How to reset ReactJS file input

Question

I have file upload input:

And I handle upload t

Answer 1

This work for me - ref={ref => this.fileInput = ref}

<input id="file_input_file" type="file" onChange={(e) => this._handleFileChange(e)} ref={ref=> this.fileInput = ref} />

then in my case once the file was uploaded to the server , I clear it by using the statement below

 this.fileInput.value = "";

Answer 2

What worked for me was setting a key attribute to the file input, then when I needed to reset it I update the key attribute value:

functionThatResetsTheFileInput() {
  let randomString = Math.random().toString(36);

  this.setState({
    theInputKey: randomString
  });
}

render() {
  return(
    <div>
      <input type="file"
             key={this.state.theInputKey || '' } />
      <button onClick={this.functionThatResetsTheFileInput()} />
    </div>
  )
}

That forces React to render the input again from scratch.

Answer 3

With every click onClick you can reset the input, so that even with the same file onChange will be triggered.

<input onChange={this.onChange} onClick={e => (e.target.value = null)} type="file" />

Answer 4

The following worked for me using React Hooks. This is done using what is known as a "controlled input". That means, the inputs are controlled by state, or their source of truth is state.

TL;DR Resetting the file input was a two-step process using both the useState() and useRef() hooks.

NOTE: I also included how I reset a text input in case anyone else was curious.

function CreatePost({ user }) {
    const [content, setContent] = React.useState("");
    const [image, setImage] = React.useState(null); //See Supporting Documentation #1
    const imageInputRef = React.useRef(); //See Supporting Documentation #2

    function handleSubmit(event) {
        event.preventDefault(); //Stop the pesky default reload function
        setContent(""); //Resets the value of the first input - See #1

        //////START of File Input Reset
        imageInputRef.current.value = "";//Resets the file name of the file input - See #2
        setImage(null); //Resets the value of the file input - See #1
        //////END of File Input Reset
    }

    return (
    <div>
        <form onSubmit={handleSubmit}>
            <input 
            type="text" 
            placeholder="Add Post Content" 
            onChange={event => setContent(event.target.value)}
            value={content} //Make this input's value, controlled by state
            />
            <input 
            type="file"
            onChange={event => setImage(event.target.files[0])} //See Supporting Doc #3
            ref={imageInputRef} //Apply the ref to the input, now it's controlled - See #2
            />
            <button type="submit">Submit Form</button>
        </form>
    </div>
    )
};

Supporting Documentation:

1. useState Hook
   • Returns a stateful value, and a function to update it.
2. useRef Hook
   • If you pass a ref object to React, React will set its current property to the corresponding DOM node whenever that node changes.
3. Using files from web apps
   • If the user selects just one file, it is then only necessary to consider the first file of the list.

Answer 5

I know file input is always uncontrolled however the following code still works in my own porject, I can reset the input with no problems at all.

constructor(props) {
    super(props);
    this.state = {
        selectedFile: undefined,
        selectedFileName: undefined,
        imageSrc: undefined,
        value: ''
    };

    this.handleChange = this.handleChange.bind(this);
    this.removeImage = this.removeImage.bind(this);
}

handleChange(event) {
    if (event.target.files[0]) {
        this.setState({
            selectedFile: event.target.files[0],
            selectedFileName: event.target.files[0].name,
            imageSrc: window.URL.createObjectURL(event.target.files[0]),
            value: event.target.value,
        });
    }
}

// Call this function to reset input
removeImage() {
    this.setState({
        selectedFile: undefined,
        selectedFileName: undefined,
        imageSrc: undefined,
        value: ''
    })
}

render() {
    return (
        <input type="file" value={this.state.value} onChange={this.handleChange} />
    );
}

Answer 6

We can reset file input by using key = {this.state.fileInputKey} and initialsing fileInputKey to Date.now() in constructor state. On file upload success , we need to again assign fileInputKey: Date.now(), so it will have different value than previous and it create new file input component on next render()

We can also do this manually by clicking button to clear/reset file Input

Below is the working code :

import React from "react";
import { Button } from "reactstrap";

class FileUpload extends React.Component {
  constructor(props) {
    super(props);
    this.state = {
      selectedFile: null,
      fileInputKey: Date.now(),
      message: ""
    };
    this.handleClear = this.handleClear.bind(this);
    this.onClickHandler = this.onClickHandler.bind(this);
    this.onChangeHandler = this.onChangeHandler.bind(this);
  }

  onChangeHandler = event => {
    this.setState({
      selectedFile: event.target.files
    });
  };

  onClickHandler = () => {
    if (this.state.selectedFile === null) {
      this.setState({
        message: "Please select File"
      });
      return;
    }
    //axios POST req code to send file to server
    {
      /**        
         const data = new FormData()
    data = this.state.selectedFile[0]                
      axios.post("http://localhost:8080/api/uploadFile/", data)
               .then(res => { 
             if (res.status == 200) {
           // upload success
             }                
               })
               .catch(err => { 
                  //message upload failed
               })    
    */
    }
//after upload to server processed

    this.setState({
      selectedFile: null,
      fileInputKey: Date.now(),
      message: "File Uploaded"
    });
  };

  handleClear() {
    this.setState({
      selectedFile: null,
      fileInputKey: Date.now(),
      message: ""
    });
  }

  render() {
    return (
      <div>
        <input
          type="file"
          key={this.state.fileInputKey}
          class="form-control"
          onChange={this.onChangeHandler}
        />
        <button
          type="button"
          class="btn btn-success btn-block"
          onClick={this.onClickHandler}
        >
          Upload
        </button>
        <Button
          type="button"
          value="Clear"
          data-test="clear"
          onClick={this.handleClear}
        >
          {" "}
          Clear{" "}
        </Button>

        <br />
        <label>{this.state.message}</label>
      </div>
    );
  }
}

export default FileUpload;