ngxs-state-decorator.ts

const META_KEY = 'NGXS_META';

function State(options) {
  return (target) => {
    const meta = ensureStoreMetadata(target);
    // Handle inheritance
    if (Object.getPrototypeOf(target).hasOwnProperty(META_KEY)) {
      const parentMeta = Object.getPrototypeOf(target)[META_KEY];
      meta.actions = Object.assign({}, meta.actions, parentMeta.actions);
    }
    meta.children = options.children;
    meta.defaults = options.defaults;
    meta.name = options.name;
    if (!options.name) {
      throw new Error(`States must register a 'name' property`);
    }
    if (!stateNameRegex.test(options.name)) {
      throw new Error(stateNameErrorMessage(options.name));
    }
  };
}

@State({
  name: 'todos',
  defaults: []
})
class TodosState {}