Changes to dispatch in dbt v0.20

[jtcohen6]

Hey Claus! Planning to open this same issue in the dbt-date package momentarily :)

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.

In practice, this just looks like switching each macro like:

dbt-expectations/macros/math/log_natural.sql

Lines 1 to 3 in 730d195

	{% macro log_natural(x) -%}
	{{ adapter.dispatch('log_natural', packages=dbt_expectations._get_namespaces()) (x) }}
	{% endmacro %}

To:

{% macro log_natural(x) -%}
    {{ adapter.dispatch('log_natural', 'dbt_expectations') (x) }}
{% endmacro %}

I hope this could be as simple as Find + Replace for packages=dbt_expectations._get_namespaces() → 'dbt_expectations'.

For the README

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

dispatch:
  - macro_namespace: dbt_expectations
    search_order: ['my_project', 'dbt_expectations']  # enable override
  - macro_namespace: dbt_utils
    search_order: ['spark_utils', 'dbt_utils']  # shim for spark

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. 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).

See also:

• Rework adapter.dispatch(), remove packages arg dbt-labs/dbt-core#3383
• https://next.docs.getdbt.com/reference/dbt-jinja-functions/dispatch

[clausherther]

Hi @jtcohen6, thanks for much for this and the issue in dbt-date and the helpful comments on #61, really appreciate it! It'll take a bit to work through this and plan the 0.19.2/0.20.0 compatible releases, I'll let you know if I have any questions. Thanks again!