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Cassandra support for Spring Data
/*
* Copyright 2016-2021 the original author or authors.
*
* 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
*
* https://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 org.springframework.data.cassandra.repository.query;
import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;
import java.util.List;
import org.reactivestreams.Publisher;
import org.springframework.core.convert.converter.Converter;
import org.springframework.dao.IncorrectResultSizeDataAccessException;
import org.springframework.data.cassandra.core.ReactiveCassandraOperations;
import org.springframework.data.cassandra.core.mapping.CassandraPersistentEntity;
import org.springframework.data.cassandra.core.mapping.CassandraPersistentProperty;
import org.springframework.data.cassandra.core.query.CassandraPageRequest;
import org.springframework.data.domain.Pageable;
import org.springframework.data.domain.Slice;
import org.springframework.data.domain.SliceImpl;
import org.springframework.data.mapping.context.MappingContext;
import org.springframework.data.mapping.model.EntityInstantiators;
import org.springframework.data.repository.query.ResultProcessor;
import org.springframework.data.repository.query.ReturnedType;
import org.springframework.data.util.ReflectionUtils;
import org.springframework.util.ClassUtils;
import com.datastax.oss.driver.api.core.cql.Row;
import com.datastax.oss.driver.api.core.cql.Statement;
/**
* Reactive query executions for Cassandra.
*
* @author Mark Paluch
* @since 2.0
*/
@FunctionalInterface
interface ReactiveCassandraQueryExecution {
Publisher execute(Statement statement, Class type);
/**
* {@link ReactiveCassandraQueryExecution} for a {@link org.springframework.data.domain.Slice}.
*
* @author Hleb Albau
* @author Mark Paluch
* @since 2.1
*/
final class SlicedExecution implements ReactiveCassandraQueryExecution {
private final ReactiveCassandraOperations operations;
private final Pageable pageable;
SlicedExecution(ReactiveCassandraOperations operations, Pageable pageable) {
this.operations = operations;
this.pageable = pageable;
}
/* (non-Javadoc)
* @see org.springframework.data.cassandra.repository.query.CassandraQueryExecution#execute(java.lang.String, java.lang.Class)
*/
@Override
public Publisher execute(Statement statement, Class type) {
CassandraPageRequest.validatePageable(pageable);
Statement statementToUse = statement.setPageSize(pageable.getPageSize());
if (pageable instanceof CassandraPageRequest) {
statementToUse = statementToUse.setPagingState(((CassandraPageRequest) pageable).getPagingState());
}
Mono> slice = operations.slice(statementToUse, type);
if (pageable.getSort().isUnsorted()) {
return slice;
}
return slice.map(it -> {
CassandraPageRequest cassandraPageRequest = (CassandraPageRequest) it.getPageable();
return new SliceImpl<>(it.getContent(), cassandraPageRequest.withSort(pageable.getSort()), it.hasNext());
});
}
}
/**
* {@link ReactiveCassandraQueryExecution} for collection returning queries.
*
* @author Mark Paluch
*/
final class CollectionExecution implements ReactiveCassandraQueryExecution {
private final ReactiveCassandraOperations operations;
CollectionExecution(ReactiveCassandraOperations operations) {
this.operations = operations;
}
/*
* (non-Javadoc)
* @see org.springframework.data.cassandra.repository.query.ReactiveCassandraQueryExecution#execute(java.lang.String, java.lang.Class)
*/
@Override
public Publisher execute(Statement statement, Class type) {
return operations.select(statement, type);
}
}
/**
* {@link ReactiveCassandraQueryExecution} to return a single entity.
*
* @author Mark Paluch
*/
final class SingleEntityExecution implements ReactiveCassandraQueryExecution {
private final ReactiveCassandraOperations operations;
private final boolean limiting;
SingleEntityExecution(ReactiveCassandraOperations operations, boolean limiting) {
this.operations = operations;
this.limiting = limiting;
}
/*
* (non-Javadoc)
* @see org.springframework.data.cassandra.repository.query.ReactiveCassandraQueryExecution#execute(java.lang.String, java.lang.Class)
*/
@Override
public Publisher execute(Statement statement, Class type) {
return operations.select(statement, type).buffer(2).handle((objects, sink) -> {
if (objects.isEmpty()) {
return;
}
if (objects.size() == 1 || limiting) {
sink.next(objects.get(0));
return;
}
sink.error(new IncorrectResultSizeDataAccessException(1, objects.size()));
});
}
}
/**
* {@link ReactiveCassandraQueryExecution} for an Exists query supporting count and regular row-data for exists
* calculation.
*
* @author Mark Paluch
* @since 2.1
*/
final class ExistsExecution implements ReactiveCassandraQueryExecution {
private final ReactiveCassandraOperations operations;
ExistsExecution(ReactiveCassandraOperations operations) {
this.operations = operations;
}
/* (non-Javadoc)
* @see org.springframework.data.cassandra.repository.query.ReactiveCassandraQueryExecution#execute(com.datastax.oss.driver.api.core.cql.Statement, java.lang.Class)
*/
@Override
public Publisher execute(Statement statement, Class type) {
Mono> rows = this.operations.select(statement, Row.class).buffer(2).next();
return rows.map(it -> {
if (it.isEmpty()) {
return false;
}
if (it.size() == 1) {
Row row = it.get(0);
if (ProjectionUtil.qualifiesAsCountProjection(row)) {
Object object = row.getObject(0);
return ((Number) object).longValue() > 0;
}
}
return true;
}).switchIfEmpty(Mono.just(false));
}
}
/**
* An {@link ReactiveCassandraQueryExecution} that wraps the results of the given delegate with the given result
* processing.
*
* @author Mark Paluch
*/
final class ResultProcessingExecution implements ReactiveCassandraQueryExecution {
private final ReactiveCassandraQueryExecution delegate;
private final Converter converter;
ResultProcessingExecution(ReactiveCassandraQueryExecution delegate, Converter converter) {
this.delegate = delegate;
this.converter = converter;
}
/*
* (non-Javadoc)
* @see org.springframework.data.cassandra.repository.query.ReactiveCassandraQueryExecution#execute(java.lang.String, java.lang.Class)
*/
@Override
public Publisher execute(Statement statement, Class type) {
return (Publisher) converter.convert(delegate.execute(statement, type));
}
}
/**
* A {@link Converter} to post-process all source objects using the given {@link ResultProcessor}.
*
* @author Mark Paluch
*/
final class ResultProcessingConverter implements Converter {
private final ResultProcessor processor;
private final MappingContext, CassandraPersistentProperty> mappingContext;
private final EntityInstantiators instantiators;
ResultProcessingConverter(ResultProcessor processor,
MappingContext, CassandraPersistentProperty> mappingContext,
EntityInstantiators instantiators) {
this.processor = processor;
this.mappingContext = mappingContext;
this.instantiators = instantiators;
}
/*
* (non-Javadoc)
* @see org.springframework.core.convert.converter.Converter#convert(java.lang.Object)
*/
@Override
public Object convert(Object source) {
ReturnedType returnedType = processor.getReturnedType();
if (ReflectionUtils.isVoid(returnedType.getReturnedType())) {
if (source instanceof Mono) {
return ((Mono) source).then();
}
if (source instanceof Publisher) {
return Flux.from((Publisher) source).then();
}
}
if (ClassUtils.isPrimitiveOrWrapper(returnedType.getReturnedType())) {
return source;
}
if (returnedType.isInstance(source)) {
return source;
}
Converter converter = new DtoInstantiatingConverter(returnedType.getReturnedType(),
mappingContext, instantiators);
return processor.processResult(source, converter);
}
}
}