Theo, the Neo4j Swift driver, works well with Vapor 4.
For future reference: This post was written with Theo 5.2.0, Vapor 4.15.2 and Swift 5.2.4

Let's have a look at how to use it together, starting with the crudest example:



In the code above, we start with the theoClient function that in it's completion block provides a Bolt client. Bolt is the binary protocol used to talk to a Neo4j instance. I've configured it to connect to the instance on my machine at port 7687, the default Bolt port. I provide a username and password, and ask it to connect via SSL, a configuration you may know from the Neo4j browser as bolt+s.

For this example, I've written a router with only one endpoint and implemented it straight away. When a request is made, we make a promise to Vapor that we'll return a string. Then we ask for a Theo client, and define a new node we want to insert. The node contains a single label: "New", and a single property "createdTime", with the current time as a TimeInterval (a.k.a. Double).

We ask the client to create it, and if it is successful, we fulfil our promise saying "Newly created node!". If, however, there is a problem, we complete with a failure and report the error.