QuestDB + SwiftNIO

A QuestDB REST client designed to work with server-side Swift applications with Codable support.

Install (SPM)

Add the package to your dependencies in Package.swift:

dependencies: [
  .package(url: "https://github.com/swift-glide/questdb-nio.git", .from("0.1.0"))
]

Usage

Start by creating a client instance:

let client = QuestDBClient()

When no configuration is passed, the client will look for the QUESTDB_URL environment variable and use it if available. Otherwise, it will default to http://localhost:9000.

You can pass a configuration object as well as an NIO HTTP client during initialization:

let client = QuestDBClient(
  config: QuestDBConfig(url: "http://localhost:9000"),
  httpClient: HTTPClient(
    eventLoopGroupProvider: .createNew
  )
)

Once you have a client, you can call the execute instance method to execute your queries:

client.execute(
  options: ExecuteOptions(
    query: """
    CREATE TABLE readings(
        db_ts timestamp,
        device_ts timestamp,
        device_name symbol,
        reading int)
    timestamp(db_ts);
    """
  )
)

If you want the query to execute on a specific event loop, you can pass it as an argument as well:

client.execute(
  on: someEventLoop, 
  options: ...
)

This method returns an event loop future wrapping a Codable type.

If the return type can't be inferred from the call site, you can specify it as follows:

client.execute(
  on: someEventLoop, 
  options: ...,
  returning: SomeDecodableType.self
)

Many requests return a QuestOperationResponse object, so use it accordingly.

You can further customize your request using the ExecuteOptions type, including count, limit, nm, and timings. Please refer to the official QuestDB docs for more information.

Supported Endpoints

• /exec
• /imp
• /exp

Vapor + QuestDB

If you plan to use this package with a Vapor 4 app, here are some snippets to get you started. We first create a service type inside Application:

import Vapor
import QuestDB

extension Application {
  struct QuestDB {
    let app: Application

    struct Key: StorageKey {
      typealias Value = QuestDBClient
    }

    var client: QuestDBClient {
      get {
        guard let client = self.app.storage[Key.self] else {
          fatalError("QuestDBClient is not setup. Use application.quest.client to set it up.")
        }

        return client
      }

      nonmutating set {
        self.app.storage.set(Key.self, to: newValue) {
          try $0.syncShutdown()
        }
      }
    }
  }

  var quest: QuestDB {
    .init(app: self)
  }

  var questClient: QuestDBClient {
    quest.client
  }
}

Then we do the same with Request:

extension Request {
  struct QuestDB {
    var client: QuestDBClient {
      return request.application.quest.client
    }

    let request: Request
  }

  var quest: QuestDB { .init(request: self) }

  var questClient: QuestDBClient {
    quest.client
  }
}

When configuring your app instance:

let client = QuestDBClient(httpClient: app.http.client.shared)
app.quest.client = client

For operations that you do frequently, you can extend the client to keep things DRY:

extension QuestDBClient {
  func createTable(
    on eventLoop: EventLoop? = nil
  ) -> Future<QuestOperationResponse> {
    execute(
      on: eventLoop,
      options: .init(
        query: """
        ...
        """
      )
    )
  }

Project Status & Contributions

The package handles all the use cases that it was initially designed for. That being said, PRs are very welcome, especially if they tackle some of the following:

• Adding missing endpoints.
• Adding a test suite.

License

See LICENSE.