React-Dropzone图片预览未显示 [英] React-Dropzone image preview not showing

问题描述

使用react-dropzone（ https://www.npmjs.com/package/react-dropzone ），并将文件记录到控制台，但无法获取状态更改时填充的图像预览。知道我在做什么错吗？

Using react-dropzone (https://www.npmjs.com/package/react-dropzone) and getting files logging to the console, but can't get image preview to populate on state change. Any idea what I'm doing wrong?

export default class JoinForm extends Component {
    constructor(props) {
    super(props)
        this.state = {
            imageFiles: []
    }
}

onDrop(imageFiles) {
    this.setState({
        imageFiles: imageFiles
    })
    console.log(imageFiles)  
}

render() {

    return(
        <form className='join-form' ref='joinForm' autoComplete='off'>
            <Dropzone
                onDrop={this.onDrop}
                className='dropzone'
                activeClassName='active-dropzone'
                multiple={false}>
      <div>Drag and drop or click to select a 550x550px file to upload.</div>
    </Dropzone>

            {this.state.imageFiles.length > 0 ? <div>
    <h2>Uploading {this.state.imageFiles.length} files...</h2>
    <div>{this.state.imageFiles.map((file) => <img src={file.preview} /> )}</div>
    </div> : null}
        </form>
    )
}

};

推荐答案

正确的答案：是个假人，忘了绑定它。

Correct answer to this: being a dummy and forgot to bind this.

<Dropzone
  onDrop={this.onDrop.bind(this)} //<= Here
  className='dropzone'
  activeClassName='active-dropzone'
  multiple={false}
  style={imageUploadStyle}>
    <div>Drag and drop or click to select a 550x550px file to upload.</div>
</Dropzone>

https://toddmotto.com/react-create-class-versus-component/

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