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/*
* Copyright (c) "Neo4j"
* Neo4j Sweden AB [https://neo4j.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 org.neo4j.driver;
import java.util.Map;
/**
* Common interface for components that can execute Neo4j queries.
* Important notes on semantics
*
* queries run in the same {@link QueryRunner} are guaranteed to execute in order, meaning changes made by one query will be seen by all subsequent queries in
* the same {@link QueryRunner}.
*
* However, to allow handling very large results, and to improve performance, result streams are retrieved lazily from the network. This means that when any of
* {@link #run(Query)} methods return a result, the query has only started executing - it may not have completed yet. Most of the time, you will not notice
* this, because the driver automatically waits for queries to complete at specific points to fulfill its contracts.
*
* Specifically, the driver will ensure all outstanding queries are completed whenever you:
*
*
* - Read from or discard a result, for instance via
* {@link Result#next()} or {@link Result#consume()}
* - Explicitly commit/rollback a transaction using blocking {@link Transaction#close()}
* - Close a session using blocking {@link Session#close()}
*
*
* As noted, most of the time, you will not need to consider this - your writes will
* always be durably stored as long as you either use the results, explicitly commit
* {@link Transaction transactions} or close the session you utilised using {@link Session#close()}.
*
* While these semantics introduce some complexity, it gives the driver the ability
* to handle infinite result streams (like subscribing to events), significantly lowers
* the memory overhead for your application and improves performance.
*
* @see Session
* @see Transaction
* @since 5.0
*/
public interface SimpleQueryRunner {
/**
* Run a query and return a result stream.
*
* This method takes a set of parameters that will be injected into the query by Neo4j. Using parameters is highly encouraged, it helps avoid dangerous
* cypher injection attacks and improves database performance as Neo4j can re-use query plans more often.
*
* This particular method takes a {@link Value} as its input. This is useful if you want to take a map-like value that you've gotten from a prior result and
* send it back as parameters.
*
* If you are creating parameters programmatically, {@link #run(String, Map)} might be more helpful, it converts your map to a {@link Value} for you.
*
Example
*
* {@code
*
* Result result = session.run( "MATCH (n) WHERE n.name = $myNameParam RETURN (n)",
* Values.parameters( "myNameParam", "Bob" ) );
* }
*
*
* @param query text of a Neo4j query
* @param parameters input parameters, should be a map Value, see {@link Values#parameters(Object...)}.
* @return a stream of result values and associated metadata
*/
Result run(String query, Value parameters);
/**
* Run a query and return a result stream.
*
* This method takes a set of parameters that will be injected into the query by Neo4j. Using parameters is highly encouraged, it helps avoid dangerous
* cypher injection attacks and improves database performance as Neo4j can re-use query plans more often.
*
* This version of run takes a {@link Map} of parameters. The values in the map must be values that can be converted to Neo4j types. See {@link
* Values#parameters(Object...)} for a list of allowed types.
*
Example
*
* {@code
*
* Map parameters = new HashMap();
* parameters.put("myNameParam", "Bob");
*
* Result result = session.run( "MATCH (n) WHERE n.name = $myNameParam RETURN (n)",
* parameters );
* }
*
*
* @param query text of a Neo4j query
* @param parameters input data for the query
* @return a stream of result values and associated metadata
*/
Result run(String query, Map parameters);
/**
* Run a query and return a result stream.
*
* This method takes a set of parameters that will be injected into the query by Neo4j. Using parameters is highly encouraged, it helps avoid dangerous
* cypher injection attacks and improves database performance as Neo4j can re-use query plans more often.
*
* This version of run takes a {@link Record} of parameters, which can be useful if you want to use the output of one query as input for another.
*
* @param query text of a Neo4j query
* @param parameters input data for the query
* @return a stream of result values and associated metadata
*/
Result run(String query, Record parameters);
/**
* Run a query and return a result stream.
*
* @param query text of a Neo4j query
* @return a stream of result values and associated metadata
*/
Result run(String query);
/**
* Run a query and return a result stream.
*
Example
*
* {@code
*
* Query query = new Query( "MATCH (n) WHERE n.name = $myNameParam RETURN n.age" );
* Result result = session.run( query.withParameters( Values.parameters( "myNameParam", "Bob" ) ) );
* }
*
*
* @param query a Neo4j query
* @return a stream of result values and associated metadata
*/
Result run(Query query);
}