I'm using neo4j 1.7 through the REST interface, and I punched in the following query:
{"script": "g.v(1).aggregate(x); g.V.except(x)", "params": {"x":[]}}
which should return the list, missing Node 1, but instead this returns the entire list of Nodes. I've looked over the neo4j documentation and see examples of using variables, but this query does not seem to behave as exepected.
Has anyone else run into this problem or is this something can't/shouldn't be done through the gremlin REST interface?
When you're not in the Gremlin REPL, you need to manually iterate expressions when it's not the last expression returned (the Gremlin Plugin automatically iterates the last expression):
g.v(1).aggregate(x).iterate(); g.V.except(x)
But you can simplify it down to one statement like this:
g.V.except([g.v(1)])
Related
I will apologise right at the outset as I am sure my question is elementary! I am not a database man but I have an idea and only a graph database is going to do it - so i am learning right from the very beginning. I am using Neo4j 2.3 and building the blocks of my structure in org charts which I then convert into Excel - I am comfortable with Excel, I am an Engineer!
I use CONCATENATE within Excel to build my Cypher statements and generating the nodes works perfectly, so far so good.
I then used the same technique to build the Cypher statements for the relationships and when I trialled it using a single Cypher Statement the relationship loads perfectly but when I try a set of statements I get a message saying that I need WITH between MATCH and MERGE.
I have read up the stuff about WITH and I can see that I am mixing read and write statements without separating them properly, I can also see that aliasing comes into it - but for the life of me I can't see how to deal with it!
The first sheet looks like this and this generates the nodes nicely:
:
The second sheet - for the relationships, looks like this:
Any help at all would be much appreciated!
Each of the statements your second sheet generates could be executed independently, since you don't reference any of the aliases from previous lines.
Or you could add a WITH to the end of each statement, clearing out the aliases in scope:
MATCH (a1{id:470}), (b1: {id: 48}) MERGE (a1)-[:HAS_ROD_ASSY]->(b1) WITH NULL AS _
MATCH (a2 {id:463}), (b2: {id: 584}) MERGE (a2)-[:ROD_FEATURES]->(b2) WITH NULL AS _
...
LOAD CSV
However, you might find the LOAD CSV functionality in Cypher easier to work with.
I have a graph database (Neo4j) in which I configured a property to be auto indexed with full-text. Everything is working great except that I have 1 row that is not returned when I execute a particular cypher query.
My property in the graph equals (I've put in bold the words I am using in my cypher query):
1pizzeriadeicomparipourlesamateursdevraiespizzasitaliennescestadireavecpastropdepateetcuitesaufeudeboislaplacenepayepasdeminesalleettablesassezpetitesetilfautsarmerdepatiencelessamedisoirssionnapasreserveenv15minutesdattentemaislespizzassontexcellentesrestaurantmontrealmontrealquebeccanada5148435411
If I execute the following cypher query:
START n1=NODE:node_auto_index('Search_Field:*res* AND Search_Field:*taurant* AND Search_Field:*411*')
RETURN n1.Search_Field
My row is returned!
So far no problem!
But when I execute it by putting the word « restaurant » all together like this:
START n1=NODE:node_auto_index('Search_Field:*restaurant* AND Search_Field:*411*')
RETURN n1.Search_Field
Then no rows are returned.
I tested a lot of stuffs in order to understand and try to find a pattern or something that can explain the problem. It seems like the length of my property value might play a role. I know it sounds strange but if I add 3 or more letters, let say « aaa », after the word restaurant in the property value, like this (look at the bold letters close to the end of the value):
1pizzeriadeicomparipourlesamateursdevraiespizzasitaliennescestadireavecpastropdepateetcuitesaufeudeboislaplacenepayepasdeminesalleettablesassezpetitesetilfautsarmerdepatiencelessamedisoirssionnapasreserveenv15minutesdattentemaislespizzassontexcellentesrestaurantaaamontrealmontrealquebeccanada5148435411
then, if I execute the same cypher query, the row is now returned.
Anyone had encountered similar problems! It's driving me crazy!
I have tested on both Neo4j-enterprise 2.2.1 and the latest Community 3.0.0-M02. Same result with both of them.
Any idea on where or what should I look for ?
The query term get passed through the lucene analyzer - just like the contents you index. I'm not 100% sure but I think that the default analyzer "eats up" the digits, that's why you don't get the results.
You can supply an analyzer class when the index is created for the first time. Also you can use Java API to query the index - this allows to pass in instances of Lucene Query, see my example at http://blog.armbruster-it.de/2014/10/deep-dive-on-fulltext-indexing-with-neo4j/.
TL,DR: I need a query which gives me all nodes/relationships which contain a certain value (in my case a string, so much I know), without knowing which property(key) contains the string. I am using neo4j(latest version), meteor (latest version) and the meteor neo4j driver, which is recommended on the neo4j website for meteor.
Currently I am working (as part of my bachelor thesis) on a tool to visualize the output of any Cypher query on any database, regardless of the database contents.
So far I've managed to correctly display nodes/relationships which are coming out. My problem now is to visualize (get nodes and relationships to feed into my frontend) textual queries like (taken from the neo4j movie database, which I am using for development)
MATCH (tom:Person {name:"Tom Hanks"})-[:ACTED_IN]->(m)<-[:ACTED_IN]-(coActors)
RETURN coActors.name
This kind of queries only returns an array of strings and not whole nodes or relationships. I now need some way (preferably a Cypher query) to get all nodes which contain for example the string "Audrey Tatou".
The problem I've now run into is that I didn't find a way to write a query which doesn't need something like
MATCH n
WHERE Person.name = "some name"
Since I don't know anything about the contents of the database I cannot use
WHERE propertyName = "propertyValue"
since I only know the value but not the name of the property.
The only solution here will be to get every nodes with your label and check properties and values using reflection on client side.
Using cypher, the solution would be to get all properties and their values and parse their values using a foreach loop. Maybe you can do this, but I'm really not sure, it's a recent feature but you can still give a try.
Here is what I found for the cypher solution: How can I return all properties for a node using Cypher?
So, you have query that returns array of string.
In fact - you can receive almost anything as result. Cypher is capable to return just bare strings, that are not related to anything.
Long story short - you can't vizualize this data, because of this data nature. Best you can do is to represent them as table (or similar), like Neo4j browser do this.
But, there is (probably) solution for you. Neo4j has feature called Legacy indexing. And there you can find full text indexes. Maybe this can help you.
You can just use a driver that returns nodes and rels, or if you do the queries manually add resultDataContents entry
{statements:[{statement:"MATCH ..","resultDataContents",["graph"]}]}
to your payload and you get nodes and relationships back.
I'm trying to pile a load of Twitter data into Neo4J using the .Net Neo4JClient. It's essentially the same type of Twitter user data for each node, but some of the nodes have a different significance to others, hence I would like to label them differently.
(I'm brand new both to Neo4J and the client, too).
So I've been trying to label them like so:
var query = _client.Cypher
.Create("(primaryNode:nodeLabel {twitterUser})")
.WithParams(new { nodeLabel = "nodeType", twitterUser } );
query.ExecuteWithoutResults();
Note: I split out the ExecuteWithoutResults so I could debug the query, and it is registering the parameters OK. The documentation here:
https://github.com/Readify/Neo4jClient/wiki/cypher#explicit-parameters
... suggests that parameters can be created "at any point in the fluent query" - but the Neo documentation about parameters here:
http://docs.neo4j.org/chunked/1.8.2/cypher-parameters.html
... kind of suggests otherwise, that parameters are specifically for things like WHERE clauses, indexes and relationship Ids.
Anyway - when I execute the above, I get a shiny new node with the label "nodeLabel" - so the parameter ain't working. Could somebody clarify whether or not I'm just making a dumb newbie mistake?
You can call WithParams whenever you want in the query. That's what the Neo4jClient doco means about "at any point in the fluent query".
However, Neo4j only supports parameters in certain parts of the Cypher text. If the parameter would affect the query plan, it's not allowed.
In this case, you cannot use parameters for labels. You will need to actually construct the query dynamically if you want to do that.
Edit: Even if this was a supported place for parameters, you'd at least have to write {nodeLabel} in your Cypher instead of just nodeLabel.
I turned on node auto-indexing and it's indexing the properties I need. If I start up the Neo4j server and open the webadmin, I see that there is an index called node_auto_index as per this post. It works perfectly from the webadmin and I can run Cypher queries like this:
START n=node:node_auto_index('__type:user AND __username:admin') RETURN n
The query returns exactly what I expect. However, if I shut down the server and open the DB in embedded mode from a Scala application, this doesn't work. If I try to run the same Cypher query, I get an error that node_auto_index doesn't exist. I checked the GraphDatabaseService properties, and auto indexing is up and running on the right keys, but when getting a list of all of the index names, the list is always empty. And I can't use the AutoIndex API because it only indexes on one property, and I definitely need both.
So from this point, what would be the best way to ago about querying the auto-index with multiple properties from my Scala (Java) code?
EDIT: I noticed that the ReadableIndex interface (which is what the auto-index is) can take a query string. I can't find much documentation on it, so I'm going to try a few things, but is there any chance that could take a Cypher query? Or just the single-quoted string in my query above?
Turns out that the query function of the ReadableIndex actually takes a Lucene Query, which I now realize is what I had quoted above. So calling this code:
val nodes = db.index.getNodeAutoIndexer.getAutoIndex.query("__type:user AND __username:admin")
Gave me exactly what I wanted.