Understanding how Data Graphs utilises identifiers is critical to understanding how to best setup your Datasets and maintain your data.
Key points
- Every Concept (entity) in Data Graphs has an identifier
- The identifier is unique to the class (type) of Concept, for example all Concepts of type Person must have a unique identifier within the scope of all Person Concepts in your Data Graphs project.
- When you create a concept in the UI the identifier field is blank. You can:
- provide an identifier of you choice
- click the gear icon next t the field to generate one
- leave it empty, and Data Graphs will generate an ID automatically when you save the concept
URNs
Internally Data Graphs uses URNs to namespace identifiers by Concept type. A URN is like a URI but is not web resolvable. The URN pattern used in Data Graphs is urn:{project}:{type}:{id} for example urn:test:Person:1a2b3c4d . You will see these URNs when viewing Concept data.
In most circumstances you need not worry about using URNs, especially in the Data Graphs app or when importing data – you can just use the identifier on the end part of the URN. But if you are using the API to query data, the URNs are important as they provide the true identity of each concept.
Manual / Custom identifiers
If when designing your domain model you choose a custom property to be the identifier then Data Graphs cannot generate one for you, and it becomes mandatory you supply these identifiers yourself.
Why might you choose manual IDs? A good example is when you might be importing some external data that already has unique IDs. Or there might be a particular ID pattern you need to use, e.g., the 2 or 3 character ISO-3166 codes for identifying countries:
