Introduce MessageViewModel + Show original translated message
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Sources/StreamChatSwiftUI/ChatChannel/MessageList/MessageContainerView.swift
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Sources/StreamChatSwiftUI/ChatChannel/MessageList/MessageContainerView.swift
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StreamChatSwiftUITests/Tests/ChatChannel/MessageListViewAvatars_Tests.swift
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Sources/StreamChatSwiftUI/ChatChannel/MessageList/MessageViewModel.swift
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| public struct LinkDetectionTextView: View { | ||
| @Environment(\.layoutDirection) var layoutDirection | ||
| @Environment(\.channelTranslationLanguage) var translationLanguage | ||
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| @EnvironmentObject private var viewModel: MessageViewModel |
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This one is a good example that @EnvironmentObject is not a good idea here, since LinkDetectionTextView is likely to be reused as a standalone by other customers.
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Feels like we should go for @StateObject even when it requires making some inits deprecated. Maybe it is time to create a new text view instead? RichTextView or something since the naming does not reflect anymore what it does (does much more than links). New type would allow making bigger changes.
| .onAppear { | ||
| displayedText = attributedString(for: message) | ||
| } | ||
| .onChange(of: message, perform: { updated in | ||
| displayedText = attributedString(for: updated) | ||
| }) |
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I will probably need some help here CC @martinmitrevski @laevandus. This was overriding the view model content always, and was causing some trouble to me. Why is this needed?
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I would like to see not having it here. To be honest, I am not sure why it was needed in the first place.
Sources/StreamChatSwiftUI/ChatChannel/MessageList/MessageView.swift
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| if let displayedText { | ||
| Text(displayedText) | ||
| } else { | ||
| Text(message.adjustedText) | ||
| } |
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In case of LinkDetectionTextView, I'm considering passing a new property, maybe originalText: String? instead of the whole view model, so that it requires less changes. Still need to check if it would work.
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I think there's a simpler way, without using environment object and involving the channel view model.
- we pass the message view model in the MessageContainerView, with default value. We can do that, it's not a breaking change.
- we introduce a state there for each message, whether the show original is tapped for that message.
- customers will implement the existing makeMessageContainer method, by passing their own VM to the regular view.
Let's discuss it when you are back, but I think we can simplify things here a bit.
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| private struct MessageViewModelKey: EnvironmentKey { | ||
| static let defaultValue: MessageViewModel? = nil | ||
| } | ||
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| private struct ChatChannelViewModelKey: EnvironmentKey { | ||
| static let defaultValue: ChatChannelViewModel? = nil | ||
| } |
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These seems to be unused now
🔗 Issue Links
https://linear.app/stream/issue/IOS-794/show-original-translation
https://linear.app/stream/issue/IOS-823/customizing-message-view-display-logic
🎯 Goal
📝 Summary
Goal
The main goal of this PR is to introduce the new
MessageViewModelwhich was required to properly implement the original translated message feature without breaking changes or too many hacks. Besides this, a lot of customers want to override the logic of the Message View, especially when to hide or show some views based on business logic.Requirement
One thing that was important to do was to have a way to share state from the
ChatChannelViewModelto the newMessageViewModel, since theMessageViewModelshould not have any internal state to not cause unnecessary re-renders. Besides that, since the message view is inside a LazyStack, the state would be overidden whenever the view is recreated. So it is important to provide the message view model to each message view whenever it is created.🛠 Implementation
Solution
The most common practice is to have item view models as the data of the
ListViewModel. So instead ofmessages: [ChatMessage]as the data, it would bemessages: [MessageViewModel]. But because of ourLazyCachedMapCollection, and to avoid breaking changes, we can't really do this.The final solution is to create a factory method in the
ChatChannelViewModel, calledmakeMessageViewModel(message:). This approach allows us to pass data from the channel view model to the message view model, ensuring the view model is always updated whenever the view is re-created. The view model is then passed to theMessageContainerViewas an environment object. (Can't be @ObservedObject, otherwise it would be breaking)In order to provide a custom
MessageViewModel, customers will need to subclass theMessageViewModeland override the functionChatChannelViewModel.makeMessageViewModel().🧪 Manual Testing Notes
TODO
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