Node-Metadata

An advanced Node.js interface to the exiftool. 🚀

“An amazing level of senseless perfectionism, which is simply impossible not to respect.”

Exiftool is an amazing tool written by Phil Harvey in Perl which can read and write metadata to a number of file formats. This library supports streams. So, you don't have to handle anything from your end. It also cache network files to save your bandwidth.

Requirements
API
Advanced
Experimental Features
Test
- Jest
Tools
Known Issues
Sponsor
License

Install

npm install @enviro/metadata

Requirements

Exiftool need perl to be installed on your system, Download Perl.
Node.js version >= 16.x
ExifTool is no longer included with this package, Download ExifTool.
Read more about seamless ExifTool integration using path option in documentation.

Import & Configure

import Metadata from "@enviro/metadata";

// OPTIONAL
// only required if you are using user-defined tags
async function config() {
    await Metadata.configurator({
        default: true,
        no_cache_cleanup: true,
        tags: [
            {
                name: "CUSTOM_TAG",
                type: "string",
                exifPropGroup: "Exif",
                exifPropSubGroup: "Main",
            },
            {
                name: "CUSTOM_TAG",
                type: "string",
                exifPropGroup: "PDF",
                exifPropSubGroup: "Info",
            },
        ],
    });
}

Options

Name	Type	Description
`default`	`boolean`	[Advanced] Default `undefined` The default configuration use hex keys in file. If you want to use key name in file, set this option explicitly `false`.
`keyCodeEvaluator`	`number`	[Advanced] The value must be greater than 53248. This is the default key for the first user-defined tag.
`no_cache_cleanup`	`boolean`	This will stop auto cache cleaner on node server startup.
`tags`	`[ExifCustomTag]`	Configure Exiftool to add or remove new metadata tags to the file.

ExifCustomTag

Name	Type	Description
`name`	`string`	The name of the custom tag.
`type`	`"string"`	Type of the custom tag's value. You can pass custom valid type in here which is supported by exif tag group.
`exifPropGroup`	`"Exif"`\|`"PDF"`\| `string`	The custom tag's belongs to this group. Custom group can be passed as an argument. Read more at Family 0 (Information Type)
`exifPropSubGroup`	`"Main"`\|`"Info"`\| `string`	The custom tag's belongs to this specific sub group. Custom sub-group can be passed as an argument. Read more at Family 1 (Specific Location)

API

Extract Metadata

Local File

async function read() {
    try {
        const metadata = await Metadata.get("test.pdf", {
            // path not required, since ExifTool is accessible from terminal using exiftool.
            // path: "exiftool",
            tags: [
                {
                    name: "FileName",
                    exclude: true,
                },
            ],
        });
        console.log(metadata);
    } catch (e) {
        console.error(e);
    }
}

Output

[
    {
        FileSize: "89 kB",
        FileModifyDate: "2022:11:11 17:08:58+05:00",
        FileAccessDate: "2022:11:11 17:08:58+05:00",
        FileInodeChangeDate: "2022:11:11 17:08:58+05:00",
        FilePermissions: "-rwxrwxrwx",
        FileType: "PDF",
        FileTypeExtension: "pdf",
        MIMEType: "application/pdf",
        PDFVersion: 1.3,
        Linearized: "No",
        Encryption: "Standard V1.2 (40-bit)",
        UserAccess:
            "Print, Copy, Annotate, Fill forms, Extract, Assemble, Print high-res",
        CreateDate: "2001:10:26 13:39:34",
        Producer: "Acrobat Distiller 4.05 for Windows",
        ModifyDate: "2001:10:26 13:40:41-04:00",
        Title: "PDF Bookmark Sample",
        Author: "Accelio Corporation",
        PageCount: 4,
    },
];

FileName excluded from the result.

File Stream

import { createReadStream } from "node:fs";

async function streamFile() {
    try {
        const rs = createReadStream("sample.pdf");
        const metadata = await Metadata.get(rs, {
            path: "path/to/ExifTool",
        });
        console.log(metadata);
    } catch (e) {
        console.error(e);
    }
}

Network Stream

async function streamURL() {
    try {
        const metadata = await Metadata.get(
            "https://www.w3.org/WAI/ER/tests/xhtml/testfiles/resources/pdf/dummy.pdf",
            {
                no_cache: true,
            }
        );
        console.log(metadata);
    } catch (e) {
        console.error(e);
    }
}

Options

Name	Type	Description
`fileName`	`string`	Read: Cache file name.
`no_cache`	`boolean`	This option doesn't work on local file path passed as a parameter. `no_cache: true` default for stream, read more about Stream caching. `no_cache: false` default for network file, read more Network stream.
`tags`	`[ExifReadOPTag]`	Filter the output metadata tags either excluded them or only include them.
`all`	`boolean`	Default `false` If `true`, all the metadata tags will be returned. This will override the `tags` option. NOTE: This option can cause significant performance issues. Use it only if you need all the metadata tags.
`batch`	`BatchReadOptions`	Options for batch processing.

ExifReadOPTag

Name	Type	Description
`name`	`string`	Name of the metadata tag.
`exclude`	`boolean`	`exclude: true` exclude this tag from the result. `exclude: false` make this tag exclusive.
`custom`	`string`	[Advanced] Custom Exiftool reading command can be directly passed to `custom`. Read more about exiftool commands.

BatchReadOptions

Name	Type	Description
`no_network_cache`	`boolean`\|`[string]`	Default `false`. If `true`, the network files will not be cached. If specified list of URLs provided, than that URLs will not be cached.
`no_stream_cache`	`[string]`	Default `null`. If file name is not valid for stream perspective, then that specific stream will not be cached. `[]` or `null` means all streams will be discarded after reading metadata.

Add/Edit Metadata

Local File

async function write() {
    try {
        const metadata = await Metadata.set("sample.pdf", {
            tags: [
                {
                    name: "CUSTOM_TAG",
                    value: "custom value",
                },
            ],
        });
        console.log(metadata);
    } catch (e) {
        console.error(e);
    }
}

File Stream

async function streamFile() {
    try {
        const rs = createReadStream("sample.pdf");
        const metadata = await Metadata.set(rs, {
            path: "path/to/ExifTool",
            tags: [
                {
                    name: "CUSTOM_TAG",
                    value: null,
                },
            ],
        });
        console.log(metadata);
    } catch (e) {
        console.error(e);
    }
}

An empty tag will delete the tag from the file.

Network Stream

async function streamURL() {
    try {
        // NOTE: This pdf has a size of 26 MB
        const metadata = await Metadata.set(
            "https://research.nhm.org/pdfs/10840/10840.pdf",
            {
                path: "path/to/ExifTool",
                new: true,
                prev: true,
                tags: [
                    {
                        name: "CUSTOM_TAG",
                        value: "NEW VALUE",
                    },
                ],
            }
        );
        console.log(metadata);
    } catch (e) {
        console.error(e);
    }
}

OUTPUT

{
    message: 'File updated successfully!',
    // Path to the file which metadata was edited
    file: '../../dir/to/the/sample.pdf',
    // OR
    // This type of path will be generated for streams
    file: '../../path/to/dir/.tmp/0b00f9b2-cc7d-48b6-8fad-d7e2992de663'
}

Options

Name	Type	Description
`fileName`	`string`	Custom cache file name.
`metadata`	`boolean`	*Default* `false`. Returns the metadata of the file before modifying metadata will be returned.
`new`	`boolean`	[!] Priority `new` > `metadata`. *Default* `false`. Returns the metadata of the file after modifying metadata will be returned.
`all`	`boolean`	Default `false`. If `true`, all the metadata tags will be returned. This will override the `tags` option. NOTE: This option can cause significant performance issues. Use it only if you need all the metadata tags.
`delete_all`	`boolean`	🔴 [UNSAFE] Default `false`. If `true` all the metadata tags will be deleted from the file. New `tags` will remain unaffected.
`tags`	`[ExifWriteOPTag]`	Add new or edit existing metadata tags to the file.

ExifWriteOPTag

Name	Type	Description
`name`	`string`	The name of the metadata tag. If it's a custom tag, make sure to initialize the `Metadata.configurator()`
`value`	`any`\|`null`	The value of the metadata tag. If the tag has no value then it will be removed from the file.
`custom`	`string`	[Advanced] Custom Exiftool writing command can be directly passed to `custom`. Read more about ExifTool commands.
`empty_tag`	`boolean`	❌ [DEPRECATED] Delete the current tag's value without deleting the whole tag from the file.

Copy Metadata

This function allows to copy the metadata from one file or directory to another file or directory.

async function copyFromFileToStream() {
    try {
        const stream = createReadStream("/path/to/dir/img_2.jpg");
        const result = await Metadata.copy(
            "/path/to/dir/img_1.jpg",
            stream,
            {
                path: "path/to/ExifTool",
                src: {
                    tags: [
                        {
                            name: "Author",
                        },
                    ],
                },
                dst: {
                    tags: [
                        {
                            name: "Author",
                        },
                    ],
                },
            }
        );
        console.log(JSON.stringify(result, null, 2));
    } catch (e) {
        console.error(e);
    }
}

The above code will copy the Author tag from image img_1.jpg and set it to img_2.jpg, but dst overrides the Author tag to be deleted. Hence, the tag will be removed from the image img_2.jpg.

Read/Write Options

These options can be passed to read, write, and copy methods.

ExifMetadataReadWriteOptions

Name	Type	Description
`path`	`string`	[Required] Default `'exiftool'`. The path of the ExifTool binaries. NOTE: If exiftool is callable from CLI as `perl exiftool`, then `path` is optional.
`config`	`string`	[Advanced] The path to the config file to use with exiftool.
`del_cache_on_error`	`boolean`	Default `false` If `true`, the temporary file will be deleted if an error occurs. Recommended to use with stream cache.
`stream`	`boolean`	[Advanced] Default `false`. If `true`, instead of returning metadata in a JSON compatible object, an instance of readable stream containing metadata string will be returned. NOTE: This option will return raw metadata instead of JSON, custom parser will be required to parse JSON. JSON.parse() will always throw an error with `fast: true`.

Cache

Manually remove all cache.

Metadata.clear();

Disable network caching.

async function streamURL() {
    const metadata = await Metadata.get("https://example.com/imagine.pdf", {
        no_cache: true,
    });
    console.log(metadata);
}

Explicitly set no_cache: true to disable caching for network file.

Enable stream caching.

async function streamFile() {
    const rs = createReadStream("sample.pdf");
    const metadata = await Metadata.get(rs, {
        no_cache: false,
    });
}

Explicitly set 'no_cache' to false to enable caching for stream.

Advanced

Custom Configuration

If Metadata.configurator does not meet the requirements. You can provide a custom configuration file with Metadata.get() or Metadata.set() function options.

sample.cfg

# Example config file
%Image::ExifTool::UserDefined = (
    'Image::ExifTool::Exif::Main' => {
        d000 => {
            Name => 'CUSTOM_TAG',
            Writable => 'string',
        },
    },
    'Image::ExifTool::PDF::Info' => {
        CUSTOM_TAG => {
            Name => 'CUSTOM_TAG',
            Writable => 'string',
        },
    },
);
1; #end

Use custom configuration

async function read() {
    try {
        const metadata = await Metadata.get("image.jpg", {
            config: "../path/to/sample.cfg",
        });
        console.log(metadata);
    } catch (e) {
        console.error(e);
    }
}

Custom cache file name

This library does not support caching for stream passed as a parameter in such case you should provide something that could identify the cache file later. If you do not provide a cache file name a random name will be generated.

no_cache: false will be ignored for stream passed as a parameter, if fileName is not provided.
```
import { createReadStream } from "node:fs";

const rs = createReadStream("sample.pdf");
const metadata = await Metadata.get(rs, {
    fileName: "sample.pdf",
    no_cache: false,
});
console.log(metadata);
```

Performance

There is a significant overhead in loading ExifTool, so performance may be greatly improved by taking advantage of ExifTool's batch processing capabilities.

Batch Processing

This allows to process multiple files in one function call, and helps to reduce the startup overhead. Sample batch processing code can be found in the examples/batch directory.

Read Metadata

async function readMultipleFromDisk() {
    try {
        const metadata = await Metadata.get([
            "/path/to/dir/samples/img_1.jpg",
            "/path/to/dir/samples/img_2.jpg",
            ...
        ]);
        console.log(metadata);
    } catch (e) {
        console.error(e);
    }
}

Edit/Write Metadata

async function writeMultipleFromDirectory() {
    try {
        const metadata = await Metadata.set("../../path/to/dir", {
            new: true,
            metadata: true,
            tags: [
                {
                    name: "Author",
                    value: "John Doe",
                },
            ],
        });
        console.log(JSON.stringify(metadata, null, 4));
    } catch (e) {
        console.error(e);
    }
}

CLI

To execute complex or direct access to ExifTool use CLI method.

const command = `-j ~/path/to/file`;
const subscriberId = Metadata.CLI.run(command || commands, (err, data) => {
        console.log(err || data);
        Metadata.CLI.stop(subscriberId);
    }, {
        path: exifToolPath
    });

⚠️ NOTE: If the command contains arbitrary spaces, use array syntax to avoid confusion.
Example:

const command = [
    '-j',
    '-Author="Foo Bar"',
    '"~path/to/file/containing spaces/file name.pdf"'
]

Remove CLI events listener

Remove the current CLI events listener once the task is finished to avoid receiving metadata for additional CLI tasks. Use "queue" option, which will handle everything for you.

Metadata.CLI.stop(subscriberId);

Exit CLI

This will automatically terminate the CLI process and all events listeners.

Metadata.CLI.kill();

More examples: examples/raw.js

Options

Name	Type	Description
`path`	`string`	[Required] The path to the ExifTool binary. NOTE: `path` is optional, if ExifTool is callable from the CLI as `perl exiftool`.
`config`	`string`	The configuration file path.
`raw`	`boolean`	[Advanced] Default `false` If `true`, the child process will be returned.
`streams`	`boolean`	[Advanced] Default `false` If `true`, raw streams will be returned.
`queue`	`boolean`	[Advanced] Default `false` If `true`, the stream observer will serve streams in queued order and will remove the callback from the stream observer once the command is fulfilled successfully or not.

⚠️ Experimental Features

Experimental features can be unstable or maybe subject to change, using them in a production environment is not recommended.

Name	Type	Description
`fast`	`boolean`	[Advanced] Default `false` If `true`, a dedicated process will be started for the binaries. This can significantly increase performance. To exit `fast` mode, use `Metadata.stop();`

NOTE

The package is pure ESM. It cannot be require() from CommonJS.
Future version might break backward compatibility.
Check release notes for breaking changes.

Future

This library is currently rewritten in TypeScript.
fast mode will be enabled by default.

Examples

Examples can be found inside example directory.

Tools

Comming Soon

Known Issues

If you discover any bug, create an issue.

Sponsor

Support this project.

License

MIT

@enviro/metadata

Node-Metadata

Table of Contents

Install

Requirements

Import & Configure

Options

ExifCustomTag

API

Extract Metadata

Local File

Output

File Stream

Network Stream

Options

ExifReadOPTag

BatchReadOptions

Add/Edit Metadata

Local File

File Stream

Network Stream

OUTPUT

Options

ExifWriteOPTag

Copy Metadata

Read/Write Options

ExifMetadataReadWriteOptions

Cache

Manually remove all cache.

Disable network caching.

Enable stream caching.

Advanced

Custom Configuration

sample.cfg

Use custom configuration

Custom cache file name

Performance

Batch Processing

Read Metadata

Edit/Write Metadata

CLI

Remove CLI events listener

Exit CLI

Options

⚠️ Experimental Features

NOTE

Future

Examples

Tools

Known Issues

Sponsor

License

Readme

Keywords

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Install

Repository

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