Newbie question - Request for simple julia data loader

[gganapat]

A sample julia code data loader would be much appreciated. For example printing a text "Hello world" I had a file with

print("Hello world")

and named it "test.csv.jl" in /docs/data

• If the output is text is it still ok to call the data loader test.csv.jl?
• And is the #!/usr/bin/env julia header needed to get julia to execute the command?
• And I assume this will work only if npm run build is invoked?

I was expecting a file to be generated in /docs/.observablehq/cache but nothing is there when I run npm run build. Any help would be appreciated.

Thanks!

[mbostock]

Yes, you can have a data loader named test.csv.jl and not have it generate CSV — it’s just a little confusing. If you just want a test, maybe call it test.txt.jl instead?

No, the #!/usr/bin/env julia shebang is not necessary if you use the .jl extension for your data loader. A shebang is only necessary when using an executable (.exe) data loader rather than an interpreted one (and in that case, your data loader must also have the executable bit set).

Data loaders are only run if you reference their output. So in addition to writing the data loader, you’ll need to load the file in a Markdown page (or in a JavaScript module that is imported by a Markdown page). If you visit that page in your preview server, it will run your data loader and cache the output. Likewise if you build the site (npm run build), it will run your data loader.

So, if this is your data loader, hello-julia.txt.jl:

print("Hello world")

Here is a corresponding Markdown page that invokes it:

# Hello, Julia

```js echo
FileAttachment("hello-julia.txt").text()
```

You should then see this:

[gganapat]

Thank you!!

[gganapat]

I'm sorry I don't know what I'm doing wrong. I did exactly what you wrote, including just copy/pasting your data-loader file hello-julia.txt.jl into /docs/data folder, created same julia.md file as you did, and ran npm run dev and this is what I get

Running npm run build and followed by npm run dev doesn't help either. There is something about the architecture I'm not able to get a grasp on.

Checking to see if it was a problem with my julia installation, I got no errors.

Thanks,
Gani --

[gganapat]

I did put in docs folder first, then did with /docs/data. But both didn't work.

It appears to hang on a promise as seen in this output---

which I confirmed when I changed julia.md file to

And the julia.md page as below ---

[gganapat]

And with const text = FileAttachment("data/hello-julia.txt").text(); (no / before data) same result.

[mbostock]

You’ve added a leading slash and a trailing semicolon. Here is the code again (with no semicolon so you get implicit display):

FileAttachment("data/hello-julia.txt").text()

Alternatively you can make the await and display explicit as:

const text = await FileAttachment("data/hello-julia.txt").text();

display(text);

[gganapat]

ok, now I'm convinced I'm cursed :)

Data loader

Path for data loader:

julia.md

From terminal

[mbostock]

Are you using an old version of Framework (pre-1.3.0) that doesn’t have built-in support for Julia data loaders maybe?

[gganapat]

I'll download latest one and try again. Thanks for your patience.
gani -

[gganapat]

ok, it works now! I was probably using the older version without support. Would the results have been the same if I had the data loader hello-julia.txt.sh?

#! /usr/bin/env julia
print("Hello from Julia");

in the older version? I seem to remember that being the case.
Thanks again!
gani -

[mbostock]

For a shebang you need to use an executable (.exe) data loader. A shell (.sh) data loader has to be written in your shell’s language (such as bash). An executable data loader also requires the executable bit to be set. So you could put that in hello-julia.txt.exe and then say chmod +x hello-julia.txt.exe and it would work.

[gganapat]

I'm on a Mac, so would it still be .exe? I would have thought it should be hello-julia.txt.sh with right permission as above.

[gganapat]

I confirm it works with .exe. Thanks!