Welcome to use-file-picker 👋

Simple react hook to open browser file selector.

🏠 Homepage

Documentation

Usage

• Simple txt reader
• Image reader
• Advanced usage

API

• Props
• Returns
• Interfaces

Install

npm i use-file-picker or yarn add use-file-picker

StoryBook

https://use-file-picker.vercel.app/

Usage

Simple txt file content reading

https://codesandbox.io/s/inspiring-swartz-pjxze?file=/src/App.js

import { useFilePicker } from 'use-file-picker';
import React from 'react';

export default function App() {
  const [openFileSelector, { filesContent, loading }] = useFilePicker({
    accept: '.txt',
  });

  if (loading) {
    return <div>Loading...</div>;
  }

  return (
    <div>
      <button
        onClick={() => {
          try {
            // you can also get values directly from the openFileSelector
            const result = await openFileSelector();
            console.log('result.errors', result.errors);
            console.log('result.filesContent', result.filesContent);
            console.log('result.plainFiles', result.plainFiles);
          } catch (err) {
            console.log(err);
            console.log('Something went wrong or validation failed');
          }
        }}
      >
        Select files{' '}
      </button>
      <br />
      {filesContent.map((file, index) => (
        <div>
          <h2>{file.name}</h2>
          <div key={index}>{file.content}</div>
          <br />
        </div>
      ))}
    </div>
  );
}

Reading and rendering Images

https://codesandbox.io/s/busy-nightingale-oox7z?file=/src/App.js

import { useFilePicker } from 'use-file-picker';
import React from 'react';

export default function App() {
  const [openFileSelector, { filesContent, loading, errors }] = useFilePicker({
    readAs: 'DataURL',
    accept: 'image/*',
    multiple: true,
    limitFilesConfig: { max: 1 },
    // minFileSize: 0.1, // in megabytes
    maxFileSize: 50,
    imageSizeRestrictions: {
      maxHeight: 900, // in pixels
      maxWidth: 1600,
      minHeight: 600,
      minWidth: 768,
    },
  });

  if (loading) {
    return <div>Loading...</div>;
  }

  if (errors.length) {
    return <div>Error...</div>;
  }

  return (
    <div>
      <button onClick={() => openFileSelector()}>Select files </button>
      <br />
      {filesContent.map((file, index) => (
        <div key={index}>
          <h2>{file.name}</h2>
          <img alt={file.name} src={file.content}></img>
          <br />
        </div>
      ))}
    </div>
  );
}

Advanced usage

https://codesandbox.io/s/musing-moon-wuq4u?file=/src/App.js

import { useFilePicker } from 'use-file-picker';
import React from 'react';

export default function App() {
  const [openFileSelector, { filesContent, loading, errors, plainFiles, clear }] = useFilePicker({
    multiple: true,
    readAs: 'DataURL', // availible formats: "Text" | "BinaryString" | "ArrayBuffer" | "DataURL"
    // accept: '.ics,.pdf',
    accept: ['.json', '.pdf'],
    limitFilesConfig: { min: 2, max: 3 },
    // minFileSize: 1, // in megabytes
    // maxFileSize: 1,
    // readFilesContent: false, // ignores file content
  });

  if (errors.length) {
    return (
      <div>
        <button onClick={() => openFileSelector()}>Something went wrong, retry! </button>
        {errors[0].fileSizeTooSmall && 'File size is too small!'}
        {errors[0].fileSizeToolarge && 'File size is too large!'}
        {errors[0].readerError && 'Problem occured while reading file!'}
        {errors[0].maxLimitExceeded && 'Too many files'}
        {errors[0].minLimitNotReached && 'Not enough files'}
      </div>
    );
  }

  if (loading) {
    return <div>Loading...</div>;
  }

  return (
    <div>
      <button onClick={() => openFileSelector()}>Select file </button>
      <button onClick={() => clear()}>Clear</button>
      <br />
      Number of selected files:
      {plainFiles.length}
      <br />
      {/* If readAs is set to DataURL, You can display an image */}
      {!!filesContent.length && <img src={filesContent[0].content} />}
      <br />
      {plainFiles.map(file => (
        <div key={file.name}>{file.name}</div>
      ))}
    </div>
  );
}

API

Props

Prop name	Description	Default value	Example values
multiple	Allow user to pick multiple files at once	true	true, false
accept	Set type of files that user can choose from the list	"*"	[".png", ".txt"], "image/*", ".txt"
readAs	Set a return type of filesContent	"Text"	"DataURL", "Text", "BinaryString", "ArrayBuffer"
limitFilesConfig	Set maximum and minimum files that user can select	n/a	{min: 1, max: 2}, {max: 1}
readFilesContent	Ignores files content and omits reading process if set to false	true	true, false
minFileSize	Set minimum limit of file size in megabytes	n/a	0.01 - 50
maxFileSize	Set maximum limit of file size in megabytes	n/a	0.01 - 50
imageSizeRestrictions	Set maximum and minimum constraints for image size in pixels	n/a	{ maxHeight: 1024, minWidth: 768, minHeight:480 }
validators	Add custom validation logic	[]	[MyValidator, MySecondValidator]

Returns

Name	Description
openFileSelector	Opens file selector
clear	Clears all files and errors
filesContent	Get files array of type FileContent
plainFiles	Get array of the File objects
loading	True if the reading files is in progress, otherwise False
errors	Get errors array of type FileError if any appears

Custom validation

useFilePicker allows for injection of custom validation logic. Validation is divided into two steps:

• validateBeforeParsing - takes place before parsing. You have access to config passed as argument to useFilePicker hook and all plain file objects of selected files by user. Called once for all files after selection.
• validateAfterParsing - takes place after parsing (or is never called if readFilesContent is set to false).You have access to config passed as argument to useFilePicker hook, FileWithPath object that is currently being validated and the reader object that has loaded that file. Called individually for every file.

interface Validator {
  validateBeforeParsing(config: UseFilePickerConfig, plainFiles: File[]): Promise<void>;
  validateAfterParsing(config: UseFilePickerConfig, file: FileWithPath, reader: FileReader): Promise<void>;
}

Validators must return Promise object - resolved promise means that file passed validation, rejected promise means that file did not pass.

Example validator

/**
 * validateBeforeParsing allows the user to select only an even number of files
 * validateAfterParsing allows the user to select only files that have not been modified in the last 24 hours
 */
const customValidator: Validator = {
  validateBeforeParsing: async (config, plainFiles) =>
    new Promise((res, rej) => (plainFiles.length % 2 === 0 ? res() : rej({ oddNumberOfFiles: true }))),
  validateAfterParsing: async (config, file, reader) =>
    new Promise((res, rej) =>
      file.lastModified < new Date().getTime() - 24 * 60 * 60 * 1000
        ? res()
        : rej({ fileRecentlyModified: true, lastModified: file.lastModified })
    ),
};

Interfaces

LimitFilesConfig

LimitFilesConfig {
	min?: number;
	max?: number;
}

UseFilePickerConfig

UseFilePickerConfig extends Options {
	multiple?: boolean;
	accept?: string | string[];
	readAs?: ReadType;
	limitFilesConfig?: LimitFilesConfig;
	readFilesContent?: boolean;
	imageSizeRestrictions?: ImageDims;
}

FileContent

FileContent {
	lastModified: number;
	name: string;
	content: string;
}

ImageDims

ImageDims {
	minWidth?: number;
	maxWidth?: number;
	minHeight?: number;
	maxHeight?: number;
}

Options

Options extends ImageDims {
	minFileSize?: number;
	maxFileSize?: number;
}

FileError

FileError extends FileSizeError, FileReaderError, FileLimitError, ImageDimensionError {
	name?: string;
}

FileReaderError

FileReaderError {
	readerError?: DOMException | null;
}

FileLimitError

FileLimitError {
	minLimitNotReached?: boolean;
	maxLimitExceeded?: boolean;
}

FileSizeError

FileSizeError {
	fileSizeToolarge?: boolean;
	fileSizeTooSmall?: boolean;
}

ImageDimensionError

ImageDimensionError {
	imageWidthTooBig?: boolean;
	imageWidthTooSmall?: boolean;
	imageHeightTooBig?: boolean;
	imageHeightTooSmall?: boolean;
	imageNotLoaded?: boolean;
}

Authors

👤 Milosz Jankiewicz

• Twitter: @twitter.com/JankiewiczMi/
• Github: @Jaaneek
• LinkedIn: @https://www.linkedin.com/in/jaaneek

👤 Kamil Planer

• Github: @MrKampla
• LinkedIn: @https://www.linkedin.com/in/kamil-planer/

🤝 Contributing

Contributions, issues and feature requests are welcome!
Feel free to check the issues page.

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