How to access the state inside the .forEach?

[MojtabaHs]

Suppose I had a Single Feature that works perfectly with a single shared dependency.

After a while, I decided to make more of that single feature as children of a parent.

So now I have something like:

        Reducer { state, action in
            parentReduce(into: &state, action: action)
        }
        .forEach(
            \.child,
             action: /Action.child
        ) {
            ChildFeature()
                .dependency(\.notSharedDependency, .init(state.something)) // 👈 the point is here, state is not available here
        }

So how can I access the state of each child during the .forEach so I can pass in the correct dependency?

Is this a good idea in the first place?

How about passing the first two arguments into the ReducerBuilder as the original ForEach does in the SwiftUI?

I really appreciate any help you can provide.

[pyrtsa]

Not part of TCA yet, but this would be the prime use case for reducer readers: #1969

In the meantime, you could implement it by manually handling the child reducer wrapping the same way (i.e. by manually calling reduce(into:action:) on the child reducer from the parent in a dependency injection context).

[MojtabaHs]

I see! Looking forward to updates on that PR.

By the way, When I use the ReducerReader for the child inside the forEach, the compiler breaks and raise Ambiguous use of <something irrelevant> 🤦🏻‍♂️

        Reducer { state, action in  // 👈 Compiler marks here as Ambiguous
            parentReduce(into: &state, action: action)
        }
        .forEach(
            \.child,
             action: /Action.child
        ) {
          ReducerReader { state, action in  // 👈 When using the `ReducerReader` here
            ChildFeature()
                .dependency(\.notSharedDependency, .init(state.something))
          }
        }

But when I use it on the parent, the compiler is satisfied but it forces me to use undesired if let case in the parent's state to find the proper child's state.

P.S.: I don't know why but it seems like the dependency override does not work at all and it always uses the liveValue, Even by passing a hard-coded value like:

ChildFeature()
    .dependency(\.notSharedDependency, .init("HARD-CODED STUFF HERE")

[pyrtsa]

If you seem to get the liveValue in your child reducer no matter what, one common mistake could be if you're deriving the child store using Store.init(initialState:reducer:) instead of scope(state:action:) in your views.

[MojtabaHs]

Any idea about the ambiguity?

[fabstu]

You could try changing the second state, action to different names. Not sure though. I tried putting ReducerReader inside Scope before and had issues as well, but I don't remember anymore exactly what it was.

[MojtabaHs]

Turns out is because the ReducerReader's initializer and Xcode were pointing to an invalid location of the code (like always!).

So changing:

ReducerReader { state, action in

To this:

ReducerReader.init({ state, action in

Does the job and removes the ambiguity.

[MojtabaHs]

Turns out this old drafted PR is exactly what I need.

Closing this discussion in favor of that.