CODEWITHSUNDEEP
csvgraphneo4jmergecypher
jorzylicious
jorzylicious

Reputation: 101

Import a CSV file with null values in Neo4j

This is supposed to be a really easy task and yet I am struggling. To all the people who are expert in a graph-database and Neo4j I would really appreciate some help and make my life a bit easier. I can't seem to figure out this MERGE clause with NULL values in CSV files.

Example.csv file contains

Name,Lastname,Team,Room

AAAA,BBBB,CCCC,1111

DDDD,EEEE,FFFF,2222

GGGG,HHHH,,3333

IIII,JJJJ,KKKK,

LLLL,MMMM,CCCC,1111

NNNN,OOOO,,2222

When executing

LOAD CSV WITH HEADERS FROM 'file:///EXAMPLE.csv' AS row WITH row RETURN row

I can see some fields like Team and Room has null values. I would like to create nodes for Employees, Team and Room and here is the code I have written so far.

CREATE CONSTRAINT ON (t:Team) ASSERT t.name IS UNIQUE;

CREATE CONSTRAINT ON (r:Room) ASSERT r.name IS UNIQUE;

LOAD CSV WITH HEADERS FROM 'file:///EXAMPLE.csv' AS row WITH row WHERE row.Room <> '' AND row.Room IS NOT NULL AND row.Team <> '' AND row.Team IS NOT NULL

CREATE (m:Employee {name: toUpper(row.Lastname), firstname: toUpper(row.Name)})

MERGE (r:Room { name:row.Room})

MERGE (t.Team {name:row.Team})

CREATE (m)-[:WORKS_IN]->(r)

CREATE (m)-[:WORKS_WITH]->(t);

I guess you already guessed some entries with null values are cancelled and not taken. I want to keep the Employees within the database even it has no entries in department or team ie. no relationship exists if null.

I would really appreciate some help and many thanks in advance.

Upvotes: 2

Views: 3988

Answers (1)

Bruno Peres
Bruno Peres

Reputation: 16365

You can try using FOREACH and CASE WHEN to handle conditions. Something like this:

CREATE (m:Employee {name: toUpper(row.Lastname), firstname: toUpper(row.Name)})
FOREACH (n IN (CASE WHEN row.Room IS NULL THEN [] ELSE [1] END) |
    MERGE (r:Room { name:row.Room})
    CREATE (m)-[:WORKS_IN]->(r)
)
FOREACH (n IN (CASE WHEN row.Team IS NULL THEN [] ELSE [1] END) |
    MERGE (t:Team {name:row.Team})
    CREATE (m)-[:WORKS_WITH]->(t)
)

The FOREACH block will be executed only once when the related line is different of null.

Upvotes: 4

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