Hello experts,

I'm having a problem with a rather particular schema: I have a table (DocumentItem) which represents all the items that are in "DocumentHeader". The primary keys are:

- DocumentHeader -> DocumentId

- DocumentItem -> DocumentId * (foreign key) and ItemNumber

The problem comes when in another table I need DocumentId (taken from DocumentHeader) and ItemNumber (taken from DocumentItem) as foreign keys. I also need that the ItemNumber is correctly associated with the DocumentID, as declared in the "DocumentItem" table

The problem in question is that it doesn't show me when I go to insert "ItemNumber" mock data, going to show it only if I remove the "key" property.

Thanks to all, I am available for clarification

general schema:

schema.cds

entity DocumentHeader
{
    key DocumentId : String
        @Core.Computed;
    Status : String(100) not null;
    CustomerId : String(100) not null;
    TotalValue : Double not null;
    Currency : String(100) not null;
    TotalQuantity : Double not null;
    UoM : String(100) not null;
    to_DeliveryAddress : Association to one Customer
        @assert.integrity;
    DocumentDate : String(100) not null;
    CustomerOrder : String(100) not null;
    RequestDeliveryDate : String(100) not null;
    EffectiveDeliveryDate : String(100) not null;
    DeliveryStatus : String(100) not null;
    DeliveryBloc : String(100) not null;
    IncoiceBloc : String(100) not null;
    PayConditions : String(100) not null;
    ShipToPartnerId : String(100) not null;
    to_DocumentItems : Association to many DocumentItem
        @assert.integrity;
    to_Partners : Association to many Partner on to_Partners.DocumentId = $self
        @assert.integrity;
    to_PriceConditions : Association to many PriceCondition on to_PriceConditions.DocumentId = $self
        @assert.integrity;
    to_DeliveryPlans : Association to many DeliveryPlan on to_DeliveryPlans.DocumentId = $self
        @assert.integrity;
    to_Notes : Association to many Note on to_Notes.DocumentId = $self;
}

entity Note
{
    key NoteType : String
        @Core.Computed;
    NoteDesc : String(100) not null;
    NoteText : String(100) not null;
    key ItemNumber : Association to one DocumentItem
        @assert.integrity;
    DocumentId : Association to one DocumentHeader;
}

entity DocumentItem
{
    key ItemNumber : String
        @Core.Computed;
    ProductId : String(100) not null;
    Quantity : Double not null;
    UoM : String(100) not null;
    Price : Double not null;
    Currency : String(100) not null;
    Discounts : Double not null;
    TotalValue : Double not null;
    ItemStatus : String(100) not null;
    Incoterms : String(100) not null;
    EffectiveGoodIssue : String(100) not null;
    DeliveryStatus : String(100) not null;
    ItemCategory : String(100) not null;
    BatchStatus : String(100) not null;
    ATPDate : String(100) not null;
    key DocumentId : Association to one DocumentHeader
        @assert.integrity;
    to_Partners : Association to many Partner on to_Partners.ItemNumber = $self
        @assert.integrity;
    to_PriceConditions : Association to many PriceCondition on to_PriceConditions.ItemNumber = $self
        @assert.integrity;
    to_DeliveryPlans : Association to many DeliveryPlan on to_DeliveryPlans.ItemNumber = $self
        @assert.integrity;
    to_Notes : Association to many Note on to_Notes.ItemNumber = $self;
}

Mock Data ("ItemNumber" is missing):