All Downloads are FREE. Search and download functionalities are using the official Maven repository.
  • Log In
  • Register

    • com.mysema.query.mongodb.MongodbQuery Maven / Gradle / Ivy

    The newest version!
    /*
 * Copyright 2015, The Querydsl Team (http://www.querydsl.com/team)
 *
 * 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();
    }

}    
    
    
    

    




    
    
    © 2015 - 2025 Weber Informatics LLC | Privacy Policy