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-storybook-b0wsuz1yj-mrkampla.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={() => openFileSelector()}>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 enought 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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