Improve user experience for metadata manipulation

[kmasiello]

Metadata may drive inclusion or omission of content divs via .content-visible when-meta= or .content-hidden when-meta= however the implementation for users is a little tough to navigate.

Metadata can be added during execution via something like:

#| output: asis
cat(
  "---",
  paste0("my_metadata": true"),
  "---",
  sep = "\n"
)

or more programmatically:

#| echo: false
import yaml
from IPython.display import Markdown
def quarto_metadata(**kwargs):
    result = "---\n" + yaml.safe_dump(kwargs) + "---\n"
    return Markdown(result)

opts = {}
opts["my_metadata"] = True
quarto_metadata(**opts)

but this is rather abstract for most users. Additionally, there are important elements to understand around order of operations for knitr / jupyter and pandoc.

See rich-iannone/quarto-email#9 for a prime use case, but smoothing out these edges will be relevant beyond conditional emails. Improvements could include wrappers around metadata manipulation to make this more ergonomic.

[mcanouil]

@kmasiello Could you use more backticks to enclose your code cells?
Could you share a small self-contained "working" (reproducible) example to work with, i.e., a complete Quarto document or a Git repository? Thanks.

You can share a Quarto document using the following syntax, i.e., using more backticks than you have in your document (usually four ````).

````qmd
```{r}
#| output: asis
cat(
  "---",
  paste0("my_metadata": true"),
  "---",
  sep = "\n"
)
```
````

[kmasiello]

Hi @mcanouil - please see https://github.com/kmasiello/quarto-metadata

[cscheid]

(@mcanouil I know what this is about, @kmasiello wrote that from my request. We're good, I know what to do. Thanks, folks!)

[cscheid]

The way to solve this is to create a function in the quarto-r and other packages that wraps this behavior.

[cderv]

Thanks for moving the issue @cscheid. I do think this is the solution yes, and I had opened an issue already 😉
So this is now a duplicated of

• Provide a helper function to create metadata yaml block in document body #137

There is a prototype there of what could be done too (#137 (comment))

I'll handle this for a future version