Examples with PrefetchSelectQuery org.apache.cayenne.query.PrefetchSelectQuery used on opensource projects

Example 1 with PrefetchSelectQuery

use of org.apache.cayenne.query.PrefetchSelectQuery in project cayenne by apache.

the class DataDomainQueryAction method nextRows.

@Override
public void nextRows(Query query, List<?> dataRows) {
    // exclude prefetched rows in the main result
    if (prefetchResultsByPath != null && query instanceof PrefetchSelectQuery) {
        PrefetchSelectQuery prefetchQuery = (PrefetchSelectQuery) query;
        prefetchResultsByPath.put(prefetchQuery.getPrefetchPath(), dataRows);
    } else {
        fullResponse.addResultList(dataRows);
    }
}

Example 2 with PrefetchSelectQuery

use of org.apache.cayenne.query.PrefetchSelectQuery in project cayenne by apache.

the class DefaultSelectTranslator method appendQueryColumns.

/**
 * Appends columns needed for object SelectQuery to the provided columns
 * list.
 */
<T> List<ColumnDescriptor> appendQueryColumns(final List<ColumnDescriptor> columns, SelectQuery<T> query, ClassDescriptor descriptor, final String tableAlias) {
    final Set<ColumnTracker> attributes = new HashSet<>();
    // fetched attributes include attributes that are either:
    // 
    // * class properties
    // * PK
    // * FK used in relationship
    // * joined prefetch PK
    ObjEntity oe = descriptor.getEntity();
    PropertyVisitor visitor = new PropertyVisitor() {

        public boolean visitAttribute(AttributeProperty property) {
            ObjAttribute oa = property.getAttribute();
            resetJoinStack();
            Iterator<CayenneMapEntry> dbPathIterator = oa.getDbPathIterator();
            while (dbPathIterator.hasNext()) {
                Object pathPart = dbPathIterator.next();
                if (pathPart == null) {
                    throw new CayenneRuntimeException("ObjAttribute has no component: %s", oa.getName());
                } else if (pathPart instanceof DbRelationship) {
                    DbRelationship rel = (DbRelationship) pathPart;
                    dbRelationshipAdded(rel, JoinType.LEFT_OUTER, null);
                } else if (pathPart instanceof DbAttribute) {
                    DbAttribute dbAttr = (DbAttribute) pathPart;
                    appendColumn(columns, oa, dbAttr, attributes, null, tableAlias);
                }
            }
            return true;
        }

        public boolean visitToMany(ToManyProperty property) {
            visitRelationship(property);
            return true;
        }

        public boolean visitToOne(ToOneProperty property) {
            visitRelationship(property);
            return true;
        }

        private void visitRelationship(ArcProperty property) {
            resetJoinStack();
            ObjRelationship rel = property.getRelationship();
            DbRelationship dbRel = rel.getDbRelationships().get(0);
            List<DbJoin> joins = dbRel.getJoins();
            for (DbJoin join : joins) {
                DbAttribute src = join.getSource();
                appendColumn(columns, null, src, attributes, null, tableAlias);
            }
        }
    };
    descriptor.visitAllProperties(visitor);
    // stack should be reset, because all root table attributes go with "t0"
    // table alias
    resetJoinStack();
    // add remaining needed attrs from DbEntity
    DbEntity table = oe.getDbEntity();
    for (DbAttribute dba : table.getPrimaryKeys()) {
        appendColumn(columns, null, dba, attributes, null, tableAlias);
    }
    if (query instanceof PrefetchSelectQuery) {
        // for each relationship path add PK of the target entity...
        for (String path : ((PrefetchSelectQuery) query).getResultPaths()) {
            ASTDbPath pathExp = (ASTDbPath) oe.translateToDbPath(ExpressionFactory.exp(path));
            // add joins and find terminating element
            resetJoinStack();
            PathComponent<DbAttribute, DbRelationship> lastComponent = null;
            for (PathComponent<DbAttribute, DbRelationship> component : table.resolvePath(pathExp, getPathAliases())) {
                if (component.getRelationship() != null) {
                    // do not invoke dbRelationshipAdded(), invoke
                    // pushJoin() instead. This is to prevent
                    // 'forcingDistinct' flipping to true, that will result
                    // in unneeded extra processing and sometimes in invalid
                    // results (see CAY-1979). Distinctness of each row is
                    // guaranteed by the prefetch query semantics - we
                    // include target ID in the result columns
                    getJoinStack().pushJoin(component.getRelationship(), component.getJoinType(), null);
                }
                lastComponent = component;
            }
            // process terminating element
            if (lastComponent != null) {
                DbRelationship relationship = lastComponent.getRelationship();
                if (relationship != null) {
                    String labelPrefix = pathExp.getPath();
                    DbEntity targetEntity = relationship.getTargetEntity();
                    for (DbAttribute pk : targetEntity.getPrimaryKeys()) {
                        // note that we my select a source attribute, but
                        // label it as
                        // target for simplified snapshot processing
                        appendColumn(columns, null, pk, attributes, labelPrefix + '.' + pk.getName());
                    }
                }
            }
        }
    }
    // handle joint prefetches directly attached to this query...
    if (query.getPrefetchTree() != null) {
        // perform some sort of union or sub-queries.
        for (PrefetchTreeNode prefetch : query.getPrefetchTree().getChildren()) {
            prefetch.setEntityName(oe.getName());
        }
        for (PrefetchTreeNode prefetch : query.getPrefetchTree().adjacentJointNodes()) {
            // for each prefetch add all joins plus columns from the target
            // entity
            Expression prefetchExp = ExpressionFactory.exp(prefetch.getPath());
            ASTDbPath dbPrefetch = (ASTDbPath) oe.translateToDbPath(prefetchExp);
            resetJoinStack();
            DbRelationship r = null;
            for (PathComponent<DbAttribute, DbRelationship> component : table.resolvePath(dbPrefetch, getPathAliases())) {
                r = component.getRelationship();
                dbRelationshipAdded(r, JoinType.LEFT_OUTER, null);
            }
            if (r == null) {
                throw new CayenneRuntimeException("Invalid joint prefetch '%s' for entity: %s", prefetch, oe.getName());
            }
            // add columns from the target entity, including those that are matched
            // against the FK of the source entity.
            // This is needed to determine whether optional relationships are null
            // go via target OE to make sure that Java types are mapped correctly...
            ObjRelationship targetRel = (ObjRelationship) prefetchExp.evaluate(oe);
            ObjEntity targetEntity = targetRel.getTargetEntity();
            String labelPrefix = dbPrefetch.getPath();
            PropertyVisitor prefetchVisitor = new PropertyVisitor() {

                public boolean visitAttribute(AttributeProperty property) {
                    ObjAttribute oa = property.getAttribute();
                    Iterator<CayenneMapEntry> dbPathIterator = oa.getDbPathIterator();
                    while (dbPathIterator.hasNext()) {
                        Object pathPart = dbPathIterator.next();
                        if (pathPart == null) {
                            throw new CayenneRuntimeException("ObjAttribute has no component: %s", oa.getName());
                        } else if (pathPart instanceof DbRelationship) {
                            DbRelationship rel = (DbRelationship) pathPart;
                            dbRelationshipAdded(rel, JoinType.INNER, null);
                        } else if (pathPart instanceof DbAttribute) {
                            DbAttribute dbAttr = (DbAttribute) pathPart;
                            appendColumn(columns, oa, dbAttr, attributes, labelPrefix + '.' + dbAttr.getName());
                        }
                    }
                    return true;
                }

                public boolean visitToMany(ToManyProperty property) {
                    return true;
                }

                public boolean visitToOne(ToOneProperty property) {
                    return true;
                }
            };
            ClassDescriptor prefetchClassDescriptor = entityResolver.getClassDescriptor(targetEntity.getName());
            prefetchClassDescriptor.visitAllProperties(prefetchVisitor);
            // append remaining target attributes such as keys
            DbEntity targetDbEntity = r.getTargetEntity();
            for (DbAttribute attribute : targetDbEntity.getAttributes()) {
                appendColumn(columns, null, attribute, attributes, labelPrefix + '.' + attribute.getName());
            }
        }
    }
    return columns;
}