Changes to dispatch in dbt v0.20

Hey Teghan! I wanted to give you a heads up about a change coming in the next version of dbt. Let me know if you have questions, I'm happy to help.

Required code change

We've made a change to adapter.dispatch: Instead of passing a _get_namespaces() macro to the packages arg, you should pass the name of this package (as a string) to the macro_namespace arg, which is now the second positional argument.

dbt-meta-testing/macros/fetch_configured_models.sql

Lines 1 to 3 in cd1cb2b

    
           {% macro fetch_configured_models(meta_config, models=none, resource_type="model") %} 
        
           	{{ return(adapter.dispatch("fetch_configured_models", packages=dbt_meta_testing._get_meta_test_namespaces())(meta_config, models, resource_type)) }} 
        
           {% endmacro %}

To:

{% macro fetch_configured_models(meta_config, models=none, resource_type="model") %}
	{{ return(adapter.dispatch("fetch_configured_models", "dbt_meta_testing")(meta_config, models, resource_type)) }}
{% endmacro %}

I hope this could be as simple as Find + Replace for packages=dbt_meta_testing._get_meta_test_namespaces() → "dbt_meta_testing".

If you prefer more explicit syntax, you could also make this:

{% macro fetch_configured_models(meta_config, models=none, resource_type="model") %}
	{{ return(adapter.dispatch(macro_name = "fetch_configured_models", macro_namespace = "dbt_meta_testing")(meta_config, models, resource_type)) }}
{% endmacro %}

For the README

If a user wishes to override/shim this package, instead of defining a var named dbt_meta_test_dispatch_list, they should now define a config in dbt_project.yml, for instance:

dispatch:
  - macro_namespace: dbt_meta_testing
    search_order: ['my_project', 'dbt_meta_testing']  # enable override

Notes

This change is in dbt v0.19.2 as well. Both v0.19.2 and v0.20.0 have backwards compatibility for the old syntax, so there's no huge rush to upgrade.

However:

The old syntax will start raising a deprecation warning in v0.20
The var name in this package, dbt_meta_test_dispatch_list, varies just slightly from the convention established by other packages. The backwards-compatibility logic we added to dbt would instead expect dbt_meta_testing_dispatch_list. If you know other folks are relying on this functionality to override/shim this package, we can hard code logic that looks for dbt_meta_test_dispatch_list IFF the dispatching package is dbt_meta_testing.

As soon as you do upgrade to the new syntax, you'll need to require dbt >= 0.19.2 (or just >=0.20.0, for simplicity, since you're already making compatibility changes in #69).

	{% macro fetch_configured_models(meta_config, models=none, resource_type="model") %}
	{{ return(adapter.dispatch("fetch_configured_models", packages=dbt_meta_testing._get_meta_test_namespaces())(meta_config, models, resource_type)) }}
	{% endmacro %}