Add async Swift Pagination (#382)

* Add async pagination * Add Sendable Tests * Make the Combine paginator generic * Clean up API naming * Allow SequenceProvider to wire errors to the UI * Remove Combine Support (for now) * Reduce `PaginationSequence` init visibility * Remove Combine from Example App * Use paginated users in example app * Lintfix
Automattic · Nov 14, 2024 · 82fc7e3 · 82fc7e3
1 parent 747e860
commit 82fc7e3
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Showing 11 changed files with 291 additions and 59 deletions.
diff --git a/Package.resolved b/Package.resolved
@@ -1,5 +1,5 @@
 {
-  "originHash" : "0385aaff7e0d6e30186b9f42ad615ad3dbcb283b4464c0202bebb483e0b4058f",
+  "originHash" : "9aafa5656d7a6c49905ab42cb52d23fe8b7cefe1a04a14e537053255e511790a",
   "pins" : [
     {
       "identity" : "collectionconcurrencykit",

diff --git a/native/swift/Example/Example.xcodeproj/project.pbxproj b/native/swift/Example/Example.xcodeproj/project.pbxproj
@@ -7,6 +7,7 @@
 	objects = {
 
 /* Begin PBXBuildFile section */
+		242132C82CE69CE80021D8E8 /* WordPressAPI in Frameworks */ = {isa = PBXBuildFile; productRef = 242132C72CE69CE80021D8E8 /* WordPressAPI */; };
 		242D648E2C3602C1007CA96C /* ListViewData.swift in Sources */ = {isa = PBXBuildFile; fileRef = 242D648D2C3602C1007CA96C /* ListViewData.swift */; };
 		242D64922C360687007CA96C /* RootListView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 242D64912C360687007CA96C /* RootListView.swift */; };
 		242D64942C3608C6007CA96C /* ListView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 242D64932C3608C6007CA96C /* ListView.swift */; };
@@ -18,6 +19,7 @@
 		2479BF932B621E9B0014A01D /* ListViewModel.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2479BF922B621E9B0014A01D /* ListViewModel.swift */; };
 		24A3C32F2BA8F96F00162AD1 /* LoginView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 24A3C32E2BA8F96F00162AD1 /* LoginView.swift */; };
 		24A3C3362BAA874C00162AD1 /* LoginManager.swift in Sources */ = {isa = PBXBuildFile; fileRef = 24A3C3352BAA874C00162AD1 /* LoginManager.swift */; };
+		24E77D032CE44DD900F6998C /* WordPressAPI in Frameworks */ = {isa = PBXBuildFile; productRef = 24E77D022CE44DD900F6998C /* WordPressAPI */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXFileReference section */
@@ -41,6 +43,8 @@
 			buildActionMask = 2147483647;
 			files = (
 				2479BF912B621CCA0014A01D /* WordPressAPI in Frameworks */,
+				242132C82CE69CE80021D8E8 /* WordPressAPI in Frameworks */,
+				24E77D032CE44DD900F6998C /* WordPressAPI in Frameworks */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
@@ -123,6 +127,8 @@
 			name = Example;
 			packageProductDependencies = (
 				2479BF902B621CCA0014A01D /* WordPressAPI */,
+				24E77D022CE44DD900F6998C /* WordPressAPI */,
+				242132C72CE69CE80021D8E8 /* WordPressAPI */,
 			);
 			productName = Example;
 			productReference = 2479BF7D2B621CB60014A01D /* Example.app */;
@@ -153,7 +159,7 @@
 			);
 			mainGroup = 2479BF742B621CB60014A01D;
 			packageReferences = (
-				2479BF8F2B621CCA0014A01D /* XCLocalSwiftPackageReference "../../.." */,
+				242132C62CE69CE80021D8E8 /* XCLocalSwiftPackageReference "../../../../wordpress-rs" */,
 			);
 			productRefGroup = 2479BF7E2B621CB60014A01D /* Products */;
 			projectDirPath = "";
@@ -409,17 +415,25 @@
 /* End XCConfigurationList section */
 
 /* Begin XCLocalSwiftPackageReference section */
-		2479BF8F2B621CCA0014A01D /* XCLocalSwiftPackageReference "../../.." */ = {
+		242132C62CE69CE80021D8E8 /* XCLocalSwiftPackageReference "../../../../wordpress-rs" */ = {
 			isa = XCLocalSwiftPackageReference;
-			relativePath = ../../..;
+			relativePath = "../../../../wordpress-rs";
 		};
 /* End XCLocalSwiftPackageReference section */
 
 /* Begin XCSwiftPackageProductDependency section */
+		242132C72CE69CE80021D8E8 /* WordPressAPI */ = {
+			isa = XCSwiftPackageProductDependency;
+			productName = WordPressAPI;
+		};
 		2479BF902B621CCA0014A01D /* WordPressAPI */ = {
 			isa = XCSwiftPackageProductDependency;
 			productName = WordPressAPI;
 		};
+		24E77D022CE44DD900F6998C /* WordPressAPI */ = {
+			isa = XCSwiftPackageProductDependency;
+			productName = WordPressAPI;
+		};
 /* End XCSwiftPackageProductDependency section */
 	};
 	rootObject = 2479BF752B621CB60014A01D /* Project object */;

diff --git a/native/swift/Example/Example/ExampleApp.swift b/native/swift/Example/Example/ExampleApp.swift
@@ -1,5 +1,9 @@
 import SwiftUI
 import WordPressAPI
+import Combine
+
+private let userListParams = UserListParams(perPage: 5)
+private let postListParams = PostListParams(perPage: 5)
 
 @main
 struct ExampleApp: App {
@@ -13,9 +17,9 @@ struct ExampleApp: App {
                 .data
                 .map { $0.asListViewData }
         }),
-        RootListData(name: "Users", callback: {
-            try await WordPressAPI.globalInstance.users.paginatedWithEditContext(params: UserListParams(perPage: 100))
-                .map { $0.asListViewData }
+        RootListData(name: "Users", sequence: {
+            let sequence = try WordPressAPI.globalInstance.users.sequenceWithEditContext(params: userListParams)
+            return ListViewSequence(underlyingSequence: sequence)
         }),
         RootListData(name: "Plugins", callback: {
             try await WordPressAPI.globalInstance.plugins.listWithEditContext(params: .init())
@@ -27,9 +31,9 @@ struct ExampleApp: App {
                 value.asListViewData
             }
         }),
-        RootListData(name: "Posts", callback: {
-            try await WordPressAPI.globalInstance.posts.paginatedWithEditContext(params: PostListParams(perPage: 100))
-                .map { $0.asListViewData }
+        RootListData(name: "Posts", sequence: {
+            let sequence = try WordPressAPI.globalInstance.posts.sequenceWithEditContext(params: postListParams)
+            return ListViewSequence(underlyingSequence: sequence)
         }),
         RootListData(name: "Site Health Tests", callback: {
             let items: [any ListViewDataConvertable] = [

diff --git a/native/swift/Example/Example/ListViewData.swift b/native/swift/Example/Example/ListViewData.swift
@@ -1,11 +1,16 @@
 import Foundation
 import WordPressAPI
+import WordPressAPIInternal
 
-struct ListViewData: Identifiable {
+struct ListViewData: Identifiable, Comparable, Hashable {
     let id: String
     let title: String
     let subtitle: String
     let fields: [String: String]
+
+    static func < (lhs: ListViewData, rhs: ListViewData) -> Bool {
+        lhs.title < rhs.title
+    }
 }
 
 protocol ListViewDataConvertable: Identifiable {
@@ -151,3 +156,15 @@ extension PostWithEditContext: ListViewDataConvertable {
         ListViewData(id: self.id, title: self.title.raw, subtitle: self.slug, fields: [:])
     }
 }
+
+extension [PostWithEditContext] {
+    func asListViewData() -> [ListViewData] {
+        self.map { $0.asListViewData }
+    }
+}
+
+extension [ListViewDataConvertable] {
+    func asListViewData() -> [ListViewData] {
+        self.map { $0.asListViewData }
+    }
+}
diff --git a/native/swift/Example/Example/ListViewModel.swift b/native/swift/Example/Example/ListViewModel.swift
@@ -2,46 +2,83 @@ import Foundation
 import SwiftUI
 import WordPressAPI
 
-@Observable class ListViewModel {
+@MainActor
+protocol ListViewModel {
+
+    /// Guarantee only one object with each ID, but allow updating the object when new data comes in
+    var listItems: [String: ListViewData] { get }
+
+    var shouldPresentAlert: Bool { get set }
+
+    var error: MyError? { get set }
+
+    func task() async
+}
+
+@Observable class SequenceListViewModel: ListViewModel {
+    var listItems: [String: ListViewData] = [String: ListViewData](minimumCapacity: 250)
+
+    typealias SequenceProvider = () throws -> ListViewSequence
+
+    private let sequenceProvider: SequenceProvider
+
+    init(sequenceProvider: @escaping SequenceProvider) {
+        self.sequenceProvider = sequenceProvider
+    }
+
+    var shouldPresentAlert: Bool = false
+
+    var error: MyError?
+
+    var sequence: ListViewSequence?
+
+    func task() async {
+        do {
+            for try await page in try self.sequenceProvider() {
+                for item in page {
+                    self.listItems[item.id] = item
+                }
+            }
+        } catch {
+            self.error = .init(underlyingError: error)
+            self.shouldPresentAlert = true
+        }
+    }
+
+    func reset() {
+
+    }
+}
+
+@Observable class TaskListViewModel: ListViewModel {
 
     typealias FetchDataTask = () async throws -> [ListViewData]
 
-    var listItems: [ListViewData] = []
+    var listItems: [String: ListViewData] = [:]
     private var dataCallback: FetchDataTask
-    private var dataTask: Task<Void, any Error>?
     var isLoading: Bool = false
 
     var error: MyError?
     var shouldPresentAlert = false
 
-    let loginManager: LoginManager
-
-    init(loginManager: LoginManager, dataCallback: @escaping FetchDataTask) {
-        self.loginManager = loginManager
+    init(dataCallback: @escaping FetchDataTask) {
         self.dataCallback = dataCallback
     }
 
-    func startFetching() {
-        self.error = nil
+    func task() async {
+        self.isLoading = true
         self.shouldPresentAlert = false
 
-        self.dataTask = Task { @MainActor in
-            self.isLoading = true
-            self.shouldPresentAlert = false
-
-            do {
-                self.listItems = try await dataCallback()
-            } catch {
-                self.error = MyError(underlyingError: error)
-                self.shouldPresentAlert = true
+        do {
+            for item in try await dataCallback() {
+                listItems[item.id] = item
             }
-
-            self.isLoading = false
+        } catch {
+            self.error = MyError(underlyingError: error)
+            self.shouldPresentAlert = true
         }
-    }
 
-    func stopFetching() {
-        self.dataTask?.cancel()
+        self.isLoading = false
     }
 }
 
@@ -60,3 +97,34 @@ struct MyError: LocalizedError {
         underlyingError.localizedDescription
     }
 }
+
+struct ListViewSequence: AsyncSequence {
+    typealias Element = [ListViewData]
+
+    private let underlyingSequence: any AsyncSequence
+
+    init(underlyingSequence: any AsyncSequence) {
+        self.underlyingSequence = underlyingSequence
+    }
+
+    struct ListViewIterator: AsyncIteratorProtocol {
+        var underlyingSequence: any AsyncIteratorProtocol
+
+        mutating func next() async throws -> Element? {
+            guard let nextElement = try await underlyingSequence.next() else {
+                return nil
+            }
+
+            guard let listViewData = nextElement as? [any ListViewDataConvertable] else {
+                debugPrint("Unable to convert data to `ListViewDataConvertable`")
+                return nil
+            }
+
+            return listViewData.asListViewData()
+        }
+    }
+
+    func makeAsyncIterator() -> ListViewIterator {
+        ListViewIterator(underlyingSequence: underlyingSequence.makeAsyncIterator())
+    }
+}
diff --git a/native/swift/Example/Example/UI/ListView.swift b/native/swift/Example/Example/UI/ListView.swift
@@ -6,7 +6,7 @@ struct ListView: View {
     var viewModel: ListViewModel
 
     var body: some View {
-        List(viewModel.listItems) { item in
+        List(viewModel.listItems.values.sorted(), id: \.id) { item in
             VStack(alignment: .leading) {
                 Text(item.title).font(.headline)
                 Text(item.subtitle).font(.footnote)
@@ -29,14 +29,15 @@ struct ListView: View {
                 }
             }
         )
-        .onAppear(perform: viewModel.startFetching)
-        .onDisappear(perform: viewModel.stopFetching)
+        .task {
+            await viewModel.task()
+        }
     }
 }
 
 #Preview {
 
-    let viewModel = ListViewModel(loginManager: LoginManager(), dataCallback: {
+    let viewModel = TaskListViewModel(dataCallback: {
         [
             ListViewData(id: "1234", title: "Item 1", subtitle: "Subtitle", fields: [:])
         ]

diff --git a/native/swift/Example/Example/UI/RootListView.swift b/native/swift/Example/Example/UI/RootListView.swift
@@ -1,5 +1,6 @@
 import SwiftUI
 import WordPressAPI
+import Combine
 
 struct RootListView: View {
 
@@ -16,28 +17,50 @@ struct RootListViewItem: View {
     let item: RootListData
 
     var body: some View {
-        VStack(alignment: .leading, spacing: 4.0) {
-            NavigationLink {
-                ListView(
-                    viewModel: ListViewModel(
-                        loginManager: LoginManager(),
-                        dataCallback: self.item.callback
+        switch item {
+        case .callback(let name, let fetchDataTask):
+            VStack(alignment: .leading, spacing: 4.0) {
+                NavigationLink {
+                    ListView(
+                        viewModel: TaskListViewModel(dataCallback: fetchDataTask)
                     )
-                )
-            } label: {
-                Text(item.name)
+                } label: {
+                    Text(name)
+                }
+            }
+
+        case .sequence(let name, let sequenceProvider):
+            VStack(alignment: .leading, spacing: 4.0) {
+                NavigationLink {
+                    ListView(
+                        viewModel: SequenceListViewModel(sequenceProvider: sequenceProvider)
+                    )
+                } label: {
+                    Text(name)
+                }
             }
         }
     }
 }
 
-struct RootListData: Identifiable {
+enum RootListData: Identifiable {
 
-    let name: String
-    let callback: ListViewModel.FetchDataTask
+    case callback(String, TaskListViewModel.FetchDataTask)
+    case sequence(String, SequenceListViewModel.SequenceProvider)
 
     var id: String {
-        self.name
+        switch self {
+        case .callback(let id, _): id
+        case .sequence(let id, _): id
+        }
+    }
+
+    init(name: String, callback: @escaping TaskListViewModel.FetchDataTask) {
+        self = .callback(name, callback)
+    }
+
+    init(name: String, sequence: @escaping SequenceListViewModel.SequenceProvider) {
+        self = .sequence(name, sequence)
     }
 }