Examples with Expression com.mysema.query.types.Expression used on opensource projects

Example 1 with Expression

use of com.mysema.query.types.Expression in project opencast by opencast.

the class AbstractASelectQuery method run.

private AResult run(JPAQueryFactory f) {
    // run query and map the result to records
    final long startTime = System.nanoTime();
    // resolve AST
    final SelectQueryContribution r = contributeSelect(f);
    final boolean toFetchProperties = r.fetch.exists(Booleans.<Expression<?>>eq(QPropertyDto.propertyDto));
    // # create Querydsl query
    final JPAQuery q = f.query();
    // # from
    {
        // Make sure that the snapshotDto is always contained in the from clause because the media package ID and
        // the ID are always selected.
        // Use a mutable hash set to be able to use the removeAll operation.
        final Set<EntityPath<?>> from = Stream.<EntityPath<?>>mk(Q_SNAPSHOT).append(// all collected from clauses
        r.from).append(// all from clauses from the joins
        r.join.map(Join.getFrom)).toSet(SetB.MH);
        // Now remove everything that will be joined. Adding them in both the from and a join
        // clause is not allowed.
        from.removeAll(r.join.map(Join.getJoin).toSet());
        q.from(JpaFns.toEntityPathArray(from));
    }
    // # join
    if (!r.join.isEmpty()) {
        // Group joins by entity and combine all "on" clauses with "or" expressions.
        // This way there is only one join clause per distinct entity which eliminates the need to alias entities
        // like this `new QPropertyDto("alias")`.
        // Entity aliasing produces many issues which seem to cause a huge rewrite of the query building mechanism
        // so it should be prevented at all costs.
        final Map<EntityPath<?>, BooleanExpression> joins = r.join.foldl(new HashMap<EntityPath<?>, BooleanExpression>(), new Fn2<Map<EntityPath<?>, BooleanExpression>, Join, Map<EntityPath<?>, BooleanExpression>>() {

            @Override
            public Map<EntityPath<?>, BooleanExpression> apply(Map<EntityPath<?>, BooleanExpression> sum, Join join) {
                // get the on expression saved with the join, may be null
                final BooleanExpression existing = sum.get(join.join);
                final BooleanExpression combined;
                // combine the existing and the current expression
                if (existing == null) {
                    combined = join.on;
                } else if (existing.equals(join.on)) {
                    // if both expressions are equal there is no need to combine them
                    combined = existing;
                } else {
                    // if different combine with logical "or"
                    combined = existing.or(join.on);
                }
                sum.put(join.join, combined);
                return sum;
            }
        });
        for (final Map.Entry<EntityPath<?>, BooleanExpression> j : joins.entrySet()) {
            q.leftJoin(j.getKey()).on(j.getValue());
        }
    }
    // # where
    q.where(r.where.orNull());
    // # paging
    for (Integer a : r.offset) {
        q.offset(a);
    }
    for (Integer a : r.limit) {
        q.limit(a);
    }
    // # order
    for (OrderSpecifier<?> a : r.order) {
        q.orderBy(a);
    }
    // # distinct
    if (!toFetchProperties) {
        // if no properties shall be fetched the result set can be distinct
        q.distinct();
    }
    // # fetch
    // create parameters for fetch clause, i.e. Querydsl's list() method
    final List<Expression<?>> fetch;
    {
        // check if the media package ID needs to be selected separately
        if (r.fetch.exists(MandatoryFetch.exists)) {
            fetch = r.fetch.toList();
        } else {
            fetch = r.fetch.append(MandatoryFetch.fetch).toList();
        }
    }
    // Run the query and transform the result into records
    final Stream<ARecordImpl> records;
    {
        // run query
        am.getDb().logQuery(q);
        final List<Tuple> result = q.list(JpaFns.toExpressionArray(fetch));
        logger.debug("Pure query ms " + (System.nanoTime() - startTime) / 1000000);
        // map result based on the fact whether properties have been fetched or not
        if (!toFetchProperties) {
            // No properties have been fetched -> each result row (tuple) is a distinct record (snapshot).
            records = $($(result).map(toARecord(r))).map(new Fn<ARecordImpl, ARecordImpl>() {

                @Override
                public ARecordImpl apply(ARecordImpl record) {
                    Opt<Snapshot> snapshotOpt = record.getSnapshot();
                    Snapshot snapshot = null;
                    if (snapshotOpt.isSome()) {
                        // make sure the delivered media package has valid URIs
                        snapshot = am.getHttpAssetProvider().prepareForDelivery(snapshotOpt.get());
                    }
                    return new ARecordImpl(record.getSnapshotId(), record.getMediaPackageId(), record.getProperties(), snapshot);
                }
            });
        } else {
            logger.trace("Fetched properties");
            // Properties have been fetched -> there may be multiple rows (tuples) per snapshot because of the join with the property table.
            // Extract records and properties and link them together.
            // group properties after their media package ID and make sure that no duplicate properties occur
            final Map<String, Set<Property>> propertiesPerMp = $(result).bind(toProperty).foldl(new HashMap<String, Set<Property>>(), new Fn2<Map<String, Set<Property>>, Property, Map<String, Set<Property>>>() {

                @Override
                public Map<String, Set<Property>> apply(Map<String, Set<Property>> sum, Property p) {
                    final String mpId = p.getId().getMediaPackageId();
                    final Set<Property> props = sum.get(mpId);
                    if (props != null) {
                        props.add(p);
                    } else {
                        sum.put(mpId, SetB.MH.mk(p));
                    }
                    return sum;
                }
            });
            // group records after their media package ID
            final Map<String, List<ARecordImpl>> distinctRecords = $($(result).map(toARecord(r)).toSet()).groupMulti(ARecordImpl.getMediaPackageId);
            records = $(distinctRecords.values()).bind(new Fn<List<ARecordImpl>, Iterable<ARecordImpl>>() {

                @Override
                public Iterable<ARecordImpl> apply(List<ARecordImpl> records) {
                    return $(records).map(new Fn<ARecordImpl, ARecordImpl>() {

                        @Override
                        public ARecordImpl apply(ARecordImpl record) {
                            final Set<Property> properties = propertiesPerMp.get(record.getMediaPackageId());
                            final Stream<Property> p = properties != null ? $(properties) : Stream.<Property>empty();
                            Snapshot snapshot = null;
                            Opt<Snapshot> snapshotOpt = record.getSnapshot();
                            if (snapshotOpt.isSome()) {
                                // make sure the delivered media package has valid URIs
                                snapshot = am.getHttpAssetProvider().prepareForDelivery(snapshotOpt.get());
                            }
                            return new ARecordImpl(record.getSnapshotId(), record.getMediaPackageId(), p, snapshot);
                        }
                    });
                }
            });
        }
    }
    final long searchTime = (System.nanoTime() - startTime) / 1000000;
    logger.debug("Complete query ms " + searchTime);
    return new AResultImpl(AbstractASelectQuery.<ARecord>vary(records), sizeOf(records), r.offset.getOr(0), r.limit.getOr(-1), searchTime);
}