Using Alecrim Core Data with Swift 3 - swift

Question

I'm having trouble with Alecrim Core Data in Xcode 8 Beta. The DataContext and DataContextOptions seem to be missing from the Swift_3 branch. Grasping at straws, I just updated the files from the master branch to Swift3 syntax hoping the functionality hadn't changed too much. But when it tries to read data I get an error message "Cannot fetch without an NSManagedObjectContext in scope".
I've done as much triage as I can think of. Breakpoints set at the spot that creates an NSManagedObjectContext and I can see it. The place that creates the fetchRequest has been updated with the new NSFetchReqeust syntax (although I see no sign of a MOC there).
Here's my link into the Alecrim lib DataContext:
let dataContext = DataContext()
extension DataContext
{
public var collections: Table<CoreDataCollection> { return Table<CoreDataCollection>(context: self) }
public var expressions: Table<CoreDataExpression> { return Table<CoreDataExpression>(context: self) }
public var fileAssets: Table<CoreDataFileAsset> { return Table<CoreDataFileAsset>(context: self) }
public var purchases: Table<CoreDataPurchase> { return Table<CoreDataPurchase>(context: self) }
public var reeConfigs: Table<CoreDataReeConfig> { return Table<CoreDataReeConfig>(context: self) }
public var stickers: Table<CoreDataSticker> { return Table<CoreDataSticker>(context: self) }
}
And the part that attempts to get data:
for item in dataContext.reeConfigs {
let reeConfigVO = ReeConfigVO()
reeConfigVO.initFromCoreData(item)
items.append(reeConfigVO)
}
I'm not sure if this will be helpful but the part of Alecrim that's tossing the error:
// MARK: - GenericQueryable
extension TableProtocol {
public final func execute() -> [Self.Element] {
do {
return try self.toFetchRequest().execute() as [Self.Element]
}
catch let error {
AlecrimCoreDataError.handleError(error)
}
}
}
// MARK: - CoreDataQueryable
extension TableProtocol {
public final func toFetchRequest<ResultType: NSFetchRequestResult>() -> NSFetchRequest<ResultType> {
let fetchRequest = NSFetchRequest<ResultType>()
fetchRequest.entity = self.entityDescription
fetchRequest.fetchOffset = self.offset
fetchRequest.fetchLimit = self.limit
fetchRequest.fetchBatchSize = (self.limit > 0 && self.batchSize > self.limit ? 0 : self.batchSize)
fetchRequest.predicate = self.predicate
fetchRequest.sortDescriptors = self.sortDescriptors
return fetchRequest
}
}
Does anyone have experience with Alecrim in Swift 3 that can help figure out what's going wrong?
Thanks,
Mike

Answer 1

I found the answer I was looking for. I'm not sure this is what Alecrim wants to be done because, as I mentioned, the swift_3 branch doesn't even contain DataContext or DataContextOptions. However... if you have brought those files in from the main branch and updated them to swift 3 as I have and you have problems with the error "Cannot fetch without an MSManagedObjectContext in scope" here's how to fix it in the "TableProtocol.swift" file:
extension TableProtocol {
public final func execute() -> [Self.Element] {
do {
return try self.context.fetch(self.toFetchRequest()) as! [Self.Element]
//return try self.toFetchRequest().execute() as [Self.Element]
}
catch let error {
AlecrimCoreDataError.handleError(error)
}
}
}
self.context is the NSManagedObjectContext (or a derived type i.e. our DataContext) that is needed for this to work. The as! [Self.Element] is crucial because Swift uses it to infer the RestultType in the function that builds the NSFetchRequest
Hope this helps.