求 关于直接用数据库里node间的关系,return一段json的具体操作例子
大家好,Neo4j新手,想问一个问题。 我想基于现有的数据关系,做一下细则的分类在json中,最后直接用query return一段json出来,这样可行吗? 网上查了一下感觉例子不是特别的多,希望做过类似 或者了解的大佬分享一点example给我学习一下,或者给我点方向。 自己在网上看了好像是可以用到unwind, merge这样的方法。可是有点复杂不知道具体如何最后把想要的东西给return出来。 非常感谢!
4 回复
你的问题是,需要从NEO4J查询数据,然后直接返回JSON数据对吧?这样的话你可以直接使用rest api查询数据,然后根据rest api返回的数据格式,单独写一个数据封装的工具,这样你就可以直接使用java driver直接查询出json数据了。下面是一个参考:
package casia.isi.neo4j.driver;
import casia.isi.neo4j.common.CRUD;
import casia.isi.neo4j.common.TimeUnit;
import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONArray;
import com.alibaba.fastjson.JSONObject;
import org.apache.log4j.Logger;
import org.neo4j.driver.internal.value.*;
import org.neo4j.driver.v1.*;
import org.neo4j.driver.v1.types.Node;
import org.neo4j.driver.v1.types.Path;
import org.neo4j.driver.v1.types.Relationship;
import org.neo4j.driver.v1.util.Pair;
import java.util.List;
import java.util.Map;
public class Neo4jDriver {
/**
* JAVA_DRIVER返回的数据格式统一按照D3_GRAPH格式返回
**/
private final static Logger logger = org.apache.log4j.Logger.getLogger(Neo4jDriver.class);
/**
* @param driver:传入NEO4J_JAVA驱动
* @param statement:cypher
* @return
* [@Description](/user/Description): TODO(构图导入等操作访问)
*/
public synchronized static JSONObject composer(Driver driver, String statement) {
long startMill = System.currentTimeMillis();
boolean flag = false;
// RETRY FAILURE QUERY
while (!flag) {
try (Session session = driver.session()) {
try (Transaction tx = session.beginTransaction()) {
tx.run(statement);
tx.success(); // Mark this write as successful.
flag = true;
}
} catch (Exception e) {
logger.info("Retrying query " + statement);
}
}
long stopMill = System.currentTimeMillis();
long consume = (stopMill - startMill) / Integer.parseInt(String.valueOf(TimeUnit.MILL_SECOND_CV.getSymbolValue()));
if (consume != 0) {
logger.info("Neo4j driver composer success!consume:" + consume + "s");
} else {
logger.info("Neo4j driver composer success!consume:" + (stopMill - startMill) + "mills");
}
return new JSONObject();
}
/**
* @param driver:传入NEO4J_JAVA驱动
* @param statement:cypher
* @return
* [@Description](/user/Description): TODO(构图导入等操作访问)
*/
public synchronized static JSONObject composerReturnNodeId(Driver driver, String statement) {
JSONObject resultMessage = new JSONObject();
long startMill = System.currentTimeMillis();
try (Session session = driver.session()) {
try (Transaction tx = session.beginTransaction()) {
StatementResult result = tx.run(statement);
while (result.hasNext()) {
Record record = result.next();
Map<String, Object> map = record.asMap();
JSONObject object = JSONObject.parseObject(JSON.toJSONString(map));
resultMessage.putAll(object);
}
tx.success(); // Mark this write as successful.
}
} catch (Exception e) {
e.printStackTrace();
}
long stopMill = System.currentTimeMillis();
long consume = (stopMill - startMill) / Integer.parseInt(String.valueOf(TimeUnit.MILL_SECOND_CV.getSymbolValue()));
if (consume != 0) {
logger.info("Neo4j merge composer success!consume:" + consume + "s");
} else {
logger.info("Neo4j merge composer success!consume:" + (stopMill - startMill) + "mills");
}
return resultMessage;
}
/**
* @param driver:传入NEO4J_JAVA驱动
* @param statement:cypher
* @return
* [@Description](/user/Description): TODO(构图导入等操作访问)
*/
public synchronized static JSONObject composerAutoCommit(Driver driver, String statement) {
long startMill = System.currentTimeMillis();
try (Session session = driver.session()) {
/**
* AUTO COMMIT TRANSACTION
* **/
session.run(statement);
} catch (Exception e) {
e.printStackTrace();
}
long stopMill = System.currentTimeMillis();
long consume = (stopMill - startMill) / Integer.parseInt(String.valueOf(TimeUnit.MILL_SECOND_CV.getSymbolValue()));
logger.info("Neo4j driver composer auto commit success!consume:" + consume + "s");
return new JSONObject();
}
public static JSONObject rowProperties(Driver driver, String cypher) {
JSONObject resultObject = new JSONObject();
JSONArray resultArray = new JSONArray();
try (Session session = driver.session()) {
StatementResult result = session.run(cypher);
while (result.hasNext()) {
Record record = result.next();
Map<String, Object> map = record.asMap();
JSONObject object = JSONObject.parseObject(JSON.toJSONString(map));
resultArray.add(object);
}
} catch (Exception e) {
e.printStackTrace();
}
resultObject.put(CRUD.RETRIEVE_PROPERTIES.getSymbolValue(), resultArray);
return resultObject;
}
/**
* @param driver:传入NEO4J_JAVA驱动
* @param statement:cypher
* @return
* [@Description](/user/Description): TODO(检索)
*/
public static JSONObject searcher(Driver driver, String statement) {
long startMill = System.currentTimeMillis();
JSONObject results = new JSONObject();
JSONArray resultArray = new JSONArray();
JSONObject arrayObject = new JSONObject();
JSONArray columns = new JSONArray();
JSONArray data = new JSONArray();
JSONObject dataObject = new JSONObject();
JSONObject graph = new JSONObject();
JSONArray relationships = new JSONArray();
JSONArray nodes = new JSONArray();
JSONArray properties = new JSONArray();
try (Session session = driver.session()) {
// Auto-commit transactions are a quick and easy way to wrap a read.
StatementResult result = session.run(statement);
// Each Cypher execution returns a stream of records.
while (result.hasNext()) {
Record record = result.next();
// Values can be extracted from a record by index or name.
List<Pair<String, Value>> list = record.fields();
JSONObject propertiesPack = new JSONObject();
for (int i = 0; i < list.size(); i++) {
Pair<String, Value> stringValuePair = list.get(i);
if (!columns.contains(stringValuePair.key())) {
columns.add(stringValuePair.key());
}
Value value = stringValuePair.value();
if (value instanceof NodeValue) {
JSONObject objectNode = packNode(value.asNode());
if (!nodes.contains(objectNode)) nodes.add(objectNode);
} else if (value instanceof PathValue) {
JSONArray objectNodes = packNodeByPath(value.asPath());
objectNodes.forEach(node -> {
JSONObject nodeObj = (JSONObject) node;
if (!nodes.contains(nodeObj)) nodes.add(nodeObj);
});
JSONArray objectRelas = packRelations(value.asPath());
objectRelas.forEach(relation -> {
JSONObject relationObj = (JSONObject) relation;
if (!relationships.contains(relationObj)) relationships.add(relationObj);
});
} else {
propertiesPack.putAll(packStringValuePair(stringValuePair));
}
}
if (!propertiesPack.isEmpty()) properties.add(propertiesPack);
}
} catch (Exception e) {
e.printStackTrace();
}
graph.put("relationships", relationships);
graph.put("nodes", nodes);
graph.put("properties", properties);
dataObject.put("graph", graph);
data.add(dataObject);
arrayObject.put("data", data);
arrayObject.put("columns", columns);
resultArray.add(arrayObject);
results.put("results", resultArray);
results.put("totalNodeSize", nodes.size());
results.put("totalRelationSize", relationships.size());
long stopMill = System.currentTimeMillis();
long consume = (stopMill - startMill) / Integer.parseInt(String.valueOf(TimeUnit.MILL_SECOND_CV.getSymbolValue()));
logger.info("Neo4j driver searcher success!consume:" + consume + "s");
return results;
}
private static JSONObject packStringValuePair(Pair<String, Value> stringValuePair) {
String key = stringValuePair.key();
Value value = stringValuePair.value();
JSONObject object = new JSONObject();
if (value instanceof BooleanValue) {
object.put(key, value.asBoolean());
} else if (value instanceof FloatValue) {
object.put(key, value.asFloat());
} else if (value instanceof IntegerValue) {
// object.put(key, value.asInt());
object.put(key, value.asLong());
} else if (value instanceof ListValue) {
object.put(key, value.asList());
} else {
object.put(key, value.asString());
}
return object;
}
private static JSONArray packRelations(Path path) {
JSONArray arrayRelations = new JSONArray();
for (Relationship relationship : path.relationships()) {
arrayRelations.add(packRelation(relationship));
}
return arrayRelations;
}
private static JSONObject packRelation(Relationship relationship) {
JSONObject currentRelation = new JSONObject();
currentRelation.put("startNode", relationship.startNodeId());
currentRelation.put("id", relationship.id());
currentRelation.put("type", relationship.type());
currentRelation.put("endNode", relationship.endNodeId());
currentRelation.put("properties", JSONObject.parseObject(JSON.toJSONString(relationship.asMap())));
return currentRelation;
}
private static JSONArray packNodeByPath(Path path) {
JSONArray pathNodes = new JSONArray();
for (Node node : path.nodes()) {
pathNodes.add(packNode(node));
}
return pathNodes;
}
private static JSONObject packNode(Node node) {
JSONObject currentNode = new JSONObject();
currentNode.put("id", node.id());
currentNode.put("properties", JSONObject.parseObject(JSON.toJSONString(node.asMap())));
currentNode.put("labels", JSONArray.parseArray(JSON.toJSONString(node.labels())));
return currentNode;
}
}
下面这些是JSON的生成方式,你可以试试,不知道满不满足你的需求:)
// 1、数据导出为JSON文件,生成的JSON在neo4j安装目录下的import目录下:
CALL apoc.export.json.query('match (n) return n limit 10','test.json')
// 2、将整个库导出到指定的JSON文件
CALL apoc.export.json.all('all.json',null)
// 3、将指定的节点和关系导出到指定的JSON文件
MATCH (nod)
MATCH ()-[reels]->()
WITH collect(nod) as node, collect(reels) as rels
CALL apoc.export.json.data(node, rels, {file}, null)
YIELD nodes, relationships, properties, file, source,format, time
RETURN *
// 4、导出图对象
CALL apoc.graph.fromDB('test',{}) yield graph
CALL apoc.export.json.graph(graph, 'garph.json')
YIELD nodes, relationships, properties, file, source,format, time
RETURN *
// 5、给节点n设置json属性
CREATE (n) WITH n CALL apoc.convert.setJsonProperty(n, 'json', [1,2,3]) RETURN n
安装额外的插件,下载插件安装到plugin目录下 使用插件生成JSON-从CYPHER直接生成JSON【支持节点转换/属性转换/路径转换】
match (n) return casia.convert.json(n) limit 10
match p=(n)--() return casia.convert.json(p) limit 1
match (n) return casia.convert.json(properties(n)) limit 10
@crazyyanchao 谢谢你,其实我不是纠结在导出JSON文件,我是要直接导出的东西是json格式,然后里面有个嵌套,所以比较复杂。好像是要用到unwind,但是我不是很会用,想看看这方面的例子。