Adding an attribute to a Relationship - neo4j

I am trying to load a CSV file using LOAD FROM CSV and build a relationship. I have a crossover table that I am using to support a many to many relationship. For my example I will use two (2) primary nodes, Car and Driver.
A Car can be driven by one or more Drivers and a Driver can drive one or more Cars.
My cross over table looks like this
CarID (int)
DriverID (int)
Here is my code to successfully load it into Neo4j
LOAD CSV WITH HEADERS FROM 'FILE:///CarToDriverXFER.csv' AS row FIELDTERMINATOR ','
MATCH (c:Cars {carID:row.carID})
MATCH (d:Drivers {driverID:row.driverID})
MERGE (c)-[:DRIVES]->(d)
I want to add an attribute into this relationship. Now the table looks like this:
CarID (int)
DriverID (int)
Rating (int)
I am not sure how to do this. I know how to do this if the object is a node but I am not getting the syntax correct with regards to build a relationship. Here is my attempt at a solution but I am getting an error.
LOAD CSV WITH HEADERS FROM 'FILE:///CarToDriverXFER.csv' AS row FIELDTERMINATOR ','
MATCH (c:Cars {carID:row.carID})
MATCH (d:Drivers {driverID:row.driverID})
CREATE ({Rating:row.Rating})
MERGE (c)-[:DRIVES]->(d)
The above script loaded the relationships but the attribute "Rating" is not listed on the attribute.
Can anyone offer help?

You can add the attribute to the relationship the same way you add attributes to nodes, that is:
LOAD CSV WITH HEADERS FROM 'FILE:///CarToDriverXFER.csv' AS row FIELDTERMINATOR ','
MATCH (c:Cars {carID:row.carID})
MATCH (d:Drivers {driverID:row.driverID})
// adding 'Rating' attribute to ':Drives' relationship between 'c' and 'd'
MERGE (c)-[:DRIVES {Rating:row.Rating}]->(d)

Related

My match/merge process is not creating relationships in the Neo4J database

I am very new to Neo4j/cypher/graph databases, and have been trying to follow the Neo4j tutorial to import data I have in a csv and create relationships.
The following code does what I want in terms of reading in the data, creating nodes, and setting properties.
/* Importing data on seller-buyer relationshsips */
USING PERIODIC COMMIT 1000
LOAD CSV WITH HEADERS FROM 'file:///customer_rel_table.tsv' AS row
FIELDTERMINATOR '\t'
MERGE (seller:Seller {sellerID: row.seller})
ON CREATE SET seller += {name: row.seller_name,
root_eid: row.vendor_eid,
city: row.city}
MERGE (buyer:Buyer {buyerID: row.buyer})
ON CREATE SET buyer += {name: row.buyer_name};
/* Creating indices for the properties I might want to match on */
CREATE INDEX seller_id FOR (s:Seller) on (s.seller_name);
CREATE INDEX buyer_id FOR (b:Buyer) on (b.buyer_name);
/* Creating constraints to guarantee buyer-seller pairs are not duplicated */
CREATE CONSTRAINT sellerID ON (s:Seller) ASSERT s.sellerID IS UNIQUE;
CREATE CONSTRAINT buyerID on (b:Buyer) ASSERT b.buyerID IS UNIQUE;
Now I have the nodes (sellers and buyers) that I want, and I would like to link buyers and sellers. The code I have tried for this is:
USING PERIODIC COMMIT 1000
LOAD CSV WITH HEADERS FROM 'file:///customer_rel_table.tsv' AS row
MATCH (s:Seller {sellerID: row.seller})
MATCH (b:Buyer {buyerID: row.buyer})
MERGE (s)-[st:SOLD_TO]->(b)
The query runs, but I don't get any relationships:
Query executed in 294ms. Query type: WRITE_ONLY.
No results.
Since I'm not asking it to RETURN anything, I think the "No results" comment is correct, but when I look at metadata for the DB, no relationships appear. Also, my data has ~220K rows, so 294ms seems fast.
EDIT: At #cybersam's prompting, I tried this query:
MATCH p=(:Seller)-[:SOLD_TO]->(:Buyer) RETURN p, which gives No results.
For clarity, there are two fields in my data that are the heart of the relationship:
seller and buyer, where the seller sells stuff to the buyer. The seller identifiers are repeated, but for each seller there are unique seller-buyer pairs.
What do I need to fix in my code to get relationships between the sellers and buyers? Thank you!
Your second query's LOAD CSV clause does not specify FIELDTERMINATOR '\t'. The default terminator is a comma (','). That is probably why it fails to MATCH anything.
Try adding FIELDTERMINATOR '\t' at the end of that clause.

How to create relationship between two existing nodes by using node id?

I am trying to create a relationship between two existing nodes. I am reading the node ID's from a CSV and creating the relationship with the following query:
LOAD CSV WITH HEADERS FROM "file:///8245.csv" AS f
MATCH (Ev:Event) where id(Ev) =f.first
MATCH (Ev_sec:Event) where id(Ev_sec) = f.second
WITH Ev, Ev_sec
MERGE (Ev) - [:DF_mat] - > (Ev_sec)
However, it is not changing anything the database. How can I solve this problem?
Thanks!
I solved the problem. So, I again queried for the ID(node) and this time I exported them as a string (by using toString(ID(node)) ). Then while loading to the database, I converted them to Integer. The query is as follows:
LOAD CSV WITH HEADERS FROM "file:///8245_new.csv" AS csvLine
match (ev:Event) where id(ev)=toInteger(csvLine.first)
match (ev_sec:Event) where id(ev_sec)=toInteger(csvLine.second)
merge (ev)-[:DF_mat]-> (ev_sec)

Node and relationship creation in Neo4j

I have a data set, which looks like this
Now, as one can see that a single person has multiple skillid, along with this data, i also have a skill_ref table, which has 2 columns(skillid and skillname) so from the image above, i can look and say that last person has multiple skills, Now, i want this data to be put in Neo4j, with person and skillname as node, and a relationship of has_skill. But i dont know how to handle the multiple instances, if i split the skillid , then i will have multiple instances of person name, but this is not what i want, i want something like this
in the graph,the center node is the name of the person and the others have skill name, with the arrows pointing a relation has_skill.
I am new to neo4j as well as cypher, any help guys will be highly appreciated.
USING PERIODIC COMMIT
LOAD CSV WITH HEADERS FROM "file:///people_data.csv" AS line
CREATE (p:Person{id:line.people_uid})
WITH line, p
SET p.firstName = line.first_name,p.lastname=line.last_name
WITH line,split(line.skillid,' ') as skill_ids
UNWIND skill_ids as skill_Id
MERGE (skill:Skill{id:skill_Id})
LOAD CSV WITH HEADERS FROM "file:///skills_ref.csv" AS line
WITH line
MERGE(skill:line.skillid{name:line.skillname})
CREATE (p)-[:HAS_SKILL]->(skill)
You've got the right idea.
The general approach is to first MERGE (or CREATE) the :Person node, then split() the skillid into a list of skill ids, UNWIND the skill id list into rows, then MERGE the skill for the given id (and make sure you have an index or unique constraint on :Skill(id)), then MERGE (or CREATE) the relationship between the :Person node and the :Skill.
Here's an example, loading from a CSV file:
USING PERIODIC COMMIT
LOAD CSV WITH HEADERS FROM "file:///your.file.url" AS line
CREATE (p:Person{id:line.people_uid})
WITH line, p
SET p.firstName = line.f_name ... <same for the rest of the properties>
UNWIND split(line.skillid, ' ') as skillId
MERGE (skill:Skill{id:skillId})
CREATE (p)-[:HAS_SKILL]->(skill)
EDIT
Regarding the revised query you're attempting, it's actually better to use separate queries for each csv load, using the first to create the nodes and merge the relationships, and the second just to match/merge to skills and add the skill name:
USING PERIODIC COMMIT
LOAD CSV WITH HEADERS FROM "file:///people_data.csv" AS line
CREATE (p:Person{id:line.people_uid})
SET p.firstName = line.first_name, p.lastname=line.last_name
WITH line, split(line.skillid, ' ') as skill_ids
UNWIND skill_ids as skill_Id
MERGE (skill:Skill{id:skill_Id})
CREATE (p)-[:HAS_SKILL]->(skill)
Then your next query:
LOAD CSV WITH HEADERS FROM "file:///skills_ref.csv" AS line
MERGE (skill:Skill{id:line.skillid})
SET skill.name = line.skillname
Remember that you should have an a unique constraint created on :Skill(id) and :Person(id) first.

Performance: Creating a relationship in neo4j based on property ID

For test purposes i imported data from another datasource into neo4j.
I imported the data only as nodes. Now i want to add the edges based on the imported ID. Every node has 2 fields
id: contains the identification as String
from: contains all connections as a String[]
For performance improvements i also created an index for the propertiy "id" and an index for the property "from"
First i created both properties as String (the from list as comma separated String).
This works, but is really slow:
MATCH (e:Test1),(r:Test2)
WHERE r.from CONTAINS e._id
MERGE (e)-[:HAS]->(r)
is there a better way?
PS: i tried also to store the from field as String[]. than i used the following query
MATCH (e:Test1),(r:Test2)
WHERE e._id IN r.from
MERGE (e)-[:HAS]->(r)
-> Performance is the same
The problem is that you take a combination of all components - the Cartesian product. In both cases. More would be better to split the string by comma to identifiers. For example:
MATCH (T2:Test2)
UNWIND split(T2.from, ",") as id
MATCH (T1:Test1) WHERE T1._id = id
MERGE (T1)-[:HAS]->(T2)
Or, if you keep the identifiers in the array:
MATCH (T2:Test2)
UNWIND T2.from as id
MATCH (T1:Test1) WHERE T1._id = id
MERGE (T1)-[:HAS]->(T2)
And, of course, do not forget about the index.
Actually, at import time, you should be creating the :HAS relationships instead of creating the from property (which forces you to make a wasteful additional query to create the relationships, and leaves you with redundant from properties that you would probably want to delete).
For example, if you are using LOAD CSV to import, and your import file has test2Id and from columns (a string and a string collection, respectively), this import query should create all the nodes and relationships:
LOAD CSV WITH HEADERS FROM "file:///input.csv" AS row
MERGE (t2:Test2 {id: row.test2Id})
WITH row, t2
UNWIND row.from AS t1Id
MERGE (t1:Test1 {id: t1Id})
MERGE (t1)-[:HAS]->(t2);
For better performance, you would want indexes on both :Test1(id) and :Test2(id).

neo4j Optimize a relationsship check (query)

after importing data via CSV LOAD I want to connect the imported nodes to customer nodes that are already in the DB. The idea was to look up all imported nodes with the Label TICKET and run through the result set and create the relationship.
Here is the code I come up with first approach:
# Find nodes without relationship for label Ticket
MATCH (t:Ticket), (c:Customer)
WHERE NOT (t)--(c)
RETURN t.number as ticket_number, t.type as ticket_type,t.sid as ticket_sid
# Run through the resultset and execute for each found node
MATCH (t:Ticket { number: "xxx" }), (c:Customer {code: "xxx"})
MERGE (t)-[:IS_TICKET_OF]->(c);
There is an index
ON :Ticket (number)
ON :Customer(code)
This way to handle it is very slow and it took minutes to run through the CSV file. I hope there is a way to optimize the query or maybe to find a way to create the missing relationship easier as first to look them all up and then run through a loop.
The CSV Load is :
LOAD CSV FROM "file:c:..." AS csvLine
MERGE (t:Ticket { number: csvLine[0]})
Maybe its also fine to create the relation already in the CSV import - maybe something like
MATCH (c:Customer {code:"xxx"})
MERGE (t) - [:IS_TICKET_OF]-> (c)
But I would need to figure out in the query how to extract the code from a field as I have something like "aaa/vvv/bbb/1234" in the CSV import and would need only aaa for the match above as this is stored in the customer node as ID.
Any hint is very appreciated.
Thanks!
Does this query work for you?
It stores the aaa part of the input string in num, makes sure the ticket with that number exists, and then makes sure a relationship exists to the matching customer (if there is such a customer).
LOAD CSV FROM "file:c:..." AS csvLine
WITH SPLIT(csvLine[0], '/')[0] AS num
MERGE (t:Ticket {number: num})
WITH num, t
OPTIONAL MATCH (c:Customer {code: num})
MERGE (t)-[:IS_TICKET_OF]->(c);

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