Singleton neo4j

[okjodom]

A singleton neo4jService that encapsulates driver. Layers don't need to have a knowledge of underlying neo4j driver. Composition proposed here allows us to smoothly swap out drivers in future #65, and remove driver instantiation on critical boot path #78.
Additionally, this PR formalizes a result API on neo4jService endpoints. Success from service calls return as { status: 200, result: someResult } while failures return { status: 500, error: errorWithStack }

Next: This pattern opens up an opportunity for better error ux, most immediately, a path for solving #77 [ don't rerender if we hit error on create/update new layer ]

PS: Builds on top of changes in PR #75

[okjodom]

cc @wagnerjt for reviews on service changes

[okjodom]

Not ready until I add tests for the driver... :)

[okjodom]

Not ready until I add tests for the driver... :)

done. @stellasia, @wagnerjt I'd love your reviews on pr

[okjodom]

A singleton neo4jService that encapsulates driver. Layers don't need to have a knowledge of underlying neo4j driver. Composition proposed here allows us to smoothly swap out drivers in future #65, and remove driver instantiation on critical boot path #78.
Additionally, this PR formalizes a result API on neo4jService endpoints. Success from service calls return as { status: 200, result: someResult } while failures return { status: 500, error: errorWithStack }

Next: This pattern opens up an opportunity for better error ux, most immediately, a path for solving #77 [ don't rerender if we hit error on create/update new layer ]

PS: Builds on top of changes in PR #75

@stellasia, let's review and close this PR when possible.

[stellasia]

Sure, will do during the coming week!

[stellasia]

I found a couple of other bugs when reviewing but not related to this PR. So looks good to me when the issue with records is fixed (see comment in code)

[stellasia]

Thank you very much for this @JoDoM , merging 💯