Support Multitenancy via discriminator column

[sdelamo]

Micronaut Data currently supports multi-tenancy via datasource or schema. Not sure how the API should look like for column discriminator multi tenancy .

But I assume something like:

@MappedEntity // (1)
record Book(
        @Id @GeneratedValue @Nullable Long id,
        @DateCreated @Nullable Date dateCreated,
       @TenantId String publisher,
        String title,
        int pages) {
}

and a JdbcRepository

@JdbcRepository(dialect = Dialect.H2
interface BookRepository extends CrudRepository<Book, Long> {

for bookRepository.findAll() we should do select * from book where publisher = 'xxx'.

We should leverage Micronaut Multitenancy for tenant resolution.

See GORM Multi-tenancy API for ideas.

[sdelamo]

@graemerocher @dstepanov @radovanradic thoughts?

[dstepanov]

To implement it, first, we need to support query parameters resolved outside of the method scope.
My idea is to support syntax: select * from users where my_column = #outside_param and my_id = :methodParameter and add some info about it to io.micronaut.data.model.runtime.QueryParameterBinding.
We can support a simple bean interface to resolve global parameters by name: QueryParameterResolver#tryResolve(String) or even support defining special resolvers like TenantQueryParameterResolver

[dstepanov]

@TenantId can be implemented as an annotation annotated with something like @RuntimeQueryParameter(resolver = TenantResolver.class)

[graemerocher]

wouldn't it be better to support the expression language? You could then at an expression context to resolve the current tenant

[dstepanov]

Maybe, but that is a bit more complex and can be added later.

[graemerocher]

Ok, for me personally it doesn't make sense to introduce another overloaded syntax #outside_param for the # character when that is already used for the expression language. It will just confuse users.

[sdelamo]

I agree with @graemerocher I think we should aim to support the expression language in Micronaut Data queries.

I created an issue to support the expression language for tenant resolution.

[dstepanov]

I'm a bit afraid to support all that #{..} syntax in SQL queries