I am writing an API using the server side swift framework Vapor. My model is very simple. I have a Workout table, which has a to many relationship to the Circuit table, which has a to many relationship with the Exercise table. When the api consumer creates a workout, the json contains all circuits and exercises in the workout. Here is an example:
{
...
circuits: [{
...,
exercises: [{
"title": ...
}, {
"title": ...
}]
}, {
...,
exercises: [{
"title": ...
}, {
"title": ...
}]
}]
}
The problem I am running into is duplicate exercises being created, when the user has the same exercise in multiple circuits. I query the db before creating a new exercise, but it seems like the saves are all happening asynchronously, which prevents me from detecting an existing exercise with the same id/title in the db before saving a new one. Here is my code:
private func saveExercise(on conn: DatabaseConnectable, with content: WorkoutCreateExerciseContent, for authUser: User) throws -> Future<Exercise> {
if let exerciseId: UUID = content.id {
return Exercise.find(exerciseId, on: conn)
.unwrap(or: Abort(.badRequest, reason: "No exercise for id: \(exerciseId.uuidString)"))
} else if let title: String = content.title, let isPublicallyVisible: Bool = content.isPublicallyVisible {
return Exercise.query(on: conn).filter(\.title == title).filter(\.directions == content.directions).first().flatMap({ (possibleMatchingExercise: Exercise?) -> Future<Exercise> in
if let matchingExercise: Exercise = possibleMatchingExercise {
return conn.future(matchingExercise)
} else {
print("xxx Found no match for \(title)")
let newExercise: Exercise = Exercise(
title: title,
directions: content.directions,
isPublicallyVisible: isPublicallyVisible
)
newExercise.userId = authUser.id
return newExercise.save(on: conn)
}
})
} else {
throw Abort(.badRequest, reason: """
Bad data for exercise. Expecting either of the following:
{
/"id/": /"some id/"
}
or
{
/"title/": /"some title/"
/"directions/": /"(optional)/",
/"isPublicallyVisible/": false
}
id takes priority over other properties.
""")
}
}
private func saveCircuit(on conn: DatabaseConnectable, with content: CircuitCreateContent, order: Int, workoutId: UUID, authUser: User) throws -> Future<Circuit> {
return try content.exercises.map({ (exerciseContent: WorkoutCreateExerciseContent) throws -> Future<Exercise> in
let createdExercise: Future<Exercise> = try self.saveExercise(
on: conn,
with: exerciseContent,
for: authUser
)
return createdExercise
})
.flatten(on: conn)
.flatMap({ (exercises: [Exercise]) -> Future<Circuit> in
let circuit: Circuit = Circuit(
workoutId: workoutId,
order: order,
exerciseDuration: content.exerciseDuration,
restDuration: content.restDuration,
exerciseIDs: exercises.compactMap({ $0.id })
)
return circuit.save(on: conn)
})
}
func saveWorkout(_ conn: DatabaseConnectable, _ authentiatedUser: User, _ content: WorkoutCreateContent) throws -> Future<Workout> {
let workout: Workout = content.makeWorkout()
workout.userId = authentiatedUser.id
// First save the exercises
let createdWorkout: Future<Workout> = workout.save(on: conn).flatMap({ (savedWorkout: Workout) -> Future<Workout> in
let createdCircuits: Future<[Circuit]> = try content.circuits.enumerated().map({ (order: Int, circuitContent: CircuitCreateContent) throws -> Future<Circuit> in
let createdCircuit: Future<Circuit> = try self.saveCircuit(
on: conn, with: circuitContent,
order: order,
workoutId: savedWorkout.id!,
authUser: authentiatedUser
)
return createdCircuit
})
.flatten(on: conn)
return createdCircuits.then({ _ -> Future<Workout> in
return conn.future(savedWorkout)
})
})
return createdWorkout
}
Does anyone see what I'm missing here? Is there a way to wait for a Future to fulfill before starting a new Future? I am new to Vapor, so I'm not that familiar with Vapor's fluent api.
