#Reading data from `package.json`

12 messages · Page 1 of 1 (latest)

vapid quiver
#

How can I read the version value from package.json and store it as a variable to be used in templates?

fierce carbonBOT
#

Hi @vapid quiver. I'm kapa.ai, your friendly support bot. I will try to answer your question by searching through the knowledge base. :wave:

#

You can read the version value from package.json in your Astro project by using Node.js built-in fs module. Here's how you can do it:

  1. Import the fs module and use readFileSync to read the package.json file.
  2. Parse the file content with JSON.parse to get a JavaScript object.
  3. Access the version property of the object.

Here's a code snippet demonstrating this:

import { readFileSync } from "fs";
import { fileURLToPath } from "url";

// read package.json
const file = fileURLToPath(new URL("package.json", import.meta.url));
const json = readFileSync(file, "utf8");
const pkg = JSON.parse(json);
console.log("DEBUG pkg:", pkg);

// Now you can access the version
const version = pkg.version;

However, please note that currently, Astro prevents you from accessing Node.js builtins like fs in Astro components. This is partially because that's Snowpack's default behavior, but also because Astro aims to be agnostic to any single runtime if possible. This limitation is discussed in this Github issue (https://github.com/withastro/astro/issues/341).

To use the version value in your Astro templates, you can define it as a variable in your Astro script using JavaScript or TypeScript expressions, and then use these variables in your Astro template inside curly braces { } to tell Astro you’re using some JavaScript. This is explained in the Astro documentation (https://docs.astro.build/en/tutorial/2-pages/3#define-and-use-a-variable).

#

If you want to use the version value in client-side JavaScript, you might need to use Vite's define config to pass the value from server to client. This is discussed in this Github issue (https://github.com/withastro/astro/issues/7416). However, please note that there are some limitations and workarounds related to using vite.define in Astro's defineConfig(), as discussed in this Github issue (https://github.com/withastro/astro/issues/8967).

Note: you can ask me a follow up question by @ mentioning me again :speech_balloon:

#

@vapid quiver kapa.ai is still learning and improving, please let us know how it did by reacting below

vapid quiver
#

@fierce carbon This is the approach I took, and noticed the warning from Astro that mirrors what you said about it being runtime-agnostic. Does this mean there is no effective way for me to programatically ready the version object from package.json?

fierce carbonBOT
#

Let me check the knowledge base for you. One moment! :books:

vapid quiver
#

read*

fierce carbonBOT
#

Astro's runtime-agnostic design does indeed limit direct access to Node.js built-ins like fs in Astro components. However, there are a few proposed solutions and workarounds to this limitation:

  1. Allow import 'fs' and others: If you use them, then you take on the responsibility of being Node-specific. This approach might not be ideal if you want to keep your project runtime-agnostic.

  2. Add some special src/data/ file type: This file will always run server-side during build and has access to Node.js builtins. It's not possible to import these in a route.

  3. Disallow generally, and force you to move this kind of code into an astro.config.mjs file: Here it can be injected into the build as a static value. This approach is discussed in this Github issue (https://github.com/withastro/astro/issues/341).

For example, you can define the version value in astro.config.mjs and use Vite's define config to pass it to your Astro components:

import { defineConfig } from "astro/config";
import { readFileSync } from "fs";
import { fileURLToPath } from "url";

// read package.json
const file = fileURLToPath(new URL("package.json", import.meta.url));
const json = readFileSync(file, "utf8");
const pkg = JSON.parse(json);

export default defineConfig({
  vite: {
    define: {
      PKG_VERSION: pkg.version,
    },
  },
});

Then, in your Astro components, you can access the version value with import.meta.env.PKG_VERSION. However, please note that there are some limitations and workarounds related to using vite.define in Astro's defineConfig(), as discussed in this Github issue (https://github.com/withastro/astro/issues/8967).

#

If you're using SSR, environment variables can be accessed at runtime based on the SSR adapter being used. With most adapters, you can access environment variables with process.env, but some adapters work differently. For the Deno adapter, you will use Deno.env.get(). Astro will first check the server environment for variables, and if they don’t exist, Astro will look for them in .env files. This is explained in the Astro documentation (https://docs.astro.build/en/guides/environment-variables#getting-environment-variables).

Note: you can ask me a follow up question by @ mentioning me again :speech_balloon:

#

@vapid quiver kapa.ai is still learning and improving, please let us know how it did by reacting below

mossy hamlet
#

@vapid quiver if the package version is the only thing you need from package.json, you should be able to use process.env.npm_package_version in your templates