Is is possible to use Vapor 3 Postgres Fluent in a standalone script?

问题

I am experimenting with a standalone script that will query a Postgres database using Vapor and Fluent. In a normal Vapor API application this is simply done by:

router.get("products") { request in
    return Product.query(on: request).all()
}

However, in a standalone script, since there is no "request", I get stuck on what to replace the "request" or DatabaseConnectable with. Here's where I get stuck on:

import Fluent
import FluentPostgreSQL

let databaseConfig = PostgreSQLDatabaseConfig(hostname: "localhost",
                                              username: "test",
                                              database: "test",
                                              password: nil)

let database = PostgreSQLDatabase(config: databaseConfig)

let foo = Product.query(on: <??WhatDoIPutHere??>)

I tried creating an object that conforms to DatabaseConnectable, but couldn't figure out how to correctly get that object to conform.

回答1:

You will need to create an event loop group to be able to make database requests. SwiftNIO's MultiThreadedEventLoopGroup is good for this:

let worker = MultiThreadedEventLoopGroup(numberOfThreads: 2)

You can change the number of threads used as you need.

Now you can create a connection to the database with that worker:

let conn = try database.newConnection(on: worker)

The connection is in a future, so you can map it and pass the connection in your query:

conn.flatMap { connection in
    return Product.query(on: connection)...
}

Make sure you shutdown your worker when you are done with it using shutdownGracefully(queue:_:)

回答2:

The above is very good, but just clarify how simple it is, when you get it, I have made a small test example for this. Hope it helps you.

final class StandAloneTest : XCTestCase{
    var expectation : XCTestExpectation?
    func testDbConnection() -> Void {
        expectation = XCTestExpectation(description: "Wating")
        let databaseConfig = PostgreSQLDatabaseConfig(hostname: "your.hostname.here",
                                                      username: "username",
                                                      database: "databasename",
                                                      password: "topsecretpassword")
        let database = PostgreSQLDatabase(config: databaseConfig)
        let worker = MultiThreadedEventLoopGroup(numberOfThreads: 2)
        let conn = database.newConnection(on: worker)

        let sc = SomeClass( a:1, b:2, c:3  ) //etc

        //get all the tupples for this Class type in the base
        let futureTest = conn.flatMap { connection in
              return SomeClass.query(on: connection).all()
        }
        //or save a new tupple by uncommenting the below
        //let futureTest = conn.flatMap { connection in
        //    return someClassInstantiated.save(on: connection)
        //}

        //lets just wait for the future to test it 
        //(PS: this blocks the thread and should not be used in production)
        do{
            let test = try futureTest.wait()
            expectation?.fulfill()
            worker.syncShutdownGracefully()
            print( test )
        }catch{
            expectation?.fulfill()
            print(error)
        }
    }
}

//Declare the class you want to test here using the Fluent stuff in some extension

来源：https://stackoverflow.com/questions/53786970/is-is-possible-to-use-vapor-3-postgres-fluent-in-a-standalone-script