Question

我是MST的新手，很难找到更多有关异步操作的示例。我有一个api，它将根据您传递给它的参数返回不同的数据。在这种情况下，api可以返回照片或教程的数组。我已经为商店设置了初始值，如下所示：

data: {
   photos: [],
   tutorials: []
}

当前，我正在使用applySnapshot更新商店，最终，这将触发我的React组件的重新渲染。为了同时显示照片和教程，我需要两次调用api（有照片的参数，有第二次的教程）。我遇到一个问题，即第一次更新的快照显示照片和教程具有相同的值，并且仅在第二次更新时，我才能获得正确的值。我可能滥用applySnapshot来重新渲染我的React组件。我想知道更好/更合适的方法。在api产生响应后，重新渲染React组件的最佳方法是什么。任何建议都非常感谢

我已经这样开设了商店：

import { RootModel } from '.';
import { onSnapshot, getSnapshot, applySnapshot } from 'mobx-state-tree';

export const setupRootStore = () => {
  const rootTree = RootModel.create({
    data: {
      photos: [],
      tutorials: []
    }
  });
  // on snapshot listener
  onSnapshot(rootTree, snapshot => console.log('snapshot: ', snapshot));

  return { rootTree };
};

我使用生成器通过异步操作创建了以下模型：

import {types,Instance,applySnapshot,flow,onSnapshot} from 'mobx-state-tree';

const TestModel = types
  .model('Test', {
    photos: types.array(Results),
    tutorials: types.array(Results)
  })
  .actions(self => ({
    fetchData: flow(function* fetchData(param) {

      const results = yield api.fetch(param);

      applySnapshot(self, {
        ...self,
        photos: [... results, ...self.photos],
        tutorials: [... results, ...self.tutorials]
      });
    })
  }))
  .views(self => ({
    getPhoto() {
      return self.photos;
    },
    getTutorials() {
      return self.tutorials;
    }
  }));

const RootModel = types.model('Root', {
  data: TestModel
});

export { RootModel };

export type Root = Instance<typeof RootModel>;
export type Test = Instance<typeof TestModel>;

Photos.tsx的反应成分

import React, { Component } from 'react';
import Spinner from 'components/Spinner';
import { Root } from '../../stores';
import { observer, inject } from 'mobx-react';

interface Props {
  rootTree?: Root
}

@inject('rootTree')
@observer
class Photos extends Component<Props> {

  componentDidMount() {
      const { rootTree } = this.props;
      if (!rootTree) return null;
      rootTree.data.fetchData('photo');
  }

  componentDidUpdate(prevProps) {
    if (prevProps.ctx !== this.props.ctx) {
      const { rootTree } = this.props;
      if (!rootTree) return null;
      rootTree.data.fetchData('photo');
    }
  }

  displayPhoto() {
    const { rootTree } = this.props;
    if (!rootTree) return null;
    // calling method in MST view
    const photoResults = rootTree.data.getPhoto();

    if (photoResults.$treenode.snapshot[0]) {
      return (
        <div>
          <div className='photo-title'>{'Photo'}</div>
          {photoResults.$treenode.snapshot.map(Item => (
            <a href={photoItem.attributes.openUrl} target='_blank'>
              <img src={photoItem.url} />
            </a>
          ))}
        </div>
      );
    } else {
      return <Spinner />;
    }
  }

  render() {
    return <div className='photo-module'>{this.displayPhoto()}</div>;
  }
}

export default Photos;

类似地，Tutorials.tsx也是如此：

import React, { Component } from 'react';
import Spinner from '';
import { Root } from '../../stores';
import { observer, inject } from 'mobx-react';

interface Props {
  rootTree?: Root;
}

@inject('rootTree')
@observer
class Tutorials extends Component<Props> {

  componentDidMount() {
    if (this.props.ctx) {
      const { rootTree } = this.props;
      if (!rootTree) return null;
      rootTree.data.fetchData('tuts');
    }
  }

  componentDidUpdate(prevProps) {
    if (prevProps.ctx !== this.props.ctx) {
      const { rootTree } = this.props;
      if (!rootTree) return null;
      rootTree.search.fetchData('tuts');
    }
  }

  displayTutorials() {
    const { rootTree } = this.props;
    if (!rootTree) return null;
    // calling method in MST view
    const tutResults = rootTree.data.getTutorials();

    if (tutResults.$treenode.snapshot[0]) {
      return (
        <div>
          <div className='tutorials-title'>{'Tutorials'}</div>
          {tutResults.$treenode.snapshot.map(tutorialItem => (
            <a href={tutorialItem.attributes.openUrl} target='_blank'>
              <img src={tutorialItem.url} />
            </a>
          ))}
        </div>
      );
    } else {
      return <Spinner />;
    }
  }

  render() {
    return <div className='tutorials-module'>{this.displayTutorials()}</div>;
  }
}

export default Tutorials;

Answer 1

在这种情况下，为什么要使用applySnapshot？我认为没有必要。只需在操作中根据需要分配数据即可：

.actions(self => ({
     //If you're fetching both at the same time
    fetchData: flow(function* fetchData(param) {

      const results = yield api.fetch(param);

      //you need cast() if using Typescript otherwise I think it's optional
      self.photos = cast([...results.photos, ...self.photos])
      //do you really intend to prepend the results to the existing array or do you want to overwrite it with the sever response?
      self.tutorials = cast(results.tutorials)

    })
  }))

或者，如果您需要提出两个单独的请求来提取数据，则最好将其设为两个不同的操作

.actions(self => ({
    fetchPhotos: flow(function* fetchPhotos(param) {
      const results = yield api.fetch(param)
      self.photos = cast([... results, ...self.photos])      
    }),
    fetchTutorials: flow(function* fetchTutorials(param) {
      const results = yield api.fetch(param)
      self.tutorials = cast([... results, ...self.tutorials])      
    }),
  }))

无论如何，似乎您不需要applySnapshot。只需根据需要在操作中分配数据即可。在异步操作中分配数据没有什么特别的。

MobX状态树异步操作并重新渲染React组件

1 个答案: