Created question in FIWARE Q/A platform on 29-10-2018 at 12:10
Please, ANSWER this question AT https://stackoverflow.com/questions/53044149/how-to-avoid-registrations-result-when-query-the-entities-filtered-by-a-relation

Question:
How to avoid registrations result when query the entities filtered by a relationship

Description:
I've deployed the iot stack with docker. These are the used containers:

fiware/orion:2.0.0
fiware/iotagent-json:1.8.0

[other containers not involved in the issue ...]

Documentation consulted:

http://fiware.github.io/specifications/ngsiv2/stable/

Step 1: I've registered the following entities on the Orion context broker:

curl -X POST \
http://localhost:1026/v2/op/update/ \
-H 'Content-Type: application/json' \
-H 'fiware-service: test' \
-H 'fiware-servicepath: /' \
-d '{
"actionType": "append",
"entities": [{
"type": "Area",
"id": "first:Area:001",
"name":

{ "type": "Text", "value": "First area" }

}, {
"type": "Area",
"id": "second:Area:002",
"name":

{ "type": "Text", "value": "Second area" }

}]
}'

Step 2: I've registered the following device related with the Area first:Area:001 on the IoT agent:

curl -X POST \
http://localhost:4041/iot/devices \
-H 'Content-Type: application/json' \
-H 'fiware-service: test' \
-H 'fiware-servicepath: /' \
-d '{
"devices": [{
"device_id": "device001",
"entity_name": "first:Area:001:IoTDevice:001",
"entity_type": "IoTDevice",
"transport": "HTTP",
"protocol": "IoTA-JSON",
"endpoint": "http://context-producer:3000/iot/iot-device/device001",
"commands": [

{ "name": "ping", "type": "command" }

],
"attributes": [

{ "object_id": "c", "name": "count", "type": "Number" }

],
"static_attributes": [

{ "name": "refArea", "type": "Relationship", "value": "first:Area:001" }

,

{ "name": "name", "type": "Text", "value": "IoT Device 001" }

]
}]
}'

Request 1: When you perform step 2, registration-type entities are automatically generated on the Orion context broker

curl -X GET \
http://localhost:1026/v2/registrations/ \
-H 'fiware-service: test' \
-H 'fiware-servicepath: /'

Result:

[
{
"id": "5bd6dbb2bef7081490c96eb2",
"dataProvided": {
"entities": [

{ "id": "first:Area:001:IoTDevice:001", "type": "IoTDevice" }

],
"attrs": [
"ping"
]
},
"provider": {
"http":

{ "url": "http://iotagent-json:4041" }

,
"supportedForwardingMode": "all",
"legacyForwarding": true
},
"status": "active"
}
]

Test 1: Getting the IoTDevice-type entities related with the Area first:Area:001

curl -X GET \
'http://localhost:1026/v2/entities?options=keyValues&q=refArea==first:Area:001' \
-H 'fiware-service: test' \
-H 'fiware-servicepath: /'

OK Expected Result:

[

{ "id": "first:Area:001:IoTDevice:001", "type": "IoTDevice", "TimeInstant": " ", "count": 0, "name": "IoT Device 001", "ping_info": " ", "ping_status": "UNKNOWN", "refArea": "first:Area:001", "ping": "" }

]

Test 2: Getting the IoTDevice-type entities related with the Area second:Area:001

curl -X GET \
'http://localhost:1026/v2/entities?options=keyValues&q=refArea==second:Area:001' \
-H 'fiware-service: test' \
-H 'fiware-servicepath: /'

ERROR unexpected Result:

[

{ "id": "first:Area:001:IoTDevice:001", "type": "IoTDevice", "ping": "" }

]

The expected result was [ ] or empty but the query returned results that seem to come from the registration-type entities. This only happens if devices with attributes of type command are inserted. For example, the ping command.

So, How can this be avoided?