Егор Кротенко Егор Кротенко -4 years ago 185
Javascript Question

this.setState is not a function ( trying Upload Image) ReactJs

Try create upload function with cropper component. But when I try set state it says that


Uncaught TypeError: this.setState is not a function at FileReader.reader.onload


Component

import React, { Component, PropTypes } from 'react'
import { Link, browserHistory } from 'react-router'
import { connect } from 'react-redux'
import Cropper from 'react-cropper';

class HeadPortrait extends Component {
constructor(props) {
super(props)
this.state = {
image: '',
}
}

clickadd(e) {
document.getElementById('uploadfiles').click();
}

loadFile(e) {
e.preventDefault();
var reader = new FileReader();
reader.onload = function () {
this.setState({ image: reader.result })
};
reader.readAsDataURL(e.target.files[0]);
;
};

_crop() {
// image in dataUrl
console.log(this.refs.cropper.getCroppedCanvas().toDataURL());
}

render() {
return (
<div className="group-content width415">
<input id="uploadfiles" type="file" accept="image/*" onChange={this.loadFile.bind(this)}></input>
<a onClick={this.clickadd.bind(this)} className="gt-btn-small gt-left ">Add Image</a>
<div>
<div className="bigImageprev gt-left"><img width="300" height="300" id="output" /></div>
</div>
<div className="gt-clear"></div>
<div className="btnSaveImage gt-right"><a className="gt-btn-small" href="#">Save</a></div>

<Cropper
ref='cropper'
src={this.state.image}
style={{ height: 400, width: '100%' }}
// Cropper.js options
aspectRatio={16 / 9}
guides={false}
crop={this._crop.bind(this)} />
</div>
)
}
}

function mapStateToProps(state) {
return {
// stories: state.stories
}
}

export default connect(mapStateToProps)(HeadPortrait)


Trying do like in example https://github.com/roadmanfong/react-cropper/blob/master/example/src/Demo.jsx

Answer Source

Problem is the function you are using for onload: this there is not your classes this. Try either an arrow function:

reader.onload = () => this.setState({ image: reader.result })

Or assign this to a variable before

const scope = this
reader.onload = function () {
  scope.setState({ image: reader.result })
}

Also it is worth binding the event handlers in the constructor rather than directly in render, because this way you'll re-render your component no matter how your state changes - since the event handler is a new reference each time:

constructor(props) {
  super(props)
  this.state = {
    image: '',
  } 
  this.onload = this.onload.bind(this) // properly bound once
}

In render:

<input onChange={this.loadFile}></input>
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