Im creating expenses app with by using 2 different Model Transaction and Category Model. and always failed to add category to the transaction

Question

im pretty new on the SwiftUI so I dont how face this issue. Currently im creating expense app for my learning. Im still not understand how the model works. in this case I have 2 different model Transaction and Category

@Model
class TransactionModel{
    
    @Attribute(.unique) var id: String
    var amount: Float
    var creationDate: Date
    var notes: String
    @Relationship var categoryTrxs: CategoryModel?
    
    init(amount: Float, creationDate: Date, notes: String, categoryTrx: CategoryModel) {
        self.id = UUID().uuidString
        self.amount = amount
        self.creationDate = creationDate
        self.notes = notes
        self.categoryTrxs = categoryTrxs
    }
}

@Model
class CategoryModel{
    
    @Attribute(.unique)
    var id: String
    @Attribute(.transient)
    var isChecked = false
    var name: String
    var emoji: String
    var colors: String
    
    
    @Relationship(inverse: \TransactionModel.categoryTrxs)
    var trxs: [TransactionModel]?
    
    init(name: String, emoji: String, colors: String) {
        self.id = UUID().uuidString
        self.name = name
        self.emoji = emoji
        self.colors = colors

    }
    
}

This how I trying to save the transaction

@Environment(\.presentationMode) var presentationMode
@Environment (\.modelContext) private var context
@Query private var allCategory : [CategoryModel]
@Query private var allTrx: [TransactionModel]
 
@State private var isPopoverCategoryShows = false
@State private var selectedCategoryId = ""
@State private var amountString: String = "0"
@State private var date = Date()

.....

private var addTrxButton: some View{
    PrimaryButton(text: "Add") {
       
        var categoryGrabber: CategoryModel?

        // Find the selected category using its ID
        if let selectedCategory = allCategory.first(where: { $0.id == selectedCategoryId }) {
            categoryGrabber = selectedCategory
        }

        // Check if a category was found before creating the transaction
        if let category = categoryGrabber {
            let expenses = TransactionModel(amount: Float(amountString) ?? 0.0,
                                            creationDate: Date(),
                                            notes: "Test",
                                            categoryTrx: category)

            context.insert(expenses)
            
            do {
                try context.save()
                print("Transaction Added")
                print(expenses.categoryTrxs?.name ?? "None"," with Total amount ") // -> rendered as None 
                print(expenses.amount)  // -> rendered as correct amount 
                print(category.name) // -> rendered as correct category
            } catch {
                print(error.localizedDescription)
            }
        } else {
            print("Selected category not found.")
        }

            
    }
} 

The problem is when I tried to create a transaction/expense seems like the category is not attached to the Transaction. The expenses is added but the category is not there

enter image description here