allow non-numeric meta properties in tedge measurements #3768
Description
Is your feature improvement request related to a problem? Please describe.
Publishing a thin-edge.io measurement which includes non-numeric fragments is not supported where-as the Cumulocity measurement format does support additional meta-information fragments which allows users to contextualize the measurement with additional properties (and avoid those properties being presented as measurements).
tedge mqtt pub 'te/device/main///m/machine_energy_measurement' '{
"robot_mech_energy": {
"accumulated_energy": 0.1,
"ROB_1_axis_1_energy": 0.1,
"ROB_1_axis_2_energy": 0.2,
"ROB_1_axis_3_energy": 0.3,
"ROB_1_axis_4_energy": 0.4,
"ROB_1_axis_5_energy": 0.5,
"ROB_1_axis_6_energy": 0.6,
"ROB_2_axis_1_energy": 0.1,
"ROB_2_axis_2_energy": 0.2,
"ROB_2_axis_3_energy": 0.3,
"ROB_2_axis_4_energy": 0.4,
"ROB_2_axis_5_energy": 0.5,
"ROB_2_axis_6_energy": 0.6
},
"measurement_context": {
"status": "nominal",
"cycle_id": "cycle-98765"
}
}'The above measurement format will result in a parsing error due to the measurement_context fragment containing string values.
$ sudo journalctl -fu tedge-mapper-c8y
Aug 22 09:33:08 tedge tedge-mapper[5392]: 2025-08-22T09:33:08.257174875Z ERROR c8y_mapper_ext::converter: Mapping error: Failed to convert a message on topic 'te/device/main///m/machine_energy_measurement': Invalid JSON: Unexpected type within a group at line 18 column 23: `",
Aug 22 09:33:08 tedge tedge-mapper[5392]: "cycle_id": "cycle-98765"
Aug 22 09:33:08 tedge tedge-mapper[5392]: }
Aug 22 09:33:08 tedge tedge-mapper[5392]: }
Aug 22 09:33:08 tedge tedge-mapper[5392]: `Describe the solution you'd like
Allow users to publish measurements which contain additional non-numeric properties outside of the fragments which contain a value.
- If the user mixes numeric values and non-numeric values under the same property, then the entire property shall be treated as non-numeric property and no measurement conversion should be done on it.
Examples
Example 1
tedge mqtt pub 'te/device/main///m/machine_energy_measurement' '{
"robot_mech_energy": {
"accumulated_energy": 0.1
},
"measurement_context": {
"status": "nominal",
"cycle_id": "cycle-98765"
}
}'Output: Topic: c8y/measurement/measurements/create
{
"robot_mech_energy": {
"accumulated_energy": {
"value": 0.1
}
},
"measurement_context": {
"status": "nominal",
"cycle_id": "cycle-98765"
},
"time": "2025-08-22T09:40:26.979484312Z",
"type": "machine_energy_measurement"
}Example 2
tedge mqtt pub 'te/device/main///m/machine_energy_measurement' '{
"robot_mech_energy": 0.1,
"prop1": "foo",
"prop2": false,
"prop3": ["foo", "bar"]
}'Output: Topic: c8y/measurement/measurements/create
{
"robot_mech_energy": {
"robot_mech_energy": {
"value": 0.1
}
},
"prop1": "foo",
"prop2": false,
"prop3": ["foo", "bar"],
"time": "2025-08-22T09:40:26.979484312Z",
"type": "machine_energy_measurement"
}Example 3
tedge mqtt pub 'te/device/main///m/machine_energy_measurement' '{
"robot_mech_energy": 0.1,
"props": {
"version": 1.2,
"machine_type": "value",
}
}'Note
The props contains both numeric and non-numeric values, however since it has at least one non-numeric value, then the entire property shall be treated as meta information (and not a measurement).
Output: Topic: c8y/measurement/measurements/create
{
"robot_mech_energy": {
"robot_mech_energy": {
"value": 0.1
}
},
"props": {
"version": 1.2,
"machine_type": "value",
}
}Describe alternatives you've considered
Additional context
This request originated from a user-created ticket, #3767