How to use the objection.RelationExpression.create function in objection

export default function eagerScope(modelClass, expr, scopes, filters = null,
  prepend = false, isRoot = true) {
  if (isRoot) {
    expr = expr?.isObjectionRelationExpression
      ? expr.clone()
      : RelationExpression.create(expr)
  } else {
    // Only add the scope if it's not already defined by the eager statement and
    // if it's actually available as a filter in the model's namedFilters list.
    for (const scope of scopes) {
      if (!expr.args.includes(scope) &&
          (modelClass.namedFilters[scope] || filters?.[scope])) {
        expr.args[prepend ? 'unshift' : 'push'](scope)
      }
    }
  }
  if (expr.numChildren > 0) {
    const relations = modelClass.getRelations()
    for (const child of Object.values(expr.children)) {
      const relation = relations[child.name]
      if (!relation) {
        throw new RelationError(

throw new errors.GeneralError('You must provide an Objection Model');
    }

    const whitelist = Object.values(OPERATORS).concat(options.whitelist || []);

    super(Object.assign({
      id: options.model.idColumn || 'id',
      whitelist
    }, options));

    this.idSeparator = options.idSeparator || ',';
    this.jsonSchema = options.model.jsonSchema;
    this.allowedEager = options.allowedEager && RelationExpression.create(options.allowedEager);
    this.namedEagerFilters = options.namedEagerFilters;
    this.eagerFilters = options.eagerFilters;
    this.allowedInsert = options.allowedInsert && RelationExpression.create(options.allowedInsert);
    this.insertGraphOptions = options.insertGraphOptions;
    this.createUseUpsertGraph = options.createUseUpsertGraph;
    this.allowedUpsert = options.allowedUpsert && RelationExpression.create(options.allowedUpsert);
    this.upsertGraphOptions = options.upsertGraphOptions;
  }

mergeRelations (optionRelations, paramRelations) {
    if (!paramRelations) {
      return optionRelations;
    }

    if (!optionRelations) {
      return RelationExpression.create(paramRelations);
    }

    return optionRelations.merge(paramRelations);
  }

const whitelist = Object.values(OPERATORS).concat(options.whitelist || []);

    super(Object.assign({
      id: options.model.idColumn || 'id',
      whitelist
    }, options));

    this.idSeparator = options.idSeparator || ',';
    this.jsonSchema = options.model.jsonSchema;
    this.allowedEager = options.allowedEager && RelationExpression.create(options.allowedEager);
    this.namedEagerFilters = options.namedEagerFilters;
    this.eagerFilters = options.eagerFilters;
    this.allowedInsert = options.allowedInsert && RelationExpression.create(options.allowedInsert);
    this.insertGraphOptions = options.insertGraphOptions;
    this.createUseUpsertGraph = options.createUseUpsertGraph;
    this.allowedUpsert = options.allowedUpsert && RelationExpression.create(options.allowedUpsert);
    this.upsertGraphOptions = options.upsertGraphOptions;
  }

constructor (options) {
    if (!options.model) {
      throw new errors.GeneralError('You must provide an Objection Model');
    }

    const whitelist = Object.values(OPERATORS).concat(options.whitelist || []);

    super(Object.assign({
      id: options.model.idColumn || 'id',
      whitelist
    }, options));

    this.idSeparator = options.idSeparator || ',';
    this.jsonSchema = options.model.jsonSchema;
    this.allowedEager = options.allowedEager && RelationExpression.create(options.allowedEager);
    this.namedEagerFilters = options.namedEagerFilters;
    this.eagerFilters = options.eagerFilters;
    this.allowedInsert = options.allowedInsert && RelationExpression.create(options.allowedInsert);
    this.insertGraphOptions = options.insertGraphOptions;
    this.createUseUpsertGraph = options.createUseUpsertGraph;
    this.allowedUpsert = options.allowedUpsert && RelationExpression.create(options.allowedUpsert);
    this.upsertGraphOptions = options.upsertGraphOptions;
  }

const DESERIALIZED_ARRAY_OPERATORS = [
  'between',
  'not between',
  '?|',
  '?&'
];

const NON_COMPARISON_OPERATORS = [
  '@>',
  '?',
  '<@',
  '?|',
  '?&'
];

const NO_RELATIONS = RelationExpression.create('[]');

/**
 * Class representing an feathers adapter for Objection.js ORM.
 * @param {object} options
 * @param {string} [options.id='id'] - database id field
 * @param {string} [options.idSeparator=','] - id field primary keys separator char
 * @param {object} options.model - an Objection model
 * @param {object} options.paginate
 * @param {object} options.events
 * @param {string} options.allowedEager - Objection eager loading string.
 */
class Service extends AdapterService {
  constructor (options) {
    if (!options.model) {
      throw new errors.GeneralError('You must provide an Objection Model');
    }