Nodes

In this lesson, you will learn how to use the MERGE clause to create nodes using data from a CSV file.

Load the CSV file

You will load a CSV file of "person" data into Person nodes in Neo4j. The CSV file contains the following fields:

person_tmdbId
bio
born
bornIn
died
person_imdb
Id
name
person_poster
person_url

Follow these instructions to open the file and inspect the contents:

Download the persons.csv file
Open the file using a text editor to look at the contents.

You should see that the file contains headers, and the field delimiter is a comma (,).

Run the following Cypher statement to load the CSV file and return the contents:

cypher

LOAD CSV WITH HEADERS
FROM 'https://data.neo4j.com/importing-cypher/persons.csv' AS row
RETURN row

The next step is to use the data in the CSV file to create Person nodes.

Before running it, review the following Cypher statement:

cypher

LOAD CSV WITH HEADERS
FROM 'https://data.neo4j.com/importing-cypher/persons.csv' AS row
MERGE (p:Person {tmdbId: toInteger(row.person_tmdbId)})
SET
p.imdbId = toInteger(row.person_imdbId),
p.bornIn = row.bornIn,
p.name = row.name,
p.bio = row.bio,
p.poster = row.poster,
p.url = row.url,
p.born = row.born,
p.died = row.died

Try to answer the following questions:

Where does the CSV data come from?
What does the MERGE clause do?
What variable holds the data from the CSV file?
Where are the properties set?
Why is the toInteger function used?

Review the answers

The LOAD CSV clause loads the CSV file from the specified URL.
The MERGE clause creates a new Person if one does not already exist with the same tmdbId value.
The row variable holds the data from the CSV file.
The SET clause sets the properties of the Person node to the values of the corresponding fields in the CSV file.
The toInteger function converts the person_tmdbId and person_imdbId values from strings to integers.

Create Person nodes

Run the Cypher statement to create the Person nodes:

cypher

LOAD CSV WITH HEADERS
FROM 'https://data.neo4j.com/importing-cypher/persons.csv' AS row
MERGE (p:Person {tmdbId: toInteger(row.person_tmdbId)})
SET
p.imdbId = toInteger(row.person_imdbId),
p.bornIn = row.bornIn,
p.name = row.name,
p.bio = row.bio,
p.poster = row.poster,
p.url = row.url,
p.born = row.born,
p.died = row.died

The import should create 444 Person nodes.

Confirm the data is in the graph by returning the first 25 Person nodes:
cypher
```
MATCH (p:Person) RETURN p LIMIT 25
```
Check the results. Do the nodes have the correct properties?

Check Your Understanding

Creating nodes

Select the correct Cypher statement to create a node from data in a CSV file.

cypher

LOAD CSV WITH HEADERS 'file:///games.csv' AS record
/*select:MERGE (g:Game {title: row.title})*/

❏ MERGE (g:Game {title: row.title})
❏ MERGE (g:Game {title: g.title})
✓ MERGE (g:Game {title: record.title})

Hint

You get data from the CSV by using the file’s alias.

Solution

The alias of the CSV file is record. You would use record when setting property values.

cypher

LOAD CSV WITH HEADERS FROM 'file:///games.csv' AS record
MERGE (g:Game {title: record.title})

Summary

In this lesson, you reviewed a Cypher statement that loads a CSV file and creates nodes from the data in the file.

Importing CSV data into Neo4j

Importing Data

Creating Nodes, Properties, and Relationships

Data Types, Lists, and Labels

Importing data considerations

Nodes

Load the CSV file

Create Person nodes

Check Your Understanding

Creating nodes

Summary

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