Develop Reference

How to use JCypher to send unrelated queries in one go and get the results properly

I'm using JCypher 4.2.0 with Neo4J Server 4.0.2 with the builtin Movie graph.
I'm trying to unite couple simple, independent queries to one bigger for my needs.
first query: MATCH (people:Person) RETURN people.name, second query: MATCH (m:Movie) WHERE m.title = "Apollo 13" RETURN m.title.
and in JCypher:
JcNode
people = new JcNode("people"),
m = new JcNode("m");
JcQuery
query1 = new JcQuery(new IClause[]{
MATCH.node(people).label("Person"),
RETURN.value(people.property("name"))
}),
query2 = new JcQuery(new IClause[]{
MATCH.node(m).label("Movie"),
WHERE.valueOf(m.property("title")).EQUALS("Apollo 13")
RETURN.value(m.property("title"))
});
Of course, m.title should return only 1 result.
is it possible?

SpagoBI multi value parameter

I'm trying to create a multi-value parameter in SpagoBI.
Here is my data set query whose last line appears to be causing an issue.
select C."CUSTOMERNAME", C."CITY", D."YEAR", P."NAME"
from "CUSTOMER" C, "DAY" D, "PRODUCT" P, "TRANSACTIONS" T
where C."CUSTOMERID" = T."CUSTOMERID"
and D."DAYID" = T."DAYID"
and P."PRODUCTID" = T."PRODUCTID"
and _CITY_
I created before open script in my dataset which looks like this:
this.queryText = this.queryText.replace(_CITY_, " CUSTOMER.CITY in ( "+params["cp"].value+" ) ");
My parameter is set as string, display type dynamic list box.
When I run the report I'm getting that error.
org.eclipse.birt.report.engine.api.EngineException: There are errors evaluating script "
this.queryText = this.queryText.replace(_CITY_, " CUSTOMER.CITY in ( "+params["cp"].value+" ) ");
":
Fail to execute script in function __bm_beforeOpen(). Source:
Could anyone please help me?

Hello I managed to solve the problem. Here is my code:
var substring = "" ;
var strParamValsSelected=reportContext.getParameterValue("citytext");
substring += "?," + strParamValsSelected ;
this.queryText = this.queryText.replace("'xxx'",substring);
As You can see the "?" is necessary before my parameter. Maybe It will help somebody. Thank You so much for Your comments.

If you are using SpagoBI server and High charts (JFreeChart Engine) / JSChat Engine you can just use ($P{param_url}) in query,
or build dynamic query using Java script / groovy Script
so your query could also be:
select C."CUSTOMERNAME", C."CITY", D."YEAR", P."NAME"
from "CUSTOMER" C, "DAY" D, "PRODUCT" P, "TRANSACTIONS" T
where C."CUSTOMERID" = T."CUSTOMERID"
and D."DAYID" = T."DAYID"
and P."PRODUCTID" = T."PRODUCTID"
and CUSTOMER."CITY" in ('$P{param_url}')

Neo4j ExecutionEngine does not return valid results

Trying to use a similar example from the sample code found here
My sample function is:
void query()
{
String nodeResult = "";
String rows = "";
String resultString;
String columnsString;
System.out.println("In query");
// START SNIPPET: execute
ExecutionEngine engine = new ExecutionEngine( graphDb );
ExecutionResult result;
try ( Transaction ignored = graphDb.beginTx() )
{
result = engine.execute( "start n=node(*) where n.Name =~ '.*79.*' return n, n.Name" );
// END SNIPPET: execute
// START SNIPPET: items
Iterator<Node> n_column = result.columnAs( "n" );
for ( Node node : IteratorUtil.asIterable( n_column ) )
{
// note: we're grabbing the name property from the node,
// not from the n.name in this case.
nodeResult = node + ": " + node.getProperty( "Name" );
System.out.println("In for loop");
System.out.println(nodeResult);
}
// END SNIPPET: items
// START SNIPPET: columns
List<String> columns = result.columns();
// END SNIPPET: columns
// the result is now empty, get a new one
result = engine.execute( "start n=node(*) where n.Name =~ '.*79.*' return n, n.Name" );
// START SNIPPET: rows
for ( Map<String, Object> row : result )
{
for ( Entry<String, Object> column : row.entrySet() )
{
rows += column.getKey() + ": " + column.getValue() + "; ";
System.out.println("nested");
}
rows += "\n";
}
// END SNIPPET: rows
resultString = engine.execute( "start n=node(*) where n.Name =~ '.*79.*' return n.Name" ).dumpToString();
columnsString = columns.toString();
System.out.println(rows);
System.out.println(resultString);
System.out.println(columnsString);
System.out.println("leaving");
}
}
When I run this in the web console I get many results (as there are multiple nodes that have an attribute of Name that contains the pattern 79. Yet running this code returns no results. The debug print statements 'in loop' and 'nested' never print either. Thus this must mean there are not results found in the Iterator, yet that doesn't make sense.
And yes, I already checked and made sure that the graphDb variable is the same as the path for the web console. I have other code earlier that uses the same variable to write to the database.
EDIT - More info
If I place the contents of query in the same function that creates my data, I get the correct results. If I run the query by itself it returns nothing. It's almost as the query works only in the instance where I add the data and not if I come back to the database cold in a separate instance.
EDIT2 -
Here is a snippet of code that shows the bigger context of how it is being called and sharing the same DBHandle
package ContextEngine;
import ContextEngine.NeoHandle;
import java.util.LinkedList;
/*
* Class to handle streaming data from any coded source
*/
public class Streamer {
private NeoHandle myHandle;
private String contextType;
Streamer()
{
}
public void openStream(String contextType)
{
myHandle = new NeoHandle();
myHandle.createDb();
}
public void streamInput(String dataLine)
{
Context context = new Context();
/*
* get database instance
* write to database
* check for errors
* report errors & success
*/
System.out.println(dataLine);
//apply rules to data (make ContextRules do this, send type and string of data)
ContextRules contextRules = new ContextRules();
context = contextRules.processContextRules("Calls", dataLine);
//write data (using linked list from contextRules)
NeoProcessor processor = new NeoProcessor(myHandle);
processor.processContextData(context);
}
public void runQuery()
{
NeoProcessor processor = new NeoProcessor(myHandle);
processor.query();
}
public void closeStream()
{
/*
* close database instance
*/
myHandle.shutDown();
}
}
Now, if I call streamInput AND query in in the same instance (parent calls) the query returns results. If I only call query and do not enter ANY data in that instance (yet web console shows data for same query) I get nothing. Why would I have to create the Nodes and enter them into the database at runtime just to return a valid query. Shouldn't I ALWAYS get the same results with such a query?

You mention that you are using the Neo4j Browser, which comes with Neo4j. However, the example you posted is for Neo4j Embedded, which is the in-process version of Neo4j. Are you sure you are talking to the same database when you try your query in the Browser?
In order to talk to Neo4j Server from Java, I'd recommend looking at the Neo4j JDBC driver, which has good support for connecting to the Neo4j server from Java.
http://www.neo4j.org/develop/tools/jdbc
You can set up a simple connection by adding the Neo4j JDBC jar to your classpath, available here: https://github.com/neo4j-contrib/neo4j-jdbc/releases Then just use Neo4j as any JDBC driver:
Connection conn = DriverManager.getConnection("jdbc:neo4j://localhost:7474/");
ResultSet rs = conn.executeQuery("start n=node({id}) return id(n) as id", map("id", id));
while(rs.next()) {
System.out.println(rs.getLong("id"));
}
Refer to the JDBC documentation for more advanced usage.
To answer your question on why the data is not durably stored, it may be one of many reasons. I would attempt to incrementally scale back the complexity of the code to try and locate the culprit. For instance, until you've found your problem, do these one at a time:
Instead of looping through the result, print it using System.out.println(result.dumpToString());
Instead of the regex query, try just MATCH (n) RETURN n, to return all data in the database
Make sure the data you are seeing in the browser is not "old" data inserted earlier on, but really is an insert from your latest run of the Java program. You can verify this by deleting the data via the browser before running the Java program using MATCH (n) OPTIONAL MATCH (n)-[r]->() DELETE n,r;
Make sure you are actually working against the same database directories. You can verify this by leaving the server running. If you can still start your java program, unless your Java program is using the Neo4j REST Bindings, you are not using the same directory. Two Neo4j databases cannot run against the same database directory simultaneously.

Exception using QueryEngine inside a Transaction

I'm using the neo4j 1.9.M01 version with the java-rest-binding 1.8.M07, and I have a problem with this code that aims to get a node from a neo4j database with the property "URL" that is "ARREL", using the Query language via rest. The problems seems to happens only inside a transaction, throwing an exception, but otherwise works well :
RestGraphDatabase graphDb = new RestGraphDatabase("http://localhost:7474/db/data");
RestCypherQueryEngine queryEngine = new RestCypherQueryEngine(graphDb.getRestAPI());
Node nodearrel = null;
Transaction tx0 = gds.beginTx();
try{
final String queryStringarrel = ("START n=node(*) WHERE n.URL =~{URL} RETURN n");
QueryResult<Map<String, Object>> retornar = queryEngine.query(queryStringarrel, MapUtil.map("URL","ARREL"));
for (Map<String,Object> row : retornar)
{
nodearrel = (Node)row.get("n");
System.out.println("Arrel: "+nodearrel.getProperty("URL")+" id : "+nodearrel.getId());
}
tx0.success();
}
(...)
But an exception happens: *exception tx0: Error reading as JSON ''
* every execution at the line that returns the QueryResult object.
I also have tried to do it with the ExecutionEngine (between a transaction):
ExecutionEngine engine = new ExecutionEngine( graphDb );
String ARREL = "ARREL";
ExecutionResult result = engine.execute("START n=node(*) WHERE n.URL =~{"+ARREL+"} RETURN n");
Iterator<Node> n_column = result.columnAs("n");
Node arrelat = (Node) n_column.next();
for ( Node node : IteratorUtil.asIterable( n_column ) )
(...)
But it also fails at the *n_column.next()* returning a null object that throws an exception.
The problem is that I need to use the transactions to optimize the queries due if not it take too much time processing all the queries that I need to do. Should I try to join several operations to the query, to avoid using the transactions?

try to add single quotes at:
START n=node(*) WHERE n.URL =~ '{URL}' RETURN n

Can you update your java-rest-binding to the latest version (1.8) ? In between we had a version that automatically applied REST-batch-operations to places with transaction semantics.
So the transactions you see are not real transactions but just recording your operations to be executed as batch-rest-operations on tx.success/finish
Execute the queries within the transaction, but only access the results after the tx is finished. Then your results will be there.
This is for instance useful to send many cypher queries in one go to the server and have the results available all in one go afterwards.
And yes #ulkas use parameters but not like that:
START n=node(*) WHERE n.URL =~ {URL} RETURN n
params: { "URL" : "http://your.url" }
No quotes neccessary when using params, just like SQL prepared statements.

How can I do this inner join properly in Apache PIG?

I have two files, one called a-records
123^record1
222^record2
333^record3
and the other file called b-records
123^jim
123^jim
222^mike
333^joe
you can see in file A that I have the token 123 one time. In file B it's in there twice. Is there a way using Apache PIG I can join the data such that I only get ONE joined record from the A file?
here is my current script which outputs the following below
arecords = LOAD '$a' USING PigStorage('^') as (token:chararray, type:chararray);
brecords = LOAD '$b' USING PigStorage('^') as (token:chararray, name:chararray);
x = JOIN arecords BY token, brecords BY token;
dump x;
which yields:
(123,record1,123,jim)
(123,record1,123,jim)
(222,record2,222,mike)
(333,record3,333,joe)
when what I REALLY want is(notice token 123 is only in there once after the join)
(123,record1,123,jim)
(222,record2,222,mike)
(333,record3,333,joe)
any ideas? thanks so much

I would do something like this :
arecords = LOAD '$a' USING PigStorage('^') as (token:chararray, type:chararray);
brecords = LOAD '$b' USING PigStorage('^') as (token:chararray, name:chararray);
bdistinct = DISTINCT brecords;
x = JOIN arecords BY token, bdistinct BY token;
dump x;