MBL-1016: Create Paginator for pagination in SwiftUI/Combine #1939
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,83 @@ | ||
| import KsApi | ||
| import SwiftUI | ||
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| private struct PaginationExampleProjectCell: View { | ||
| let title: String | ||
| var body: some View { | ||
| Text(title) | ||
| .padding(.all, 10) | ||
| } | ||
| } | ||
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| private struct PaginationExampleProjectList: View { | ||
| @Binding var projectIdsAndTitles: [(Int, String)] | ||
| @Binding var showProgressView: Bool | ||
| @Binding var statusText: String | ||
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| let onRefresh: () -> Void | ||
| let onDidShowProgressView: () -> Void | ||
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| var body: some View { | ||
| HStack { | ||
| Spacer() | ||
| Text("👉 \(statusText)") | ||
| Spacer() | ||
| } | ||
| .padding(EdgeInsets(top: 20, leading: 0, bottom: 20, trailing: 0)) | ||
| .background(.yellow) | ||
| List { | ||
| ForEach(projectIdsAndTitles, id: \.0) { | ||
| let title = $0.1 | ||
| PaginationExampleProjectCell(title: title) | ||
| } | ||
| if showProgressView { | ||
| HStack { | ||
| Spacer() | ||
| Text("Loading 😉") | ||
|
There was a problem hiding this comment. I noticed a weird bug (?) where |
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| .onAppear { | ||
| onDidShowProgressView() | ||
| } | ||
| Spacer() | ||
| } | ||
| .background(.yellow) | ||
| } | ||
| } | ||
| .refreshable { | ||
| onRefresh() | ||
| } | ||
| } | ||
| } | ||
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| public struct PaginationExampleView: View { | ||
| @StateObject private var viewModel = PaginationExampleViewModel() | ||
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| public var body: some View { | ||
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There was a problem hiding this comment. Note that I very intentionally split up |
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| // Note that PaginationExampleProjectList is decoupled from the view model; | ||
| // all the information it needs is passed in via bindings. | ||
| // This makes it easy to write a preview! | ||
| PaginationExampleProjectList( | ||
| projectIdsAndTitles: $viewModel.projectIdsAndTitles, | ||
| showProgressView: $viewModel.showProgressView, | ||
| statusText: $viewModel.statusText, | ||
| onRefresh: { | ||
| viewModel.didRefresh() | ||
| }, | ||
| onDidShowProgressView: { | ||
| viewModel.didShowProgressView() | ||
| } | ||
| ) | ||
| } | ||
| } | ||
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| #Preview { | ||
| PaginationExampleProjectList( | ||
| projectIdsAndTitles: .constant([ | ||
| (1, "Cool project one"), | ||
| (2, "Cool project two"), | ||
| (3, "Cool project three") | ||
| ]), | ||
| showProgressView: .constant(true), | ||
| statusText: .constant("Example status text"), | ||
| onRefresh: {}, onDidShowProgressView: {} | ||
| ) | ||
| } | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,85 @@ | ||
| import Combine | ||
| import Foundation | ||
| import KsApi | ||
| import Library | ||
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| extension Project: Identifiable {} | ||
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| internal class PaginationExampleViewModel: ObservableObject { | ||
| var paginator: Paginator<DiscoveryEnvelope, Project, String, ErrorEnvelope, DiscoveryParams> | ||
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| @Published var projectIdsAndTitles: [(Int, String)] = [] | ||
| @Published var showProgressView: Bool = true | ||
| @Published var statusText: String = "" | ||
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| init() { | ||
| self.paginator = Paginator( | ||
| valuesFromEnvelope: { | ||
| $0.projects | ||
| }, | ||
| cursorFromEnvelope: { | ||
| $0.urls.api.moreProjects | ||
| }, | ||
| requestFromParams: { | ||
| AppEnvironment.current.apiService.fetchDiscovery_combine(params: $0) | ||
| }, | ||
| requestFromCursor: { | ||
| AppEnvironment.current.apiService.fetchDiscovery_combine(paginationUrl: $0) | ||
| } | ||
| ) | ||
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| self.paginator.$values.map { projects in | ||
| projects.map { ($0.id, $0.name) } | ||
| }.assign(to: &$projectIdsAndTitles) | ||
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| let canLoadMore = self.paginator.$state.map { state in | ||
| state == .someLoaded || state == .unloaded | ||
| } | ||
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| Publishers.CombineLatest(self.paginator.$isLoading, canLoadMore) | ||
| .map { isLoading, canLoadMore in | ||
| isLoading || canLoadMore | ||
| }.assign(to: &$showProgressView) | ||
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| self.paginator.$state.map { [weak self] state in | ||
| switch state { | ||
| case .error: | ||
| let errorText = self?.paginator.error?.errorMessages.first ?? "Unknown error" | ||
| return "Error: \(errorText)" | ||
| case .unloaded: | ||
| return "Waiting to load" | ||
| case .someLoaded: | ||
| let count = self?.paginator.values.count ?? 0 | ||
| return "Got \(count) results; more are available" | ||
| case .allLoaded: | ||
| return "Loaded all results" | ||
| case .empty: | ||
| return "No results" | ||
| } | ||
| } | ||
| .assign(to: &$statusText) | ||
| } | ||
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| var searchParams: DiscoveryParams { | ||
| var params = DiscoveryParams.defaults | ||
| params.staffPicks = true | ||
| params.sort = .magic | ||
| return params | ||
| } | ||
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| func didShowProgressView() { | ||
| if self.paginator.isLoading { | ||
| return | ||
| } | ||
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| if self.paginator.state == .someLoaded { | ||
| self.paginator.requestNextPage() | ||
| } else if self.paginator.state == .unloaded { | ||
| self.paginator.requestFirstPage(withParams: self.searchParams) | ||
| } | ||
| } | ||
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| func didRefresh() { | ||
| self.paginator.requestFirstPage(withParams: self.searchParams) | ||
| } | ||
| } |
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See my note below - the actual display view is just taking simple types. This could take a list of
Projects, and that's what I did originally, but it got a little annoying - I had to useProject.templatein the preview, and that's marked as private toKsApi. So I chose to just keep it to strings-and-ints for now.