Unique constraint on data and datalink
- make the datalink and data unique together
- Endpoint "POST"
datalink
- Verification that dataLink with the same data and node:
- 200 return the existing one
- 201 create a new one
- Verification that dataLink with the same data and node:
- Endpoint "POST"
data
- Verification that data with the same external_id:
- 200 return the existing one
- 201 create a new one
- Verification that data with the same external_id: