How to Register Dialect Correctly for Spring JPA application.

[Aniket-Singla]

@Bean
    public CriteriaBuilderFactory criteriaBuilderFactory() {
        CriteriaBuilderConfiguration config = Criteria.getDefault();
        config.registerDialect("microsoft", new CustomMSSQLDbmsDialect());
        return config.createCriteriaBuilderFactory(entityManagerFactory);
    }

I have followed documentation to register a custom dialect. Problem is that functions are created at the time of Criteria.getDefault() call only and registering custom dialect never helps for microsoft. I have overriden String to use varchar(max) in custom dialect but is not getting picked up in CAST_STRING.

Any help would be appreciated thanks.

Only option I see currently is to rewrite CriteriaBuilderConfigurationImpl.

[beikov]

You could also re-register that one function through a custom CriteriaBuilderConfigurationContributor, but apart from that, this is unfortunately the only way to achieve this.
I'm open to making the DbmsDialect registration more dynamic though so you can achieve what you desire. Can you please explain why you want to use varchar(max) instead? If there is a bug in Blaze-Persistence, we can fix that :)

[Aniket-Singla]

There are two issues with SQL Server Dialect

1. CAST_STRING uses varchar as dtype. varchar in sql server is only 30 chars in length. If I am writing a CONCAT + CAST_STRING combination CAST_STRING trims the output to 30.
2. CONCAT method in microsoft Dialect is set to use PlusBasedConcatFunction. SqlServer supports both but with different behaviour. + does not handles null well. I have overriden the function to use ConcatFunction instead .

Thanks for answering. As you said I am overriding functions itself as overriding Dialect does not help.

I believe first point should be handled as bug fix. Second point might depends on end users but I believe CONCAT function should be made default for sql server.

[beikov]

The semantics of concatenation with null is to produce null which the + operator fulfills. I don't know how the concat function works in SQL Server, but I doubt this is the behavior that we want.
As for 1), I agree that this is a bug. Could you please create a GitHub issue for this and maybe also a PR with a fix? Should be as simple as changing from "varchar" to "varchar(max)"

[Aniket-Singla]

I have opened #1870 as Issue. Will create a PR soon.