Revert

CoreDataRepository/Package.resolved

@@ -0,0 +1,16 @@
+{
+  "object": {
+    "pins": [
+      {
+        "package": "CombineExt",
+        "repositoryURL": "https://github.com/CombineCommunity/CombineExt.git",
+        "state": {
+          "branch": null,
+          "revision": "d7b896fa9ca8b47fa7bcde6b43ef9b70bf8c1f56",
+          "version": "1.8.1"
+        }
+      }
+    ]
+  },
+  "version": 1
+}

CoreDataRepository/Package.swift

@@ -0,0 +1,33 @@
+// swift-tools-version:5.5
+// The swift-tools-version declares the minimum version of Swift required to build this package.
+
+import PackageDescription
+
+let package = Package(
+    name: "CoreDataRepository",
+    defaultLocalization: "en",
+    platforms: [
+        .iOS(.v15),
+        .macOS(.v12),
+        .tvOS(.v15),
+        .watchOS(.v8),
+    ],
+    products: [
+        .library(
+            name: "CoreDataRepository",
+            targets: ["CoreDataRepository"]
+        ),
+    ],
+    dependencies: [
+        .package(url: "https://github.com/CombineCommunity/CombineExt.git", .upToNextMajor(from: "1.5.1"))
+    ],
+    targets: [
+        .target(
+            name: "CoreDataRepository",
+            dependencies: [
+                .product(name: "CombineExt", package: "CombineExt"),
+            ],
+            path: "./Sources"
+        )
+    ]
+)

CoreDataRepository/Sources/CoreDataRepository/CoreDataRepository+Aggregate.swift

@@ -0,0 +1,251 @@
+// CoreDataRepository+Aggregate.swift
+// CoreDataRepository
+//
+//
+// MIT License
+//
+// Copyright © 2023 Andrew Roan
+
+import Combine
+import CoreData
+
+extension CoreDataRepository {
+    // MARK: Types
+
+    /// The aggregate function to be calculated
+    public enum AggregateFunction: String {
+        case count
+        case sum
+        case average
+        case min
+        case max
+    }
+
+    // MARK: Private Functions
+
+    private func request(
+        function: AggregateFunction,
+        predicate: NSPredicate,
+        entityDesc: NSEntityDescription,
+        attributeDesc: NSAttributeDescription,
+        groupBy: NSAttributeDescription? = nil
+    ) -> NSFetchRequest<NSDictionary> {
+        let expDesc = NSExpressionDescription.aggregate(function: function, attributeDesc: attributeDesc)
+        let request = NSFetchRequest<NSDictionary>(entityName: entityDesc.managedObjectClassName)
+        request.predicate = predicate
+        request.entity = entityDesc
+        request.returnsObjectsAsFaults = false
+        request.resultType = .dictionaryResultType
+        if function == .count {
+            request.propertiesToFetch = [attributeDesc.name, expDesc]
+        } else {
+            request.propertiesToFetch = [expDesc]
+        }
+
+        if let groupBy = groupBy {
+            request.propertiesToGroupBy = [groupBy.name]
+        }
+        request.sortDescriptors = [NSSortDescriptor(key: attributeDesc.name, ascending: false)]
+        return request
+    }
+
+    /// Calculates aggregate values
+    /// - Parameters
+    ///     - function: Function
+    ///     - predicate: NSPredicate
+    ///     - entityDesc: NSEntityDescription
+    ///     - attributeDesc: NSAttributeDescription
+    ///     - groupBy: NSAttributeDescription? = nil
+    /// - Returns
+    ///     - `[[String: Value]]`
+    ///
+    private static func aggregate<Value: Numeric>(
+        context: NSManagedObjectContext,
+        request: NSFetchRequest<NSDictionary>
+    ) throws -> [[String: Value]] {
+        let result = try context.fetch(request)
+        return result as? [[String: Value]] ?? []
+    }
+
+    private static func send<Value>(
+        context: NSManagedObjectContext,
+        request: NSFetchRequest<NSDictionary>
+    ) async -> Result<[[String: Value]], CoreDataRepositoryError> where Value: Numeric {
+        await context.performInScratchPad { scratchPad in
+            do {
+                let result: [[String: Value]] = try Self.aggregate(context: scratchPad, request: request)
+                return result
+            } catch {
+                throw CoreDataRepositoryError.coreData(error as NSError)
+            }
+        }
+    }
+
+    // MARK: Public Functions
+
+    /// Calculate the count for a fetchRequest
+    /// - Parameters:
+    ///     - predicate: NSPredicate
+    ///     - entityDesc: NSEntityDescription
+    /// - Returns
+    ///     - Result<[[String: Value]], CoreDataRepositoryError>
+    ///
+    public func count<Value: Numeric>(
+        predicate: NSPredicate,
+        entityDesc: NSEntityDescription
+    ) async -> Result<[[String: Value]], CoreDataRepositoryError> {
+        let _request = NSFetchRequest<NSDictionary>(entityName: entityDesc.name ?? "")
+        _request.predicate = predicate
+        _request
+            .sortDescriptors =
+            [NSSortDescriptor(key: entityDesc.attributesByName.values.first!.name, ascending: true)]
+        return await context.performInScratchPad { scratchPad in
+            do {
+                let count = try scratchPad.count(for: _request)
+                return [["countOf\(entityDesc.name ?? "")": Value(exactly: count) ?? Value.zero]]
+            } catch {
+                throw CoreDataRepositoryError.coreData(error as NSError)
+            }
+        }
+    }
+
+    /// Calculate the sum for a fetchRequest
+    /// - Parameters:
+    ///     - predicate: NSPredicate
+    ///     - entityDesc: NSEntityDescription
+    ///     - attributeDesc: NSAttributeDescription
+    ///     - groupBy: NSAttributeDescription? = nil
+    /// - Returns
+    ///     - Result<[[String: Value]], CoreDataRepositoryError>
+    ///
+    public func sum<Value: Numeric>(
+        predicate: NSPredicate,
+        entityDesc: NSEntityDescription,
+        attributeDesc: NSAttributeDescription,
+        groupBy: NSAttributeDescription? = nil
+    ) async -> Result<[[String: Value]], CoreDataRepositoryError> {
+        let _request = request(
+            function: .sum,
+            predicate: predicate,
+            entityDesc: entityDesc,
+            attributeDesc: attributeDesc,
+            groupBy: groupBy
+        )
+        guard entityDesc == attributeDesc.entity else {
+            return .failure(.propertyDoesNotMatchEntity)
+        }
+        return await Self.send(context: context, request: _request)
+    }
+
+    /// Calculate the average for a fetchRequest
+    /// - Parameters:
+    ///     - predicate: NSPredicate
+    ///     - entityDesc: NSEntityDescription
+    ///     - attributeDesc: NSAttributeDescription
+    ///     - groupBy: NSAttributeDescription? = nil
+    /// - Returns
+    ///     - Result<[[String: Value]], CoreDataRepositoryError>
+    ///
+    public func average<Value: Numeric>(
+        predicate: NSPredicate,
+        entityDesc: NSEntityDescription,
+        attributeDesc: NSAttributeDescription,
+        groupBy: NSAttributeDescription? = nil
+    ) async -> Result<[[String: Value]], CoreDataRepositoryError> {
+        let _request = request(
+            function: .average,
+            predicate: predicate,
+            entityDesc: entityDesc,
+            attributeDesc: attributeDesc,
+            groupBy: groupBy
+        )
+        guard entityDesc == attributeDesc.entity else {
+            return .failure(.propertyDoesNotMatchEntity)
+        }
+        return await Self.send(context: context, request: _request)
+    }
+
+    /// Calculate the min for a fetchRequest
+    /// - Parameters:
+    ///     - predicate: NSPredicate
+    ///     - entityDesc: NSEntityDescription
+    ///     - attributeDesc: NSAttributeDescription
+    ///     - groupBy: NSAttributeDescription? = nil
+    /// - Returns
+    ///     - Result<[[String: Value]], CoreDataRepositoryError>
+    ///
+    public func min<Value: Numeric>(
+        predicate: NSPredicate,
+        entityDesc: NSEntityDescription,
+        attributeDesc: NSAttributeDescription,
+        groupBy: NSAttributeDescription? = nil
+    ) async -> Result<[[String: Value]], CoreDataRepositoryError> {
+        let _request = request(
+            function: .min,
+            predicate: predicate,
+            entityDesc: entityDesc,
+            attributeDesc: attributeDesc,
+            groupBy: groupBy
+        )
+        guard entityDesc == attributeDesc.entity else {
+            return .failure(.propertyDoesNotMatchEntity)
+        }
+        return await Self.send(context: context, request: _request)
+    }
+
+    /// Calculate the max for a fetchRequest
+    /// - Parameters:
+    ///     - predicate: NSPredicate
+    ///     - entityDesc: NSEntityDescription
+    ///     - attributeDesc: NSAttributeDescription
+    ///     - groupBy: NSAttributeDescription? = nil
+    /// - Returns
+    ///     - Result<[[String: Value]], CoreDataRepositoryError>
+    ///
+    public func max<Value: Numeric>(
+        predicate: NSPredicate,
+        entityDesc: NSEntityDescription,
+        attributeDesc: NSAttributeDescription,
+        groupBy: NSAttributeDescription? = nil
+    ) async -> Result<[[String: Value]], CoreDataRepositoryError> {
+        let _request = request(
+            function: .max,
+            predicate: predicate,
+            entityDesc: entityDesc,
+            attributeDesc: attributeDesc,
+            groupBy: groupBy
+        )
+        guard entityDesc == attributeDesc.entity else {
+            return .failure(.propertyDoesNotMatchEntity)
+        }
+        return await Self.send(context: context, request: _request)
+    }
+}
+
+// MARK: Extensions
+
+extension NSExpression {
+    /// Convenience initializer for NSExpression that represent an aggregate function on a keypath
+    fileprivate convenience init(
+        function: CoreDataRepository.AggregateFunction,
+        attributeDesc: NSAttributeDescription
+    ) {
+        let keyPathExp = NSExpression(forKeyPath: attributeDesc.name)
+        self.init(forFunction: "\(function.rawValue):", arguments: [keyPathExp])
+    }
+}
+
+extension NSExpressionDescription {
+    /// Convenience initializer for NSExpressionDescription that represent the properties to fetch in NSFetchRequest
+    fileprivate static func aggregate(
+        function: CoreDataRepository.AggregateFunction,
+        attributeDesc: NSAttributeDescription
+    ) -> NSExpressionDescription {
+        let expression = NSExpression(function: function, attributeDesc: attributeDesc)
+        let expDesc = NSExpressionDescription()
+        expDesc.expression = expression
+        expDesc.name = "\(function.rawValue)Of\(attributeDesc.name.capitalized)"
+        expDesc.expressionResultType = attributeDesc.attributeType
+        return expDesc
+    }
+}