Regression: LIKE queries on nullable fields in MySQL

[thomasmost]

Regression: LIKE queries on nullable fields in MySQL

[weiznich]

Thanks for reporting and good job for noticing that ~2h after the relevant change was merged 👍

I think we just miss the relevant impl for nullable here:

diesel/diesel/src/expression/operators.rs

Line 749 in 6ef23bd

impl<DB> LikeIsAllowedForType<crate::sql_types::Text> for DB where DB: Backend {}

I think I would likely write something like that:

impl<T, DB> LikeIsAllowedForType<crate::sql_types::Nullable<T>> for DB 
where 
    DB: Backend + LikeIsAllowedForType<T>,  
{} 

That also should cover Nullable<Binary> for the postgres backend.

Mind sumitting a PR that adds this impl + adds a test so that we don't break it again?

[weiznich]

https://github.com/diesel-rs/diesel/blob/master/diesel_tests/tests/filter.rs would be a good place for the test. I think the users table there already has a nullable text field.

[thomasmost]

Would be happy to :)

[thomasmost]

@weiznich I think I can figure out how to write the test, but can you point me to the workspace member library where the test should go?

[thomasmost]

Thank you!