Check if a global data with `page.fileSlug` files exists

[arslabora]

I need to know how can I check in a njk file if another file with a variable name exists. I have the following content source tree:

content/
- items/
- - first.njk
- - second.njk
- - third.njk
etc...

all with "layout": "layouts/item.njk", and

data/
- items/
- - first.json
- - second.json
etc...

For I want is that item.njk layout check if there is a file under data/items with the same name as its owner, under content/items. If so, is shows us the content of it, else tell us that we need to create a file with some content under data/items/{{ fileSlug }}.json

Is it possible?

[thedamon]

I'm in a similar situation. Do you remember if you figured this out?

[pdehaan]

@thedamon You might be able to do this with a custom shortcode or filter. Where the filter checks uses the sync node:fs module to check if the file exists and throw a hard error if the required global data file is missing.

[pdehaan]

eleventy.config.js

const fs = require("node:fs");
const path = require("node:path");

/**
 * @param {import("@11ty/eleventy/src/UserConfig")} eleventyConfig
 * @returns {ReturnType<import("@11ty/eleventy/src/defaultConfig")>}
 */
module.exports = function (eleventyConfig) {
  eleventyConfig.addShortcode("data_file_exists", function (slug) {
    if (!slug) {
      slug = this.page.fileSlug;
    }
    const dataFile = path.join("src/_data/items", `${slug}.json`);
    if (!slug || !fs.existsSync(dataFile)) {
      throw new Error(`Missing data file: "${dataFile}"`);
    }
    return "";
  });

  return {
    dir: {
      input: "src",
      output: "www",
    }
  };
};

src/content/items/third.njk

The "third" fileSlug is optional; the shortcode should default to this.page.fileSlug.

---
---

{%- data_file_exists "third" -%}

<h1>{{ items.third.title }}</h1>

DIRS

tree -A --gitignore

tree -A --gitignore
.
├── eleventy.config.js
├── package-lock.json
├── package.json
└── src/
    ├── _data/
    │   └── items/
    │       ├── first.json
    │       └── second.json
    └── content/
        └── items/
            ├── first.njk
            ├── second.njk
            └── third.njk

5 directories, 8 files

OUTPUT

Missing data file: "src/_data/items/third.json" (via Template render error)

> eleventy

[11ty] Problem writing Eleventy templates: (more in DEBUG output)
[11ty] 1. Having trouble rendering njk template ./src/content/items/third.njk (via TemplateContentRenderError)
[11ty] 2. (./src/content/items/third.njk)
[11ty]   EleventyShortcodeError: Error with Nunjucks shortcode `data_file_exists` (via Template render error)
[11ty] 3. Missing data file: "src/_data/items/third.json" (via Template render error)
[11ty] 
[11ty] Original error stack trace: Error: Missing data file: "src/_data/items/third.json"
[11ty]     at Object.<anonymous> (/private/tmp/11ty-873/eleventy.config.js:15:13)
[11ty]     at Object.<anonymous> (/private/tmp/11ty-873/node_modules/@11ty/eleventy/src/BenchmarkGroup.js:32:26)
[11ty]     at ShortcodeFunction.run (/private/tmp/11ty-873/node_modules/@11ty/eleventy/src/Engines/Nunjucks.js:216:35)
[11ty]     at Template.root [as rootRenderFunc] (eval at _compile (/private/tmp/11ty-873/node_modules/nunjucks/src/environment.js:527:18), <anonymous>:9:76)
[11ty]     at Template.render (/private/tmp/11ty-873/node_modules/nunjucks/src/environment.js:454:10)
[11ty]     at /private/tmp/11ty-873/node_modules/@11ty/eleventy/src/Engines/Nunjucks.js:411:14
[11ty]     at new Promise (<anonymous>)
[11ty]     at /private/tmp/11ty-873/node_modules/@11ty/eleventy/src/Engines/Nunjucks.js:410:14
[11ty]     at Template._render (/private/tmp/11ty-873/node_modules/@11ty/eleventy/src/TemplateContent.js:514:28)
[11ty]     at process.processTicksAndRejections (node:internal/process/task_queues:95:5)
[11ty] Wrote 0 files in 0.03 seconds (v2.0.1)