How to attach file to email using REST API - acumatica

Question

I am working with emails from REST API.
I am able to create the email in the system and to update it.
The problem is with attaching files to the email to correct the images in the body of the email.
The endpoint for attaching files to records looks like below:
http://<Base endpoint URL>/<Top-level entity>/<Key value 1>/<Key value 2>/files/<File name>
The problem with emails is that the Key for emails is the NoteID field which can be accessed only using $custom parameter with requests like below:
https://baseurl/18.200.001/Email?$filter=From eq 'test#email.com'&$custom=Message.NoteID
This request will return a response like below
[
{
"id": "50bd83f1-b5bb-49f2-8ca9-6e55d6e10463",
"rowNumber": 1,
"note": "",
...
...
...
"custom": {
"Message": {
"NoteID": {
"type": "CustomGuidField",
"value": "9daca267-4bbd-e911-81ee-0259459e71e6"
}
}
},
"files": []
}
]
Where the NoteID corresponds to the one shown in the browser URL for the email
The problem is that when I try to send a request for attaching a file to that email using that NoteID or id from the response I always receive 'No entity satisfies the condition." error message in the request profiler.
Is there any other way to attach files using REST API?

Answer 1

After reviewing the OpenAPI 2.0 specification, comparing the specification for attaching files to different entities and checking keys of the entities it turned out that the Key of the entity must be specified in the Web Service Endpoint.
In the case of Email entity, the key field is NoteID and it is not specified in the endpoint, even more, it is not being shown in the lookup of the fields in the Web Service Endpoint.
But luckily, the system is allowing to manually write NoteID in the grid and save the endpoint like below:
and this entity is even passing the validation