Validation to disallow multiple create on related entities backed by same database table

ayush3797 commented 2 months ago

Why make this change?

DAB doesn't support multiple-create on related entities which are backed by same database table. This PR adds a validation to catch that scenario and throw a meaningful exception to the end user. Issue to track support: #2157

What is this change?

Adds a validation during order determination logic in MultipleCreateOrderHelper.GetReferencingEntityName() method to catch the scenario.
In the method signature for MultipleCreateOrderHelper.GetReferencingEntityName(), a new parameter isMNRelationship is added with default value of false. The reasoning is explained in the section.

Reason for why `MultipleCreateOrderHelper.GetReferencingEntityName()` is called even for M:N relationships when we know that we are always going to return an empty string?

For M:N relationships, we assume one of the source/target entity as the referencing entity when we do insertion during query execution because any of the entity can be considered as the referencing/referenced entity. However this does not hold true when the source and target entities are backed by same database tables - in which case we cannot consider any of the entity as the referenced/referencing entity.
The not-supported use case - that of not allowing multiple-create via relationships in which source and target entities are backed by same database tables is because DAB cannot determine a valid order of insertion. Since this concerns order determination, it is better to keep the code inside the MultipleCreateOrderHelper.GetReferencingEntityName() method.
Keeping this in MultipleCreateOrderHelper provides unit test coverage even for the other 2 db types i.e. PgSql,MySql.

How was this tested?

Added test MultipleCreateOrderHelperUnitTests.TestExceptionForSelfReferencingRelationships() to test the change for the 3 dbs - MySql/MsSql/PgSql.

Sample Request(s)

Config:

Request:

ayush3797 commented 2 months ago

/azp run

ayush3797 commented 2 months ago

are tests dependent on #2138

Are not dependent. But will require additional entities in the config and some more changes. Keeping bug-bash in mind, trying to get the logic changes in and test can follow.

ayush3797 commented 2 months ago

Now I'm onto adding test.

ayush3797 commented 2 months ago

/azp run

ayush3797 commented 2 months ago

/azp run

ayush3797 commented 2 months ago

/azp run

ayush3797 commented 2 months ago

/azp run

ayush3797 commented 2 months ago

/azp run

Azure / data-api-builder