Here is my models:

import SwiftData

@Model
final public class FirstModel {
    let name: String

    @Relationship(deleteRule: .cascade, inverse: SecondModel.parent) var children = [SecondModel]()

    init(name: String) {
        self.name = name
    }
}

@Model
final public class SecondModel {
    let parent: FirstModel
    let name: String

    @Relationship(deleteRule: .cascade, inverse: ThirdModel.parent) var children = [ThirdModel]()

    init(name: String, parent: FirstModel) {
        self.name = name
        self.parent = parent
    }
}

@Model
final public class ThirdModel {
    let parent: SecondModel
    let name: String

    init(name: String, parent: SecondModel) {
        self.name = name
        self.parent = parent
    }
}

Then I create my model entries:

let schema = Schema([
    FirstModel.self,
    SecondModel.self,
    ThirdModel.self
])

let container = try ModelContainer(for: schema)
let context = ModelContext(container)

let firstModel = FirstModel(name: "my first model")
let secondModel = SecondModel(name: "my second model", parent: firstModel)
let thirdModel = ThirdModel(name: "my third model", parent: secondModel)

context.insert(firstModel)
context.insert(secondModel)
context.insert(thirdModel)

try context.save()

I want to retrieve the children from my models:

print("-- Fetch Third Model")
let thirdFetchDescriptor: FetchDescriptor<ThirdModel> = FetchDescriptor<ThirdModel>(predicate: #Predicate { $0.name == "my third model" })
let thirdModels = try context.fetch(thirdFetchDescriptor)
for entry in thirdModels {
    print(">>> (entry) - (entry.parent) - (entry.parent.parent)")
}

print("-- Fetch First Model")
let firstFetchDescriptor: FetchDescriptor<FirstModel> = FetchDescriptor<FirstModel>(predicate: #Predicate { $0.name == "my first model" })
let firstModels = try context.fetch(firstFetchDescriptor)
for entry in firstModels {
    print(">>> (entry) - (entry.children)")
    for child in entry.children {
        print("t>>> (child) - (child.children)")
    }
}

… But it does not seem to work:

-- Fetch Third Model
>>> cardapart_sdk_app_ui.ThirdModel - cardapart_sdk_app_ui.SecondModel - cardapart_sdk_app_ui.FirstModel

-- Fetch First Model
>>> cardapart_sdk_app_ui.FirstModel - []

I am not sure what I am doing wrong or missing…