How to return values from data.custom to Select formio (typescript)?

Question

An error occured within custom function for country ReferenceError: getAddressResource is not defined from the code below. I don't know what I'm doing wrong?.

export default class Component extends (ParentCompoenent as any){

addResource = [];


getAddressResource() {
  return async function a(){
    try{
      
      const Provider = Formio.Providers.getProvider('storage', this.component.storage);
      if (Provider) {
          const provider = new Provider(this);
          let test =  await provider.getResources();
        return test;
      }
    } catch(e){

    }
  }
  }


static schema (...extend){
    return ParentCompoenent.schema({
      label: DISPLAY,
      type: ID,
      key: ID,
      clearOnHide: true,
      tableView: true,
      persistent: true,
      autoAdjust: true,
      hideLabel: true,
      storage: 'resources',
      columns: [
        { components: [ {
          label:'Country',
          key: 'country',
          type: 'select',
          input: true,
          dataSrc: 'custom',
    validate: {
      required: true
    },
    data: {
      custom:'getAddressResource()'
    }
        }], width: 4, offset: 0, push: 0, pull: 0, size: 'md' },