startGraph: Prepare connection to neo4j database

Description

Prepare connection to neo4j database

Usage

startGraph(
  url,
  database = NA,
  username = NA,
  password = NA,
  importPath = NA,
  .opts = list(),
  check = TRUE,
  api = c("auto", "tx", "v2"),
  cypher_version = c("auto", "")
)

Value

A connection to the graph DB: a list with the url and necessary headers

Arguments

url: the DB url
database: the name of the database. If NA (default) it will use "data" with versions 3.. of Neo4j and "neo4j" with versions 4..
username: the neo4j user name (default: NA; works only if authentication has been disabled in neo4j by setting NEO4J.AUTH=none)
password: the neo4j user password (default: NA; works only if authentication has been disabled in neo4j by setting NEO4J.AUTH=none)
importPath: path to the import directory (default: NA => no import directory). Import only works with local neo4j instance.
.opts: a named list identifying the curl options for the handle (see httr2::req_options() and curl option names for a complete list of available options; for example: .opts = list(ssl_verifypeer = 0)). Moreover, this parameter can be used to pass additional headers to the graph requests as "extendedHeaders": it is useful, for example, for OAuth access delegation (see details).
check: check the connection before returning it (default: TRUE). Set to false when connection to the "system" database
api: the HTTP API to use: "tx" for the legacy Transactional Cypher HTTP API (default for self-managed instances), "v2" for the Neo4j Query API v2 (required for Aura, available on self-managed Neo4j >= 5.19), or "auto" (default) to detect automatically — Aura URLs (*.databases.neo4j.io) select "v2", all others select "tx".
cypher_version: The version of the cypher language used by the database. Should be "" for neo4j version <= 5.

Details

The "ssl.verifypeer" logical option available in the RCurl package used in former versions of neo2R (<= 2.2.0) is not recognized by httr2::req_options(). However, for backward compatibility, if it is used, it is translated into the "ssl_verifypeer" integer curl option with a warning message.

Headers in .opts$extendedHeaders are added to, or overwrite, the default Neo4j headers. If there is a .opts$extendedHeaders[["Authorization"]] value, the default Neo4j "Authorization" header (user credentials) is provided automaticaly as "X-Authorization". This mechanism is used for OAuth access delegation.