Integration: Commerce Price module

Problem/Motivation

CRM Membership tracks membership information (membership types, memberships, and
membership periods) but has no way to track monetary amounts for payments such as
dues, fees, or renewals. To support payment tracking and future integration with
Commerce orders or payment gateways, we need a consistent, currency-aware way to
store and display prices.

Using custom decimal/currency fields would duplicate logic and diverge from
Drupal ecosystem standards. The Commerce module’s Price system provides a
battle-tested value object (number + currency code), rounding per currency, and
reuse across product pricing, orders, and payments.

Steps to reproduce

• N/A — this is a feature request.

Proposed resolution

Integrate the Commerce Price module
(commerce_price) so that membership-related amounts use the
Commerce Price field type and value object.

• Dependency: Add commerce:commerce_price as
  an optional dependency in crm_membership.info.yml so the module
  can run without Commerce when price features are not needed; or a required
  dependency if the project always wants price support.
• Field type: Use the commerce_price field
  type (PriceItem) for any field that stores a monetary amount (e.g. dues,
  fee, amount paid).
• Value handling: Use the
  \Drupal\commerce_price\Plugin\Field\FieldType\PriceItem and
  \Drupal\commerce_price\Price value object (number as string +
  currency code) for calculations and display; use
  commerce_price.rounder when rounding is required.
• Placement of price fields:
  • Membership type (config): Optionally add a config
    schema and stored config for a “default dues price” (amount + currency)
    per membership type, so renewal forms or order creation can default
    amounts. Config entities cannot have full Field API fields, so this would
    be stored as structured config (e.g. default_dues_amount,
    default_dues_currency) or via a dedicated config schema
    matching Commerce Price structure.
  • Membership period (content): Add a base field (or
    optional configurable field) of type commerce_price to store
    the amount paid or charged for that period (e.g. dues for that period).
    This allows reporting and display per period and aligns with
    Commerce/order data if we later link orders to periods.
• API: Provide getter/setter helpers on the relevant
  entities that return/accept Price objects where a price is
  stored, and document that callers should depend on
  commerce_price when using those APIs.

Remaining tasks

• Add commerce_price dependency (optional or required) to
  crm_membership.info.yml.
• Add Commerce Price base field(s) to the appropriate entity(ies)
  (e.g. crm_membership_period for “amount” or “dues”).
• If supporting default dues on membership types, add config schema and
  storage for price (amount + currency) on crm_membership_type.
• Update entity forms to display and validate Commerce Price field(s)
  (using Commerce’s form elements/widgets where applicable).
• Expose price in views (Views integration for Commerce Price if needed).
• Add/update tests for price storage, rounding, and display.
• Document the new dependency and any configuration in the module’s
  README or docs.

User interface changes

• Membership period add/edit forms: show a price field (amount + currency)
  for the period’s dues or amount paid, using Commerce Price widget/format.
• Optional: membership type form shows a “default dues” price used when
  creating or renewing periods.
• List and view displays for membership periods (and optionally membership
  types) show the price in the configured currency format.

API changes

• New or updated entity methods that work with
  \Drupal\commerce_price\Price (e.g.
  MembershipPeriod::getPrice() / setPrice(Price $price)).
• Services that need to round or calculate totals should type-hint and use
  commerce_price.rounder and the Price value object.
• Document dependency on commerce_price for code paths that
  use price fields or Price objects.

Data model changes

• Content entities (e.g. crm_membership_period):
  New base field of type commerce_price (e.g. price
  or dues) storing number and currency code via Commerce Price
  storage.
• Config entities (e.g. crm_membership_type):
  If default dues are supported, extend config export and schema with
  price-related keys (amount + currency) compatible with Commerce Price
  semantics; no new database tables from Commerce, only new columns or config
  keys.
• No change to existing membership or membership type keys; additive only.