com.tomtom.speedtools.mongodb.mappers.CollectionMapper Maven / Gradle / Ivy

Show more of this group Show more artifacts with this name
Show all versions of mongodb Show documentation
Generic utility classes for project SpeedTools.
There is a newer version: 3.4.4
/*
 * Copyright (C) 2012-2017. TomTom International BV (http://tomtom.com).
 *
 * 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.tomtom.speedtools.mongodb.mappers;

import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.List;

public class CollectionMapper extends Mapper> {

    @Nullable
    private Class> elementMapperType;
    @Nullable
    private Mapper elementMapper;

    @Nonnull
    public static  CollectionMapper create(@Nonnull final Class> elementMapperType) {
        assert elementMapperType != null;
        return new CollectionMapper<>(elementMapperType, null);
    }

    @Nonnull
    public static  CollectionMapper create(@Nonnull final Mapper elementMapper) {
        assert elementMapper != null;
        return new CollectionMapper<>(null, elementMapper);
    }

    protected CollectionMapper(@Nullable final Class> elementMapperType,
                               @Nullable final Mapper elementMapper) {
        super();
        this.elementMapperType = elementMapperType;
        this.elementMapper = elementMapper;
    }

    @Nonnull
    public Mapper getElementMapper() {
        assert elementMapper != null;
        return elementMapper;
    }

    @Override
    public Collection fromDb(@Nullable final Object dbValue) throws MapperException {

        // Only one object? Map it to a singleton-set.
        final Collection collection;
        if (dbValue == null) {
            collection = Collections.emptyList();
        } else if (dbValue instanceof Collection) {
            collection = (Collection) dbValue;
        } else {
            collection = Collections.singletonList(dbValue);
        }

        // Gather mapped nested entities.
        final List values = new ArrayList<>();

        // Loop over the collection.
        assert elementMapper != null;
        for (final Object elt : collection) {

            final T value = elementMapper.fromDb(elt);
            if (value != null) {
                values.add(value);
            }
        }
        return values;
    }

    @Nullable
    @Override
    public List