EXTERNAL_DATA

Injection token for external data signals.

External data provides a way to inject application state into form expressions. Each property in the record is a Signal that gets unwrapped and made available in the EvaluationContext under externalData.

Like DEFAULT_PROPS, this token is provided ONCE at the DynamicForm level and inherited by all children via Angular's hierarchical injector.

The token provides a Signal containing the external data record, which itself contains Signals. This allows the form to react to changes in which external data is available (outer Signal) and to changes in the external data values (inner Signals).

Presentation

const EXTERNAL_DATA: InjectionToken<
  Signal<Record<string, Signal<unknown>> | undefined>
>;

// In FieldContextRegistryService
const externalDataSignal = inject(EXTERNAL_DATA, { optional: true });

// When creating evaluation context:
const externalDataRecord = externalDataSignal?.();
const resolvedExternalData = externalDataRecord
  ? Object.fromEntries(
      Object.entries(externalDataRecord).map(([k, v]) => [k, v()])
    )
  : {};