Chore: update docs to include MacroEvaluator.columns_to_types

[georgesittas]

cc @z3z1ma

[z3z1ma]

Nice 2 questions.

1. Where does this not work. You mention "where columns can be statically determined". Is there any way we can succinctly enumerate a case or two. I have only used the feature on external models thus far. Does it work on other sqlmesh models?

2. Is this there preferred way to get the correct key for the columns_to_types dict? I could see that being a point of contention if it is not clear as you could end up trying to access model_name.this, model_name.key, model_name.alias or who knows. Its obvious enough once you use the lib, but emphasizing the access pattern would be good.

evaluator.columns_to_types(model_name.sql())

cc @georgesittas

[georgesittas]

Thank you for reviewing, @z3z1ma @treysp! Agree with most of the points you've made and will update this PR soon.

[georgesittas]

Nice 2 questions.

1. Where does this not work. You mention "where columns can be statically determined". Is there any way we can succinctly enumerate a case or two. I have only used the feature on external models thus far. Does it work on other sqlmesh models?

2. Is this there preferred way to get the correct key for the columns_to_types dict? I could see that being a point of contention if it is not clear as you could end up trying to access model_name.this, model_name.key, model_name.alias or who knows. Its obvious enough once you use the lib, but emphasizing the access pattern would be good.

evaluator.columns_to_types(model_name.sql())

cc @georgesittas

@z3z1ma regarding (1), IIRC it doesn't work when SQLMesh doesn't know or can't infer the schema of a model. For example, if you don't run create_external_models, then it's supposed to fail if columns_to_types is called with an external model's name for which we don't know the schema.

(2) is probably trickier because it depends on the use-case. If for example a macro gets passed a "foo.bar" then you don't want to generate that arg using .sql() because it'll include the quotes which need to be omitted for the lookup.