在mobx商店中未定义数组长度

Question

我试图从Redux转移到Mobx并尝试在mobx商店中设置一个数组，我使用装饰器来设置值。我能够从商店返回静态值，但下面的数组长度总是抛出和未定义的值。不确定以下代码有什么问题。有什么建议 ？

import {observable, action, computed} from 'mobx';

class FormDataStore {

    @observable formdata = [1,2,3];

    @action updateFormData = (formdata) => {
        this.formdata.push(formdata);
    }

    @computed get readdata() {
        return this.formdata.length;
    }

}

const store = new FormDataStore();
export default store

错误

FormDataStore.js:12 Uncaught TypeError: Cannot read property 'length' of undefined
    at FormDataStore.get (FormDataStore.js:12)
    at trackDerivedFunction$$1 (mobx.module.js:1142)
    at ComputedValue$$1.computeValue (mobx.module.js:934)
    at ComputedValue$$1.trackAndCompute (mobx.module.js:919)
    at ComputedValue$$1.get (mobx.module.js:879)
    at ObservableObjectAdministration$$1.read (mobx.module.js:3822)
    at FormDataStore.get (mobx.module.js:4086)
    at FormDataStore.get (mobx.module.js:295)
    at PreviewWindow.render (PreviewWindow.js:24)
    at Object.allowStateChanges$$1 (mobx.module.js:653)

以下是我尝试读取数据的方法

import React from "react";
import { Container } from "semantic-ui-react";
import Highlight from "react-highlight";
import {inject,observer} from 'mobx-react';

@inject('FormDataStore')


@observer
class PreviewWindow extends React.Component {



  render() {


    const {FormDataStore} = this.props;
    console.log(FormDataStore)

    return (
      <Container>
        <h1>JSon Preview</h1>
      <h1>{FormDataStore.getFormData}</h1>
          <Highlight language="javascript">{FormDataStore.readdata}</Highlight>

      </Container>
    );
  }
}

export default PreviewWindow;

Answer 1

.babelrc插件的顺序很重要，必须改变babel配置中插件的顺序来解决问题。

/// WRONG

"plugins": [
  "transform-class-properties",
  "transform-decorators-legacy"
]

// RIGHT

"plugins": [
  "transform-decorators-legacy",
  "transform-class-properties"
]