Validates Ecto.Changeset.foreign_key_constraint/3 annotations for Postgres FKs.

Examples

With a foreign key on orders.account_id, before:

def changeset(order, attrs) do
  order
  |> Ecto.Changeset.cast(attrs, [:account_id])
  |> Ecto.Changeset.validate_required([:account_id])
end

The database rejects missing accounts, but the caller may see a low-level constraint error instead of an :account_id changeset error.

After, annotate the changeset with the matching constraint:

def changeset(order, attrs) do
  order
  |> Ecto.Changeset.cast(attrs, [:account_id])
  |> Ecto.Changeset.validate_required([:account_id])
  |> Ecto.Changeset.foreign_key_constraint(:account_id)
end

Ecto can report the invalid relationship through the changeset API.

Notes

The check skips dynamic cast or change field lists and foreign keys whose columns cannot be mapped to Ecto schema fields.

Options

• :validate - explicit false disables this check.
• :paths - required non-empty list of source paths to parse for changeset functions.
• :otp_app - OTP app used for compiled schema discovery. When the target repo can report config()[:otp_app], this is inferred.
• :schema_modules - explicit non-empty list of schema modules to inspect instead of discovering schemas from :otp_app.
• :rules - optional rule keyword list or non-empty list of rule keyword lists. Rules use only shared scope keys.

This check requires :paths and schema discovery from the target repo's inferred :otp_app, explicit :otp_app, or explicit :schema_modules, so bare-module configuration is not valid.

Run globally for discovered schemas:

{Bylaw.Db.Adapters.Postgres.Checks.EctoChangesetForeignKeyConstraints,
 paths: ["lib/my_app"]}

Run globally for explicit schema modules:

{Bylaw.Db.Adapters.Postgres.Checks.EctoChangesetForeignKeyConstraints,
 paths: ["lib/my_app/billing"],
 schema_modules: [MyApp.Billing.Invoice, MyApp.Billing.Payment]}

Run only for matching rule scopes:

{Bylaw.Db.Adapters.Postgres.Checks.EctoChangesetForeignKeyConstraints,
 paths: ["lib/my_app"],
 rules: [where: [schemas: ["public"]], except: [[tables: ["events"], columns: ["actor_id"]]]]}

The check discovers compiled Ecto schemas through reflection, parses source files for conservative changeset candidates, and only requires foreign_key_constraint/3 when a candidate casts the local foreign-key field.

Usage

Add this module to the checks passed to Bylaw.Db.Adapters.Postgres.validate/2. See the README usage section for the full ExUnit setup.