Email Validation Strategy

We use EctoCommons.EmailValidator with both :html_input and :pow checks, defined centrally in Mv.Constants.email_validator_checks/0.

Checks Used

:html_input - Pragmatic validation matching browser <input type="email"> behavior
:pow - Stricter validation following email spec, supports internationalization (Unicode)

Rationale

Using both checks ensures:

Compatibility with common email providers (:html_input) - Matches what users expect from web forms
Compliance with email standards (:pow) - Follows RFC 5322 and related specifications
Support for international email addresses (:pow) - Allows Unicode characters in email addresses

This dual approach provides a balance between user experience (accepting common email formats) and technical correctness (validating against email standards).

Usage

The checks are used consistently across all email validation points:

Mv.Membership.Import.MemberCSV.validate_row/3 - CSV import validation
Mv.Membership.Member validations - Member resource validation
Mv.Accounts.User validations - User resource validation

All three locations use Mv.Constants.email_validator_checks() to ensure consistency.

Implementation Details

CSV Import Validation

The CSV import uses a schemaless changeset for email validation:

changeset =
  {%{}, %{email: :string}}
  |> Ecto.Changeset.cast(%{email: Map.get(member_attrs, :email)}, [:email])
  |> Ecto.Changeset.update_change(:email, &String.trim/1)
  |> Ecto.Changeset.validate_required([:email])
  |> EctoCommons.EmailValidator.validate_email(:email, checks: Mv.Constants.email_validator_checks())

This approach:

Trims whitespace before validation
Validates email is required
Validates email format using the centralized checks
Provides consistent error messages via Gettext

Resource Validations

Both Member and User resources use similar schemaless changesets within their Ash validations, ensuring consistent validation behavior across the application.

Changing the Validation Strategy

To change the email validation checks, update the @email_validator_checks constant in Mv.Constants. This will automatically apply to all validation points.

Note: Changing the validation strategy may affect existing data. Consider:

Whether existing emails will still be valid
Migration strategy for invalid emails
User communication if validation becomes stricter

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