Context-Broker not recognizing the mapping of same relationship type to multiple objects using python-ngsild-client about python-ngsild-client

[fbattello]

Dear Miracle,

Fortunately I'm just working on the multiple-attr support.
ETSI specs have changed since I wrote this part of the library.

I've just committed to github.
May be you can try it directly from github : pip install git+https://github.com/Orange-OpenSource/python-ngsild-client

from ngsildclient import *

ctx = [
    "http://example.org/ngsi-ld/latest/commonTerms.jsonld",
    "http://example.org/ngsi-ld/latest/vehicle.jsonld",
    "http://example.org/ngsi-ld/latest/parking.jsonld",
    "https://uri.etsi.org/ngsi-ld/v1/ngsi-ld-core-context-v1.5.jsonld",
]

e = Entity("Vehicle", "A4567", ctx=ctx).prop("brandName", "Mercedes").rel("isParked", ["OffStreetParking:Downtown4", "OffStreetParking:Downtown5", "OffStreetParking:Downtown6"])

That way "object" is not repeated alone but the whole relationship is. Hope it could solve your issue.
You could also pass arrays for metadata.
For example :
e = Entity("Vehicle", "A4567", ctx=ctx).prop("brandName", "Mercedes").rel("isParked", ["OffStreetParking:Downtown4", "OffStreetParking:Downtown5", "OffStreetParking:Downtown6"], datasetid=["source1", "source2", "source3"])

An alternative way is to create a single relationship and then convert to an array.

e = Entity("Vehicle", "A4567", ctx=ctx).prop("brandName", "Mercedes").rel("isParked", "OffStreetParking:Downtown4").rel(Rel.PROVIDED_BY, "Person:Bob", nested=True)
parked = e.arrayify("isParked")
# Update the Python dictionary
parked["object"] = "urn:ngsi-ld:OffStreetParking:Downtown5"
parked["providedBy"]["object"] = "urn:ngsi-ld:Person:Alice"
# Update the entity
e.append("isParked", parked)

Let me know if it's better.
It's still work in progress.

Regards

[Miracle-lab]

Dear Fabien,

First of all thank you for the response. Please I want to inform you that the second alternative which you provided worked fine. However, the "datasetid" with "source1, source2, and source3" is not clear to me. I checked the documentation I could not see a detailed description of its use and function. Please can you provide me with some clarification on these concepts.

Secondly, I tried the first approach you suggested, it was able to create the several mapping to the different object with the same relationship. However, when parsing them to the stellio context broker it generated an error as shown in the image attached below. Thank you.

[fbattello]

Dear Miracle,

Depending on features, brokers have different implementations of the ETSI specifications.
I tested your code against the Orion broker. It works.
But Stellio complains that there are duplicates.
It happens to work by specifying a distinct datasetId field for each attribute (should be optional according to chapter 4.5.5 - Multiple Attribute Support).
You can try this :
e.rel("isParked", ["OffStreetParking:Downtown4", "OffStreetParking:Downtown5", "OffStreetParking:Downtown4"], datasetid=["datasource4", "datasource5", "datasource6"])

[fbattello]

Multiple-Relationship support added in v0.1.10.