Working with file types

Representing files

The specific form a “file” takes can depend on how you reference it.

• When you reference a file in the file system in Origami, Origami uses a FileTree to resolve the reference and return the value as a Node Buffer object.
• When you reference a file on a site via a URL, Origami uses a SiteTree to resolve the reference and return the value as a JavaScript ArrayBuffer.

Unpacking files

Regardless of a file’s representation, you can use Origami path syntax to traverse the file and work with a more meaningful representation that reflects the file’s type. Origami determines how to “unpack” the file contents based on the file extension.

For example, suppose you have a JSON file pet.json containing

{
  "name": "Fluffy",
  "owner": "Alice"
}

If you use the ori CLI to display this file, you will see the plain file contents:

$ ori pet.json
{
  "name": "Fluffy",
  "owner": "Alice"
}

You can unpack this file and traverse into its data with a slash path:

$ ori pet.json/name
Fluffy

Ending a path with a slash unpacks the file and returns all the data. By default, ori will display it in YAML format:

$ ori pet.json/
name: Fluffy
owner: Alice

Standard file types

Origami has built-in support for handling the following types of files.

See below for details on these types.

JavaScript files

Unpacking a .js file returns the file’s default export or, if there are multiple exports, all the exports. If that export is treelike, you can traverse into that export using slash syntax.

Example: If data.js contains

export default {
  a: 1,
};

then you can retrieve traverse the data with a slash path:

$ ori data.js/a
1

JPEG image files

JPEG images can contain metadata in Exif format. You can retrieve this data via slash syntax:

$ ori sample.jpg/caption
A nice photo at the beach

Origami also has a small set of built-in functions called @image for resizing or reformatting images.

JSON files

You can traverse into a JSON file using slash syntax; see Unpacking files above.

Origami files

A file with a .ori extension indicates a file containing an Origami expression. If the result of that expression is treelike you can traverse into it using slash syntax.

If greet.ori contains

{
  name = "Bob"
  greeting = `Hello, !`
}

then you can retrieve a specific value (including any required evaluation) with:

$ ori greet.ori/greeting
Hello, Bob!

Text files

Text files can contain data as front matter in YAML or JSON. You can traverse into the front matter data with slash syntax.

$ cat post1.md
---
title: The First Post
---

Here's the text of my first post.
$ ori post1.md/title
The First Post

Origami assumes that text files are encoded in UTF-8.

YAML front matter can contain Origami expressions.

WebAssembly files

You can traverse into a WebAssembly module, for example, to invoke a function defined in WebAssembly.

If add.wasm exports a function called add that adds two integer arguments, then you can invoke it with:

$ ori "add.wasm/add(1, 2)"
3

This can give you access to functions defined in the many other languages that can be compiled to WebAssembly.

WebAssembly modules run in a “sandbox” that is isolated from your computer so you can download and execute modules directly:

$ ori "(https://webassembly.js.org/example-add.wasm)/add(2, 3)"
5

The parentheses around the URL for a WebAssembly module cause it to be evaluated first, which downloads the module. The / slash after the .wasm causes the downloaded module to be loaded, and the add obtains a function with that name from the module. The final (2, 3) invokes the add function and passes those two values to it.

YAML files

Like JSON files, you can traverse into a YAML file using slash syntax. YAML front matter can contain Origami expressions.

Custom file types

You can tell Origami how to handle other types of files based on their file extension.

Define a handler for a file extension

Suppose your project has .user files that define data about users. For simplicity, let’s assume the contents of a .user file is in plain JSON text.

You can define a JavaScript file user_handler.js:

import { toString } from "@weborigami/origami";

export default {
  mediaType: "application/json",

  unpack: (packed) => {
    const text = toString(packed);
    return JSON.parse(text);
  },
};

The mediaType declaration tells the Origami server to transmit any .user files as JSON. The unpack method defines how to turn the file contents into data. A file may be a Buffer, ArrayBuffer, or other data type depending on where it is stored. The toString() utility function in Origami converts any of those types to plain text. The JSON.parse() call then parses the text into data.

Add your extension handler to your Origami configuration

The second step is to tell Origami to use your user_handler.js file to handle any .user files.

Define a config.ori file at the root of your project. Inside that, define a key user_handler that points to the location of the .js file:

{
  user_handler = src/user_handler.js
}

With that, Origami will call your custom file handler whenever you reference a .user file:

$ cat alice.user
{
  "name": "Alice",
  "location": "Jakarta"
}
$ ori alice.user/
name: Alice
location: Jakarta
$ ori alice.user/name
Alice

Defining a handler for a template language

As a reference example, the Origami Handlebars extension defines a handler for .hbs files that contain Handlebars templates.