Querying Neo4J

The function neo4j_query() can be used to send a query to a local or remote Neo4J server. This function uses cypher-shell to send the query to Neo4J, and so the cypher-shell executable needs to be installed and available locally. See the README file for further information on configuration of the cypher-shell executable.

neo4j_query() takes the following arguments:

• con should be a list containing three elements: address, which should be the bolt address of the Neo4J server, and uid and pwd as login credentials
• qry should be a character string representing the query to be sent to Neo4J
• shell_path should be the full path to the cypher-shell executable. The default value assumes that cypher-shell is already in the system path. Use path.expand() if necessary.
  
• database specifies the database to be queried if not the default database. (For multitenancy Neo4J installations).
• encryption is the encryption option passed to cypher-shell. This may be required as explicitly 'true' or 'false' for older installations.

Example, assuming a local Neo4J instance running the movies graph:

library(neo4jshell)

neo4j_local <- list(address = "bolt://localhost", uid = "neo4j", pwd = "password")
CQL <- 'MATCH (p1:Person {name: "Kevin Bacon"})-[:ACTED_IN]->(m:Movie)<-[:DIRECTED]-(p2:Person)
        RETURN p2.name AS Name, m.title AS Title'
cypher_path <- path.expand("~/neo4j-community-4.0.4/bin/cypher-shell")
neo4j_query(con = neo4j_local, qry = CQL, shell_path = cypher_path)

This query should return this dataframe:

#>         Name          Title
#> 1 Ron Howard    Frost/Nixon
#> 2 Rob Reiner A Few Good Men
#> 3 Ron Howard      Apollo 13

neo4j_query() accepts multiple query statements separated by ;. The function returns one of the following:

• A dataframe of results if the query is a read query. If there were multiple statements, only the results of the final statement will display.
• A message indicating successful execution if the query is a write query.
• An error message if an error occurred. If there were multiple statements, the response for all statements will be displayed.