compose defaults list dynamically before hydra.main

[blackwint3r]

Not very familiar with hydra yet, not sure if this is a silly questions. Is it possible to compose a defaults list dynamically, before the @hydra.main function is invoked?
In my scenario, I aim to generate a defaults list dynamically based on a specific keyword schema. The objective is to utilize the value associated with schema as a structured configuration schema.

For instance, consider the following config.yaml:

name: John
highschool:
    _schema_: SchoolSchema
    name: CityHigh

And a corresponding schema file named schema/SchoolSchema.yaml:

schoolname: ???
location: RiverCity

The desired outcome would be a configuration that reflects the following structure:

defaults:
    - schema@highschool: SchoolSchema

name: John
highschool:
    name: CityHigh

I want to automatically handle the package path for nested dictionaries, so that I don't have to write a complicated defaults list. But I can't find a suitable place to do this, for the defaults list of DictConfig has already been parsed after hydra.main is called.

[odelalleau]

A few potential options that come to mind:

1. Use the Compose API (if you don't need the extra functionalities offered by hydra.main())
2. If you do need those extra functionalties, you may do it in two steps (use Compose API before calling hydra.main() to generate the final config and dump it to disk first)
3. Maybe hydra-zen can offer some flexible way to achieve this as well (if you're willing to move all your config logic to Python)

[blackwint3r]

thank you for your advice! I'll go investigate