Card Field Components

Detailed reference for individual card and billing address field composables

Primer Checkout Android SDK is currently in beta (v3.0.0-beta.4). The API is subject to change before the stable release.

Each CardFormDefaults field component handles its own formatting, validation, keyboard configuration, and error display. All fields accept controller: PrimerCardFormController and modifier: Modifier = Modifier.

Card detail fields

CardNumberField

Aspect	Detail
Auto-formatting	Groups digits with spaces (e.g., 4242 4242 4242 4242)
Max length	16-19 digits depending on detected network
Keyboard type	KeyboardType.Number
Validation	Luhn algorithm check, minimum length per network
Validation timing	On blur (when user taps another field)
Trailing icon	Detected card network logo(s) (Visa, Mastercard, Amex, etc.)
Network detection	Local detection begins after the 1st digit; remote detection begins after the 8th digit

Supported networks: Visa, Mastercard, Amex, Diners Club, Discover, JCB, UnionPay, Maestro, Elo, Mir, Hiper, Hipercard, Cartes Bancaires, Dankort, Eftpos, Other.

ExpiryField

Aspect	Detail
Auto-formatting	Inserts / automatically (typing 1225 → 12/25)
Max length	5 characters (MM/YY)
Keyboard	KeyboardType.Number
Validation	Valid month (01–12), future date

CvvField

Aspect	Detail
Max length	4 digits for Amex, 3 for other networks
Keyboard	KeyboardType.Number
Visual	Password masking (dots)
Dynamic	Max length updates when card network is detected

CardholderField

Aspect	Detail
Keyboard	KeyboardType.Text with KeyboardCapitalization.Words
Validation	Required (non-empty) when session requires cardholder name
Visibility	Only rendered when CARDHOLDER_NAME is in state.cardFields

CardNetworkField

Aspect	Detail
Visibility	Only rendered when card has multiple networks (co-badged)
Interaction	Tapping a chip calls controller.selectCardNetwork(network)
No modifier parameter	Unlike other fields

Billing address fields

All billing fields are rendered only when required by session configuration.

Field	Keyboard	Validation	Notes
CountryCodeField	—	Required	Read-only; opens picker via requestCountrySelection()
FirstNameField	Text + Words capitalization	Required	—
LastNameField	Text + Words capitalization	Required	—
AddressLine1Field	Text	Required	—
AddressLine2Field	Text	Optional	—
CityField	Text	Required	—
StateField	Text	Required	Label adapts to selected country
PostalCodeField	Text	Required, format varies by country	Label adapts to selected country

Validation behavior

1. While typing — no error messages shown. isFormValid updates in real-time.
2. On blur — field is validated and any error is added to state.fieldErrors.
3. Error display — inline error text below the field using theme error color.
4. Error clearing — errors clear when corrected and re-validated on next blur.