SAP-samples/cloud-cap-samples

Many-many association example

Nandanchaturvedi opened this issue · 5 comments

Nandanchaturvedi commented

Hi colleagues

I request you to provide a working example showing many-many relation in CAP. This seems to be a fundamental requirement for any business application and I dont see any documentation describing it for reference.

Request you to share.

Nandanchaturvedi commented

Hi @David-Kunz ,

I would request if there is an example which you can share. I referred the documentation but facing some issues as I opened another issue in the Github earlier for the same.

Do you have a repo showing working example with many-many

David-Kunz commented

HI @Nandanchaturvedi ,

Unfortunately, I don't have a concrete example, but did you try the example from the documentation?

entity Authors { ...
  books : Association to many Books2Authors on books.author = $self;
}
entity Books { ...
  author : Association to many Books2Authors on author.book = $self;
}
entity Books2Authors { ...
  book : Association to Books;
  author : Association to Authors;
}

Best regards,
David

Nandanchaturvedi commented

Hi @David-Kunz ,

Yes, I did try this but not sure how this would work in the context of creation and in Fiori.

Following is the error I get if I try the deep insert.
While I try to make all IDs Guid, I get the following error:

{
"error": {
"code": "400",
"message": "Deep insert with to-many Associations is not allowed"
}
}

This is how the model looks like:

entity PfgRequests : managed, cuid {
contacts : Association to many PfgContacts on contacts.pfgRequest = $self;
}
entity Contacts : cuid {
pfgRequests : Association to many PfgContacts on pfgRequests.contact = $self;
}

entity PfgContacts { //maintains many-many entity
key pfgRequest: Association to PfgRequests;
key contact: Association to Contacts;
}

And I have exposed all three in the service

David-Kunz commented

Hi @Nandanchaturvedi ,

It's not allowed to deep insert too many associations.

You need to do the posts on each entity.

Best regards,
David