[Constraints] Render 'to' and 'to_columns' fields on foreign key constraints

[MichelleArk]

Housekeeping

• I am a maintainer of dbt-adapters

Short description

As part of dbt-labs/dbt-core#8062. we are parsing and compiling new to and to_columns fields on ModelLevelConstraint and ColumnLevelConstraint. dbt-adapters should use these new fields, when populated, to render out the foreign key constraint instead of expression. expression support should remain as-is for backward-compatability.

Context

No response

Acceptance criteria

Tasks

Beta Give feedback

1. Use to and to_column fields to render foreign key constraints on model-level and column-level constraints
2. maintain expression support for backward compatability

Testing

Tasks

Beta Give feedback

1. new integration test for to and to_columns usage as this will be the recommended practice
2. ensure existing test coverage (e.g. unit testing) exists for expression support

Security

N/A

Docs

dbt-labs/dbt-core#10414 (comment)

Consequences

This will update the base implementation of constraint rendering in a backward-compatible manner. Other adapters will be able to extend it as necessary to support to and to_columns, but will continue to be able to use the default implementation.

[FishtownBuildBot]

Opened a new issue in dbt-labs/docs.getdbt.com: dbt-labs/docs.getdbt.com#5845