimitHandler limitHandler = getLimitHandler();

RowSelection rowSelection = new RowSelection();
rowSelection.setFirstRow(offset);
rowSelection.setMaxRows(limit);

sql = limitHandler.processSql(sqlBuilder.toString(), rowSelection)
.replaceFirst("[?]", limitHandler.bindLimitParametersInReverseOrder()
? String.valueOf(limitHandler.useMaxForLimit() ? limit + offset : limit)
: String.valueOf(offset))
.replaceFirst("[?]", limitHandler.bindLimitParametersInReverseOrder()
? String.valueOf(offset)
: String.valueOf(limitHandler.useMaxForLimit() ? limit + offset : limit));
}

LOG.debug("NcSQL: {}", sql);
return sql;
}
Expand All @@ -643,6 +720,9 @@ public void setValues(NativeQuery sqlQuery) {
}
}

for (NativeExp exp : subQueries.keySet()) {
exp.setValues(sqlQuery);
}
// parameters where clause
for (NativeExp exp : whereExps.keySet()) {
exp.setValues(sqlQuery);
Expand All @@ -653,11 +733,39 @@ public void setValues(NativeQuery sqlQuery) {
for (NativeExp join : joins) {
join.setValues(sqlQuery);
}
if (limit != null) {
sqlQuery.setMaxResults(limit);

if (getLimitHandler() == null) {
if (limit != null) {
sqlQuery.setMaxResults(limit);
}
if (offset != null) {
sqlQuery.setFirstResult(offset);
}
}
if (offset != null) {
sqlQuery.setFirstResult(offset);
}

private AbstractLimitHandler getLimitHandler() {
if (!(nativeProvider instanceof HibernateQueryProvider)) {
return null;
}

Session session = ((HibernateQueryProvider) nativeProvider).getSession();
if (!(session instanceof SessionImplementor)) {
return null;
}

JdbcServices jdbcServices = ((SessionImplementor) session).getSessionFactory().getJdbcServices();
if (jdbcServices == null
|| jdbcServices.getDialect() == null
|| jdbcServices.getDialect().getLimitHandler() == null) {
return null;
}

LimitHandler limitHandler = jdbcServices.getDialect().getLimitHandler();
if (!(limitHandler instanceof AbstractLimitHandler)) {
return null;
}

return (AbstractLimitHandler) limitHandler;
}
}
7 changes: 6 additions & 1 deletion ...riteria-core/src/main/java/com/github/pnowy/nc/core/hibernate/HibernateQueryProvider.java
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Original file line number Diff line number Diff line change
Expand Up @@ -10,7 +10,8 @@
* Default hibernate provider.
*/
public class HibernateQueryProvider implements NativeQueryProvider {
private Session session;

private final Session session;

public HibernateQueryProvider(Session session) {
this.session = session;
Expand All @@ -24,4 +25,8 @@ public HibernateQueryProvider(EntityManager entityManager) {
public NativeQuery getNativeQuery(String sql) {
return new HibernateNativeQuery(sql, session.createSQLQuery(sql));
}

public Session getSession() {
return session;
}
}