BindingAction and @ObservableState Migration in TCA 1.7 #3093

topkim993 · 2024-05-16T02:19:11Z

topkim993
May 16, 2024

I'm in the process of migrating my project to TCA 1.7 and encountered an issue with binding in parent and child states. Here is the relevant code before and after the migration:

The issue arises in the parent reducer after migration. Previously, I could match the binding action on .$isExpanded, but this no longer works with @ObservableState.

How can I correctly handle this binding action with the new @ObservableState in TCA 1.7? Any help or guidance would be greatly appreciated!

before 1.7

// Child
public struct State: Equatable, Identifiable {
    @BindingAction var isExpanded: Bool
}

public enum Action: BindableAction {
    case binding(BindingAction<State>)
}

public var body: some Reducer<State, Action> {
    BindingReducer()
    Reduce { ... }
}

// Parent
public struct State: Equatable, Identifiable {
    var items: IdentifiedArrayOf<ChildFeature.State>
    var childExpansionStateChanged: Bool = true
}

public enum Action: BindableAction {
    case items(IdentifiedActionOf<ChildFeature>)
}

public var body: some Reducer<State, Action> {
    Reduce { state, action in
        switch action {
        case let .items(.element(state, action)):
            switch action {
            case .binding(\.$isExpanded): // ✅ work!
                state.childExpansionStateChanged.toggle()
                return .none
            case .binding:
                return .none
            }
        }
    }
    .forEach(\.items, action: \.items) {
        ChildFeature()
    }
}

after 1.7

// Child
@ObservableState
public struct State: Equatable, Identifiable {
    var isExpanded: Bool
}

public enum Action: BindableAction {
    case binding(BindingAction<State>)
}

public var body: some Reducer<State, Action> {
    BindingReducer()
    Reduce { ... }
}

// Parent
@ObservableState
public struct State: Equatable, Identifiable {
    var items: IdentifiedArrayOf<ChildFeature.State>
    var childExpansionStateChanged: Bool = true
}

public enum Action: BindableAction {
    case items(IdentifiedActionOf<ChildFeature>)
}

public var body: some Reducer<State, Action> {
    Reduce { state, action in
        switch action {
        case let .items(.element(state, action)):
            switch action {
            case .binding(\.$isExpanded): // ❌ Not work
                state.childExpansionStateChanged.toggle()
                return .none
            case .binding:
                return .none
            }
        }
    }
    .forEach(\.items, action: \.items) {
        ChildFeature()
    }
}