CAP; UPDATE method doesn't trigger READ hanlder after function _readAfterWrite

[alicegavanelli]

Hallo Experts, I have an issue about READ handler.

I have an Entity with calculation fields. In order to set these fields, I have implemented READ handler.

Triggering a GET request everythings is ok: fields are calculated.

Triggering a PUT request in order to modify entity’s data, fields are empty.

CAP after update runs _readAfterWrite function; this function re-loads entity’s data from DB correctly. After this function, CAP should trigger my READ handler, but it doesn’t.

As a result my calculated fields are empty.

Any ideas on how to solve this problem?

Best regards.

Alice

[sergei-u-niq]

you could try putting your code in after-READ, and see if it is triggered then.

Also, you could use same function _setDscriptions in after-UPDATE (same as in after-READ. note that after-READ and on-READ have different parameters)

[alicegavanelli]

Thank you Sergei for you answer.

I have already try to put my code in after-READ and it is triggered only in GET calls.

With PUT calls, CAP triggers after-UPDATE but before function _readAfterWrite so the result is incorrect. Calculeted fields are empty.

Moreover in CAP's documentation you can see this:

[alicegavanelli · Accepted solution]

Thank you Sebastian Van Syckel,

the right answer is:

/*
 * srv/raw-service.js
 */
const cds = require('@sap/cds')

module.exports = async function() {
  const { ReadAfterWrite } = this.entities //> ReadAfterWriteService.ReadAfterWrite
  const DatabaseService = await cds.connect.to('db')
  // register for ReadAfterWriteService.ReadAfterWrite as this is the target of the SELECT query
  DatabaseService.after('each', ReadAfterWrite, (row) => { //> invoked for each row of a READ result
    row.text2 = 'virtual text'
  })
}