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com.mysema.query.mongodb.MongodbQuery Maven / Gradle / Ivy
/*
* Copyright 2011, Mysema Ltd
*
* 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.
*/
package com.mysema.query.mongodb;
import javax.annotation.Nullable;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import com.google.common.base.Function;
import com.google.common.collect.HashMultimap;
import com.google.common.collect.Multimap;
import com.mongodb.*;
import com.mysema.commons.lang.CloseableIterator;
import com.mysema.query.*;
import com.mysema.query.support.QueryMixin;
import com.mysema.query.types.*;
import com.mysema.query.types.path.CollectionPathBase;
/**
* MongodbQuery provides a general Querydsl query implementation with a pluggable DBObject to Bean transformation
*
* @author laimw
*
* @param
*/
public abstract class MongodbQuery implements SimpleQuery>, SimpleProjectable {
@SuppressWarnings("serial")
private static class NoResults extends RuntimeException {}
private final MongodbSerializer serializer;
private final QueryMixin> queryMixin;
private final DBCollection collection;
private final Function transformer;
private ReadPreference readPreference;
/**
* Create a new MongodbQuery instance
*
* @param collection
* @param transformer
* @param serializer
*/
public MongodbQuery(DBCollection collection, Function transformer, MongodbSerializer serializer) {
this.queryMixin = new QueryMixin>(this, new DefaultQueryMetadata().noValidate(), false);
this.transformer = transformer;
this.collection = collection;
this.serializer = serializer;
}
/**
* Define a join
*
* @param ref
* @param target
* @return
*/
public JoinBuilder join(Path ref, Path target) {
return new JoinBuilder(queryMixin, ref, target);
}
/**
* Define a join
*
* @param ref
* @param target
* @return
*/
public JoinBuilder join(CollectionPathBase ref, Path target) {
return new JoinBuilder(queryMixin, ref, target);
}
/**
* Define a constraint for an embedded object
*
* @param collection
* @param target
* @return
*/
public AnyEmbeddedBuilder anyEmbedded(Path> collection, Path target) {
return new AnyEmbeddedBuilder(queryMixin, collection);
}
protected abstract DBCollection getCollection(Class type);
@Override
public boolean exists() {
try {
QueryMetadata metadata = queryMixin.getMetadata();
Predicate filter = createFilter(metadata);
return collection.findOne(createQuery(filter)) != null;
} catch (NoResults ex) {
return false;
}
}
@Nullable
protected Predicate createFilter(QueryMetadata metadata) {
Predicate filter;
if (!metadata.getJoins().isEmpty()) {
filter = ExpressionUtils.allOf(metadata.getWhere(), createJoinFilter(metadata));
} else {
filter = metadata.getWhere();
}
return filter;
}
@Nullable
protected Predicate createJoinFilter(QueryMetadata metadata) {
Multimap, Predicate> predicates = HashMultimap., Predicate>create();
List joins = metadata.getJoins();
for (int i = joins.size() - 1; i >= 0; i--) {
JoinExpression join = joins.get(i);
Path source = (Path)((Operation)join.getTarget()).getArg(0);
Path target = (Path)((Operation)join.getTarget()).getArg(1);
Collection extraFilters = predicates.get(target.getRoot());
Predicate filter = ExpressionUtils.allOf(join.getCondition(), allOf(extraFilters));
List ids = getIds(target.getType(), filter);
if (ids.isEmpty()) {
throw new NoResults();
}
Path path = new PathImpl(String.class, source, "$id");
predicates.put(source.getRoot(), ExpressionUtils.in(path, ids));
}
Path source = (Path)((Operation)joins.get(0).getTarget()).getArg(0);
return allOf(predicates.get(source.getRoot()));
}
private Predicate allOf(Collection predicates) {
return predicates != null ? ExpressionUtils.allOf(predicates) : null;
}
protected List getIds(Class targetType, Predicate condition) {
DBCollection collection = getCollection(targetType);
// TODO : fetch only ids
DBCursor cursor = createCursor(collection, condition, Collections.>emptyList(),
QueryModifiers.EMPTY, Collections.>emptyList());
if (cursor.hasNext()) {
List ids = new ArrayList(cursor.count());
for (DBObject obj : cursor) {
ids.add(obj.get("_id"));
}
return ids;
} else {
return Collections.emptyList();
}
}
@Override
public boolean notExists() {
return !exists();
}
@Override
public MongodbQuery distinct() {
return queryMixin.distinct();
}
public MongodbQuery where(Predicate e) {
return queryMixin.where(e);
}
@Override
public MongodbQuery where(Predicate... e) {
return queryMixin.where(e);
}
@Override
public MongodbQuery limit(long limit) {
return queryMixin.limit(limit);
}
@Override
public MongodbQuery offset(long offset) {
return queryMixin.offset(offset);
}
@Override
public MongodbQuery restrict(QueryModifiers modifiers) {
return queryMixin.restrict(modifiers);
}
public MongodbQuery orderBy(OrderSpecifier o) {
return queryMixin.orderBy(o);
}
@Override
public MongodbQuery orderBy(OrderSpecifier... o) {
return queryMixin.orderBy(o);
}
@Override
public MongodbQuery set(ParamExpression param, T value) {
return queryMixin.set(param, value);
}
public CloseableIterator iterate(Path... paths) {
queryMixin.addProjection(paths);
return iterate();
}
@Override
public CloseableIterator iterate() {
final DBCursor cursor = createCursor();
return new CloseableIterator() {
@Override
public boolean hasNext() {
return cursor.hasNext();
}
@Override
public K next() {
return transformer.apply(cursor.next());
}
@Override
public void remove() {
}
@Override
public void close() {
}
};
}
public List list(Path... paths) {
queryMixin.addProjection(paths);
return list();
}
@Override
public List list() {
try {
DBCursor cursor = createCursor();
List results = new ArrayList();
for (DBObject dbObject : cursor) {
results.add(transformer.apply(dbObject));
}
return results;
} catch (NoResults ex) {
return Collections.emptyList();
}
}
protected DBCursor createCursor() {
QueryMetadata metadata = queryMixin.getMetadata();
Predicate filter = createFilter(metadata);
return createCursor(collection, filter, metadata.getProjection(), metadata.getModifiers(), metadata.getOrderBy());
}
protected DBCursor createCursor(DBCollection collection, @Nullable Predicate where, List> projection,
QueryModifiers modifiers, List> orderBy) {
DBCursor cursor = collection.find(createQuery(where), createProjection(projection));
Integer limit = modifiers.getLimitAsInteger();
Integer offset = modifiers.getOffsetAsInteger();
if (limit != null) {
cursor.limit(limit.intValue());
}
if (offset != null) {
cursor.skip(offset.intValue());
}
if (orderBy.size() > 0) {
cursor.sort(serializer.toSort(orderBy));
}
if (readPreference != null) {
cursor.setReadPreference(readPreference);
}
return cursor;
}
private DBObject createProjection(List> projection) {
if (!projection.isEmpty()) {
DBObject obj = new BasicDBObject();
for (Expression expr : projection) {
obj.put((String)serializer.handle(expr), 1);
}
return obj;
}
return null;
}
public K singleResult(Path...paths) {
queryMixin.addProjection(paths);
return singleResult();
}
@Override
public K singleResult() {
try {
DBCursor c = createCursor().limit(1);
if (c.hasNext()) {
return transformer.apply(c.next());
} else {
return null;
}
} catch (NoResults ex) {
return null;
}
}
public K uniqueResult(Path... paths) {
queryMixin.addProjection(paths);
return uniqueResult();
}
@Override
public K uniqueResult() {
try {
Long limit = queryMixin.getMetadata().getModifiers().getLimit();
if (limit == null) {
limit = 2l;
}
DBCursor c = createCursor().limit(limit.intValue());
if (c.hasNext()) {
K rv = transformer.apply(c.next());
if (c.hasNext()) {
throw new NonUniqueResultException();
}
return rv;
} else {
return null;
}
} catch (NoResults ex) {
return null;
}
}
public SearchResults listResults(Path... paths) {
queryMixin.addProjection(paths);
return listResults();
}
@Override
public SearchResults listResults() {
try {
long total = count();
if (total > 0l) {
return new SearchResults(list(), queryMixin.getMetadata().getModifiers(), total);
} else {
return SearchResults.emptyResults();
}
} catch (NoResults ex) {
return SearchResults.emptyResults();
}
}
@Override
public long count() {
try {
Predicate filter = createFilter(queryMixin.getMetadata());
return collection.count(createQuery(filter));
} catch (NoResults ex) {
return 0l;
}
}
private DBObject createQuery(@Nullable Predicate predicate) {
if (predicate != null) {
return (DBObject) serializer.handle(predicate);
} else {
return new BasicDBObject();
}
}
public void setReadPreference(ReadPreference readPreference) {
this.readPreference = readPreference;
}
@Override
public String toString() {
return createQuery(queryMixin.getMetadata().getWhere()).toString();
}
}
