AntD的 upload组件的使用
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13-React基础/09-AntD框架的upload组件上传图片时遇到的一些坑.md
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590
13-React基础/09-AntD框架的upload组件上传图片时遇到的一些坑.md
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## 前言
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本次做后台管理系统，采用的是 AntD 框架。涉及到图片的上传，用的是AntD的 [upload](https://ant.design/components/upload-cn/) 组件。
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前端做文件上传这个功能，是很有技术难度的。既然框架给我们提供好了，那就直接用呗。结果用的时候，发现 upload 组件的很多bug。
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## 使用 AntD 的 upload 组件做图片的上传
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因为需要上传多张图片，所以采用的是照片墙的形式。上传成功后的界面如下：
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按照官方提供的实例，特此整理出项目开发中的完整写法，亲测有效。代码如下：
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```javascript
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/* eslint-disable */
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import { Upload, Icon, Modal, Form } from 'antd';
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const FormItem = Form.Item;
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class PicturesWall extends PureComponent {
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state = {
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previewVisible: false,
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previewImage: '',
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imgList: [],
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};
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handleChange = ({ file, fileList }) => {
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console.log(JSON.stringify(file)); // file 是当前正在上传的 单个 img
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console.log(JSON.stringify(fileList)); // fileList 是已上传的全部 img 列表
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this.setState({
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imgList: fileList,
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});
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};
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handleCancel = () => this.setState({ previewVisible: false });
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handlePreview = file => {
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this.setState({
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previewImage: file.url || file.thumbUrl,
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previewVisible: true,
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});
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};
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// 参考链接：https://www.jianshu.com/p/f356f050b3c9
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handleBeforeUpload = file => {
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//限制图片 格式、size、分辨率
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const isJPG = file.type === 'image/jpeg';
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const isJPEG = file.type === 'image/jpeg';
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const isGIF = file.type === 'image/gif';
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const isPNG = file.type === 'image/png';
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if (!(isJPG || isJPEG || isGIF || isPNG)) {
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Modal.error({
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title: '只能上传JPG 、JPEG 、GIF、 PNG格式的图片~',
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});
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return;
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}
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const isLt2M = file.size / 1024 / 1024 < 2;
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if (!isLt2M) {
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Modal.error({
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title: '超过2M限制 不允许上传~',
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});
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return;
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}
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return (isJPG || isJPEG || isGIF || isPNG) && isLt2M && this.checkImageWH(file);
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};
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//返回一个 promise：检测通过则返回resolve；失败则返回reject，并阻止图片上传
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checkImageWH(file) {
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let self = this;
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return new Promise(function(resolve, reject) {
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let filereader = new FileReader();
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filereader.onload = e => {
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let src = e.target.result;
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const image = new Image();
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image.onload = function() {
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// 获取图片的宽高，并存放到file对象中
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console.log('file width :' + this.width);
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console.log('file height :' + this.height);
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file.width = this.width;
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file.height = this.height;
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resolve();
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};
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image.onerror = reject;
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image.src = src;
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};
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filereader.readAsDataURL(file);
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});
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}
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handleSubmit = e => {
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const { dispatch, form } = this.props;
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e.preventDefault();
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form.validateFieldsAndScroll((err, values) => {// values 是form表单里的参数
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// 点击按钮后，将表单提交给后台
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dispatch({
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type: 'mymodel/submitFormData',
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payload: values,
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});
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});
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};
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render() {
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const { previewVisible, previewImage, imgList } = this.state; // 从 state 中拿数据
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const uploadButton = (
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<div>
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<Icon type="plus" />
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<div className="ant-upload-text">Upload</div>
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</div>
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);
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return (
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<div className="clearfix">
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<Form onSubmit={this.handleSubmit} hideRequiredMark style={{ marginTop: 8 }}>
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<FormItem label="工厂图片" {...formItemLayout}>
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{getFieldDecorator('myImg')(
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<Upload
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action="//jsonplaceholder.typicode.com/posts/" // 这个是接口请求
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data={file => ({ // data里存放的是接口的请求参数
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param1: myParam1,
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param2: myParam2,
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photoCotent: file, // file 是当前正在上传的图片
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photoWidth: file.height, // 通过 handleBeforeUpload 获取 图片的宽高
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photoHeight: file.width,
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})}
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listType="picture-card"
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fileList={this.state.imgList}
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onPreview={this.handlePreview} // 点击图片缩略图，进行预览
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beforeUpload={this.handleBeforeUpload} // 上传之前，对图片的格式做校验，并获取图片的宽高
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onChange={this.handleChange} // 每次上传图片时，都会触发这个方法
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>
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{this.state.imgList.length >= 9 ? null : uploadButton}
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</Upload>
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)}
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</FormItem>
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</Form>
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<Modal visible={previewVisible} footer={null} onCancel={this.handleCancel}>
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<img alt="example" style={{ width: '100%' }} src={previewImage} />
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</Modal>
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</div>
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);
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}
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}
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export default PicturesWall;
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```
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## 上传后，点击图片预览，浏览器卡死的问题
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依据上方的代码，通过 Antd 的 upload 组件将图片上传成功后，点击图片的缩略图，理应可以在当前页面弹出 Modal，预览图片。但实际的结果是，浏览器一定会卡死。
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定位问题发现，原因竟然是：图片上传成功后， upload 会将其转为 base64编码。base64这个字符串太大了，点击图片预览的时候，浏览器在解析一大串字符串，然后就卡死了。详细过程描述如下。
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上方代码中，我们可以把 handleChange(file, fileList)方法中的 `file`、以及 `fileList`打印出来看看。 `file`指的是当前正在上传的 单个 img，`fileList`是已上传的全部 img 列表。 当我上传完 两张图片后， 打印结果如下：
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file的打印的结果如下：
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```json
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{
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"uid": "rc-upload-1551084269812-5",
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"width": 600,
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"height": 354,
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"lastModified": 1546701318000,
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"lastModifiedDate": "2019-01-05T15:15:18.000Z",
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"name": "e30e7b9680634b2c888c8bb513cc595d.jpg",
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"size": 31731,
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"type": "image/jpeg",
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"percent": 100,
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"originFileObj": {
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"uid": "rc-upload-1551084269812-5",
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"width": 600,
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"height": 354
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},
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"status": "done",
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"thumbUrl": "data:image/jpeg;base64,/9j/4AAQSkZJRgABAQAHQ9qKKlbimcXrIH9o2vH/AC2T+ddPj98v+9RRWsuhnHdk0ar9qb5R0Pb6VPB/qh9aKKiRr0Irnt/vUDr+NFFJCRqWxJik5Pb+dLJ938aKK06mYSdKKKKBH//Z",
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"response": {
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"retCode": 0,
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"imgUrl": "http://qianguyihao.com/opfewfwj098902kpkpkkj976fe.jpg",
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"photoid": 271850
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}
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}
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```
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fileList 的打印结果：
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```json
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[
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{
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"uid": "rc-upload-1551084269812-3",
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"width": 1000,
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"height": 667,
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"lastModified": 1501414799000,
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"lastModifiedDate": "2017-07-30T11:39:59.000Z",
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"name": "29381f30e924b89914e91b33.jpg",
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"size": 135204,
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"type": "image/jpeg",
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"percent": 100,
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"originFileObj": {
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"uid": "rc-upload-1551084269812-3",
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"width": 1000,
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"height": 667
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},
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"status": "done",
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"thumbUrl": "data:image/jpeg;base64,/E3ju1tlaK1fzJOnHQU3LsLV7HO6Zrk11MZJ7luT0A4FZuRagi9quvzQQ4iuEJ7ZpqTG4djDsPFl2Lg733f8C4q+YhQ8zoYfGSqoMmfwo5huLL0HjiyPDSYPvxRdC1XQvxeLrB8fvl/OnoLmL9vrdvvYS3NGFVe2YsASOh71JfQyrqV2mXLHOcccVSIYEnDyZO9XXB9KYH//Z",
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"response": {
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"retCode": 0,
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"msg": "success",
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"imgUrl": "http://qianguyihao.com/hfwpjouiurewnmbhepr689.jpg",
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}
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},
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{
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"uid": "rc-upload-1551084269812-5",
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"width": 600,
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"height": 354,
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"lastModified": 1546701318000,
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"lastModifiedDate": "2019-01-05T15:15:18.000Z",
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"name": "e30e7b9680634b2c888c8bb513cc595d.jpg",
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"size": 31731,
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"type": "image/jpeg",
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"percent": 100,
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"originFileObj": {
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"uid": "rc-upload-1551084269812-5",
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"width": 600,
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"height": 354
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},
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"status": "done",
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"thumbUrl": "data:image/jpeg;base64,/9j/4AAQSkZJRgABAQAHQ9qKKlbimcXrIH9o2vH/AC2T+ddPj98v+9RRWsuhnHdk0ar9qb5R0Pb6VPB/qh9aKKiRr0Irnt/vUDr+NFFJCRqWxJik5Pb+dLJ938aKK06mYSdKKKKBH//Z",
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"response": {
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"retCode": 0,
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"imgUrl": "http://qianguyihao.com/opfewfwj098902kpkpkkj976fe.jpg",
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"photoid": 271850
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}
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}
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]
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```
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上方的json数据中，需要做几点解释：
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（1）`response` 字段里面的数据，就是请求接口后，后台返回给前端的数据，里面包含了图片的url链接。
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（2）`status` 字段里存放的是图片上传的实时状态。
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（3）`thumbUrl`字段里面存放的是图片的base64编码。
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这个base64编码非常非常长。当点击图片预览的时候，其实就是加载的 thumbUrl 这个字段里的资源，难怪浏览器会卡死。
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**解决办法**：在 handleChange方法里，图片上传成功后，将 thumbUrl 字段里面的 base64 编码改为真实的图片url。代码实现如下：
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```javascript
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handleChange = ({ file, fileList }) => {
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console.log(JSON.stringify(file)); // file 是当前正在上传的 单个 img
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console.log(JSON.stringify(fileList)); // fileList 是已上传的全部 img 列表
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if (file && file.response && file.response.retCode == 0) {
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console.log('图片上传成功');
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fileList.forEach(item => {
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// 【重要】将 图片的base64替换为图片的url。 这一行一定不会能少。
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// 图片上传成功后，fileList数组中的 thumbUrl 中保存的是图片的base64字符串，这种情况，导致的问题是：图片上传成功后，点击图片缩略图，浏览器会会卡死。而下面这行代码，可以解决该bug。
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item.thumbUrl = item.response.imgUrl;
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});
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}
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this.setState({
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imgList: fileList,
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});
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};
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```
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## 新需求：编辑现有页面
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上面一段的代码中，我们是在新建的页面中，从零开始上传页面。
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现在有个新的需求：如何编辑现有的页面呢？也就是说说，现有的页面中，是默认有几张图片的。当我编辑这个页面时，可以对现有的图片做增删，也能增加新的图片。
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我的model层代码，是用 redux 写的。实现思路如下：
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（1）PicturesWall.js：
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```javascript
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/* eslint-disable */
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import { Upload, Icon, Modal, Form } from 'antd';
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const FormItem = Form.Item;
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class PicturesWall extends PureComponent {
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state = {
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previewVisible: false,
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previewImage: '',
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};
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// 页面初始化的时候，从接口拉取默认的图片数据
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componentDidMount() {
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const { dispatch } = this.props;
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dispatch({
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type: 'mymodel/getAllInfo',
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payload: { params: xxx },
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});
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}
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handleChange = ({ file, fileList }) => {
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const { dispatch } = this.props;
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if (file && file.response && file.response.retCode == 0) {
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console.log('图片上传成功');
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fileList.forEach(item => {
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// 【重要】将 图片的base64替换为图片的url。 这一行一定不会能少。
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// 图片上传成功后，fileList数组中的 thumbUrl 中保存的是图片的base64字符串，这种情况，导致的问题是：图片上传成功后，点击图片缩略图，浏览器会会卡死。而下面这行代码，可以解决该bug。
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item.thumbUrl = item.response.imgUrl;
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});
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}
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dispatch({
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type: 'mymodel/setImgList',
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payload: fileList,
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});
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};
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handleCancel = () => this.setState({ previewVisible: false });
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handlePreview = file => {
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this.setState({
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previewImage: file.url || file.thumbUrl,
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previewVisible: true,
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});
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};
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// 参考链接：https://www.jianshu.com/p/f356f050b3c9
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handleBeforeUpload = file => {
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//限制图片 格式、size、分辨率
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const isJPG = file.type === 'image/jpeg';
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const isJPEG = file.type === 'image/jpeg';
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const isGIF = file.type === 'image/gif';
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const isPNG = file.type === 'image/png';
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if (!(isJPG || isJPEG || isGIF || isPNG)) {
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Modal.error({
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title: '只能上传JPG 、JPEG 、GIF、 PNG格式的图片~',
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});
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return;
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}
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const isLt2M = file.size / 1024 / 1024 < 2;
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if (!isLt2M) {
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Modal.error({
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title: '超过2M限制 不允许上传~',
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});
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return;
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}
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return (isJPG || isJPEG || isGIF || isPNG) && isLt2M && this.checkImageWH(file);
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};
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//返回一个 promise：检测通过则返回resolve；失败则返回reject，并阻止图片上传
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checkImageWH(file) {
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let self = this;
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return new Promise(function(resolve, reject) {
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let filereader = new FileReader();
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filereader.onload = e => {
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let src = e.target.result;
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const image = new Image();
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image.onload = function() {
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// 获取图片的宽高，并存放到file对象中
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console.log('file width :' + this.width);
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console.log('file height :' + this.height);
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file.width = this.width;
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file.height = this.height;
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resolve();
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};
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image.onerror = reject;
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image.src = src;
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};
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filereader.readAsDataURL(file);
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});
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}
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handleSubmit = e => {
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const { dispatch, form } = this.props;
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e.preventDefault();
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form.validateFieldsAndScroll((err, values) => {
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// values 是form表单里的参数
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// 点击按钮后，将表单提交给后台
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dispatch({
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type: 'mymodel/submitFormData',
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payload: values,
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});
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});
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};
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render() {
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const { previewVisible, previewImage } = this.state; // 从 state 中拿数据
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const {
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mymodel: { imgList }, // 从props中拿到的图片数据
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} = this.props;
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const uploadButton = (
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<div>
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<Icon type="plus" />
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<div className="ant-upload-text">Upload</div>
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</div>
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);
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return (
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<div className="clearfix">
|
||||
<Form onSubmit={this.handleSubmit} hideRequiredMark style={{ marginTop: 8 }}>
|
||||
<FormItem label="工厂图片" {...formItemLayout}>
|
||||
{getFieldDecorator('myImg')(
|
||||
<Upload
|
||||
action="//jsonplaceholder.typicode.com/posts/" // 这个是接口请求
|
||||
data={file => ({
|
||||
// data里存放的是接口的请求参数
|
||||
param1: myParam1,
|
||||
param2: myParam2,
|
||||
photoCotent: file, // file 是当前正在上传的图片
|
||||
photoWidth: file.height, // 通过 handleBeforeUpload 获取 图片的宽高
|
||||
photoHeight: file.width,
|
||||
})}
|
||||
listType="picture-card"
|
||||
fileList={imgList} // 改为从 props 里拿图片数据，而不是从 state
|
||||
onPreview={this.handlePreview} // 点击图片缩略图，进行预览
|
||||
beforeUpload={this.handleBeforeUpload} // 上传之前，对图片的格式做校验，并获取图片的宽高
|
||||
onChange={this.handleChange} // 每次上传图片时，都会触发这个方法
|
||||
>
|
||||
{this.state.imgList.length >= 9 ? null : uploadButton}
|
||||
</Upload>
|
||||
)}
|
||||
</FormItem>
|
||||
</Form>
|
||||
<Modal visible={previewVisible} footer={null} onCancel={this.handleCancel}>
|
||||
<img alt="example" style={{ width: '100%' }} src={previewImage} />
|
||||
</Modal>
|
||||
</div>
|
||||
);
|
||||
}
|
||||
}
|
||||
|
||||
export default PicturesWall;
|
||||
|
||||
```
|
||||
|
||||
（2）mymodel.js:
|
||||
|
||||
```javascript
|
||||
/* eslint-disable */
|
||||
|
||||
import { routerRedux } from 'dva/router';
|
||||
import { message, Modal } from 'antd';
|
||||
import {
|
||||
getTuanList,
|
||||
getAllFactory,
|
||||
getAllFactGoods,
|
||||
createFactShop,
|
||||
updateFactShop,
|
||||
deleteFactShop,
|
||||
updateFactGoodsStatus,
|
||||
queryShopDetail,
|
||||
createFactGoods,
|
||||
} from '../services/api';
|
||||
import { trim, getCookie } from '../utils/utils';
|
||||
|
||||
export default {
|
||||
namespace: 'factory',
|
||||
|
||||
state: {
|
||||
form: {},
|
||||
list: [],
|
||||
listDetail: [],
|
||||
goodsList: [],
|
||||
goodsListDetail: [],
|
||||
pagination: {
|
||||
pageSize: 10,
|
||||
total: 0,
|
||||
current: 1,
|
||||
},
|
||||
imgList: [], //图片
|
||||
},
|
||||
subscriptions: {
|
||||
setup({ dispatch, history }) {
|
||||
history.listen(location => {
|
||||
if (location.pathname !== '/xx/xxx') return;
|
||||
if (!location.state || !location.state.xxxId) return;
|
||||
dispatch({
|
||||
type: 'fetch',
|
||||
payload: location.state,
|
||||
});
|
||||
});
|
||||
},
|
||||
},
|
||||
|
||||
effects: {
|
||||
// 接口。获取所有工厂店的列表 (步骤02)
|
||||
*getAllInfo({ payload }, { select, call, put }) {
|
||||
yield put({
|
||||
type: 'form',
|
||||
payload,
|
||||
});
|
||||
console.log('params:' + JSON.stringify(payload));
|
||||
|
||||
let params = {};
|
||||
params = payload;
|
||||
|
||||
const response = yield call(getAllFactory, params);
|
||||
|
||||
console.log('smyhvae response:' + JSON.stringify(response));
|
||||
if (response.error) return;
|
||||
yield put({
|
||||
type: 'allInfo',
|
||||
payload:
|
||||
(response.data &&
|
||||
response.data.map(item => ({
|
||||
xx1: item.yy1,
|
||||
xx2: item.yy2,
|
||||
}))) ||
|
||||
[],
|
||||
});
|
||||
|
||||
// response 里包含了接口返回给前端的默认图片数据
|
||||
if (response && response.data && response.data[0] && response.data[0].my_jpg) {
|
||||
let tempImgList = response.data[0].my_jpg.split(',');
|
||||
let imgList = [];
|
||||
|
||||
if (tempImgList.length > 0) {
|
||||
tempImgList.forEach(item => {
|
||||
imgList.push({
|
||||
uid: item,
|
||||
name: 'xxx.png',
|
||||
status: 'done',
|
||||
thumbUrl: item,
|
||||
});
|
||||
});
|
||||
}
|
||||
|
||||
// 通过 redux的方式 将 默认图片 传给 imgList
|
||||
console.log('smyhvae payload imgList:' + JSON.stringify(imgList));
|
||||
yield put({
|
||||
type: 'setImgList',
|
||||
payload: imgList,
|
||||
});
|
||||
}
|
||||
},
|
||||
|
||||
*setImgList({ payload }, { call, put }) {
|
||||
console.log('smyhvae model setImgList');
|
||||
yield put({
|
||||
type: 'getImgList',
|
||||
payload,
|
||||
});
|
||||
},
|
||||
},
|
||||
|
||||
reducers: {
|
||||
allInfo(state, action) {
|
||||
return {
|
||||
...state,
|
||||
list: action.payload,
|
||||
};
|
||||
},
|
||||
getImgList(state, action) {
|
||||
return {
|
||||
...state,
|
||||
imgList: action.payload,
|
||||
};
|
||||
},
|
||||
},
|
||||
};
|
||||
|
||||
```
|
||||
|
||||
大功告成。
|
||||
|
||||
|
||||
本文感谢 ld 同学的支持。
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
Loading…
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Reference in New Issue
Block a user