@rjsf/utils/src/canExpand.ts

Utility functions for @rjsf/core

import { FormContextType, RJSFSchema, StrictRJSFSchema, UiSchema } from './types';
import getUiOptions from './getUiOptions';

/** Checks whether the field described by `schema`, having the `uiSchema` and `formData` supports expanding. The UI for
 * the field can expand if it has additional properties, is not forced as non-expandable by the `uiSchema` and the
 * `formData` object doesn't already have `schema.maxProperties` elements.
 *
 * @param schema - The schema for the field that is being checked
 * @param [uiSchema={}] - The uiSchema for the field
 * @param [formData] - The formData for the field
 * @returns - True if the schema element has additionalProperties, is expandable, and not at the maxProperties limit
 */
export default function canExpand<T = any, S extends StrictRJSFSchema = RJSFSchema, F extends FormContextType = any>(
  schema: RJSFSchema,
  uiSchema: UiSchema<T, S, F> = {},
  formData?: T,
) {
  if (!(schema.additionalProperties || schema.patternProperties)) {
    return false;
  }
  const { expandable = true } = getUiOptions<T, S, F>(uiSchema);
  if (expandable === false) {
    return expandable;
  }
  // if ui:options.expandable was not explicitly set to false, we can add
  // another property if we have not exceeded maxProperties yet
  if (schema.maxProperties !== undefined && formData) {
    return Object.keys(formData).length < schema.maxProperties;
  }
  return true;
}