Hello Team!
Just out of curiosity...
I'm doing the "Becoming a Reactive Web Developer" course, and I faced this question on a Quiz:
1. Which of the following statements about Entities is FALSE?
A. Entities have attributes.
B. Entities do not require an identifier.
C. Entities are only stored in memory.
D. Entities can be created, updated and deleted.
As is a basic rule that Entities DO require an ID (in fact an ID is created automatically), I quickly choose option B, but that option seems to be wrong and they stated: "That is one of the requirements. They also require at least one other attribute."
I think this is a mistake in the quiz, or am I missing something?
Hi Aldo,
Entities do not require an identifier, so answer B is a TRUE statement.You can try this yourself:
Create a new entity and indeed an identifier is automatically created. After you add an attribute to that entity, you can simply delete the Id and no error whatsoever will be shown and your module will publish just fine.
"That is one of the requirements. They also require at least one other attribute."
This explanation however does seem incorrect. An identifier is required if you want to establish a relationship between two entities but not a requirement perse.
Hope this helps.
Regards,
Nordin
Hi, friend.
Yes, OutSystems allows you to create entity without Id.
For example, I created an entity based on the JSON response of an API. You can create and use, but only the Get method will be available.
Best regards
OH! Perfect,
So now I understand the question, I always thought ID was a must on ENTITIES and that was why IDs were even created automatically.
So in summary, Identity is created automatically, but can be deleted without problems (if an attribute has been created).
Thanks for the quick response and help!
Regards
I was studying for the Reactive exam and just stumbled on this as well.
For some reason, this time, I had the wrong idea, because I am so used to Data Relationship between tables, where everything usually has a relationship with another Entity.
My first thought was "Huh... The non-usage of identifiers is only true if it's a Non Relational database". Which is absolutely wrong.
The correct thought should have been: "The non-usage of identifiers is possible as long as I don't want to create a Relationship dependency with that specific Entity/Table."
Nevertheless, I would like to ask if you guys have examples of where this kind of situations is used within a database, since I can't really visualize that many options where this kind of situation can occur.
Thank you in advance and will also wish a joyful Christmas and New Year ;)