Error while creating deeply nested entity

[Mathias-Storm]

Context:

I am building a CAP application to manage Ressource Rentals. I also created an annotation-based fiori app to go along with it. These are the entities:

entity Resources : managed, cuid {
    name        : String;
    description : String;
    type        : Association to ResourceTypes;
    rentals     : Association to many Rentals
                      on rentals.resource = $self;
}
entity Rentals : managed, cuid {
    resource : Association to Resources;
    start    : DateTime;
    end      : DateTime;
}

And this is the corresponding service:

service ResourceService {
    entity Resources    as projection on my.Resources;
    annotate Resources with @odata.draft.enabled;
    entity Rentals      as projection on my.Rentals;
    annotate Rentals with @odata.draft.enabled;
}

In my Fiori app, i created a list report page and added a table to the ressources.

I linked those to the rentals. This works so far, i can now browse ressources and see their rentals.

Problem:

When i edit a ressource and create a new rental in the rentals table on the object page, i get the following error in CAP:

[cds] - ❗️Uncaught TypeError: Cannot read properties of undefined (reading 'ID')
    at UriHelper.buildEntityKeys (C:\Projects\rentals\node_modules\@sap\cds\libx\_runtime\cds-services\adapter\odata-v4\okra\odata-server\utils\UriHelper.js:85:22)
    at ResponseHeaderSetter.setLocationHeader (C:\Projects\rentals\node_modules\@sap\cds\libx\_runtime\cds-services\adapter\odata-v4\okra\odata-server\core\ResponseHeaderSetter.js:102:17)
    at SetResponseHeadersCommand.execute (C:\Projects\rentals\node_modules\@sap\cds\libx\_runtime\cds-services\adapter\odata-v4\okra\odata-server\invocation\SetResponseHeadersCommand.js:66:30)
    at CommandExecutor._execute (C:\Projects\rentals\node_modules\@sap\cds\libx\_runtime\cds-services\adapter\odata-v4\okra\odata-server\invocation\CommandExecutor.js:71:17)
    at C:\Projects\rentals\node_modules\@sap\cds\libx\_runtime\cds-services\adapter\odata-v4\okra\odata-server\invocation\CommandExecutor.js:81:18
    at ConditionalRequestControlCommand.execute (C:\Projects\rentals\node_modules\@sap\cds\libx\_runtime\cds-services\adapter\odata-v4\okra\odata-server\invocation\ConditionalRequestControlCommand.js:48:5)
    at CommandExecutor._execute (C:\Projects\rentals\node_modules\@sap\cds\libx\_runtime\cds-services\adapter\odata-v4\okra\odata-server\invocation\CommandExecutor.js:71:17)
    at C:\Projects\rentals\node_modules\@sap\cds\libx\_runtime\cds-services\adapter\odata-v4\okra\odata-server\invocation\CommandExecutor.js:81:18
    at C:\Projects\rentals\node_modules\@sap\cds\libx\_runtime\cds-services\adapter\odata-v4\okra\odata-server\invocation\DispatcherCommand.js:88:11
    at process.processTicksAndRejections (node:internal/process/task_queues:95:5) {
  id: '1521876',
  level: 'ERROR',
  timestamp: 1701680136247
}

There is no custom logic associated with the service. I have tried creating one and calling super.init() in the init() callback, but that did not change the behaviour. I also tried extending the before NEW event of a rental to set the ID, which also did not resolve the issue sadly.

So i just decided to delete my custom service logic to just keep the generic event handlers, which still errors.

I exhausted all ideas me and my colleagues had, so id appreciate help 🙂

[Dinu]

You write: When i edit a ressource and create a new rental in the rentals table on the object page.

How did you manage that? The association `rentals` is not a composition. So don't you need to create the rental entity in a separate draft session?

[eric_wu]

https://cap.cloud.sap/docs/cds/cdl#views-with-inferred-signatures

Could you kindly check this, seems the entity in service layer has no {*} to expose the key property.

Best regards,

Eric

[Mathias-Storm]

Hey Eric,

thanks for your quick reply! The key property comes from the CUID aspect, its also visible in the frontend, so it should be accessible.

Or am i misunderstanding what you meant? What exactly should i check?

I appreciate your time, thanks!

[eric_wu]

I mean please check this chapter in cap document https://cap.cloud.sap/docs/cds/cdl#views-with-inferred-signatures .

The key is aspcted by cuid, but this is in db layer, in your service layer, there is no property exposed explicity.