srv.before('PATCH, 'entity',...) not being triggered

[protector]

Hello CAP team,

I am attempting to capture a PATCH request within a CAP service that is triggered when fields are changed in a draft mode creation form of an entity. However, I am unable to detect any logs indicating that the PATCH handler has been triggered.

From my service cds file:

@odata.draft.enabled
entity Materials as projection on WNBGReferencesApp.Materials

Output example in console:

[odata] - POST /service/WNBGReferencesApp/$batch 
[odata] - > PATCH Materials(ID=8c8e8a5a-6475-4094-9916-d8eeff98cf32,IsActiveEntity=false)
[odata] - > READ References(ID=e3ff58e7-4e59-4fa1-b258-93e287419560,IsActiveEntity=false)/materials(ID=8c8e8a5a-6475-4094-9916-d8eeff98cf32,IsActiveEntity=false)

PATCH handler:

this.before('PATCH', 'Materials', async(req) => { console.log("Material PATCH IS TRIGGERED") });

I am not sure what I am missing. (I am a beginner)

[Cguttikonda]

Hello,

Patch is considered as UPDATE event, so change the event to Update and try.

[Dinu · Accepted solution]

With lean draft, handlers for PATCH requests to drafts need to be attached to UPDATE of the draft entity. This would be this.entities.Materials.draft in your case.

See documentation.

[protector · Accepted solution]

Thank you the prompt reply.

Could you please elaborate a little more on that?

[Dinu · Accepted solution]

change to:

this.before('UPDATE', 'Materials.drafts', async(req) => { console.log("Material PATCH IS TRIGGERED") });

[protector · Accepted solution]

A legend, thank you much!