Ember: Finding loaded associations

ember-check-associations.js

function hasMissingAssociations(record, associationName) {
    if (_.isArray(associationName)) {
      return _.some(associationName, name => {
        hasMissingAssociations(record, name);
      });
    }

    const relationship = record.relationshipFor(associationName);
    if (!relationship) {
      return false;
    }

    const associationModelName = relationship.type.replace(/-/g, '_');
    const idKey = _.camelCase(associationModelName) + (relationship.kind === "hasMany" ? 'Ids' : 'Id');
    const ids = _.flatten(record.get(idKey));
    return _.some(ids, (id) => {
      return !store.peekRecord(associationModelName, id);
    });
  }