Timing of the creation and availability of execution params is undocumented

[bryce-carson]

What would you like to do?

Report an issue on quarto.org

Description

The parameters.html#rendering section doesn't include information on when the execution parameters are available, nor if these are available as objects themselves or if they exist as components of the list params alike in the knitr case.

In my case, I require these parameters to be available within my Quarto R chunks as well as available to any pre-render R scripts or R scripts sourced within inline code in my Quarto front-matter.

[bryce-carson]

I would say this issue is related to #11167 is related in that the behaviour of execution params provided by a file is not well-defined, and insufficiently documented.

[bryce-carson]

Experienced this issue with Quarto 1.6.42

[cderv]

Thanks for the feedback. Your wish is part of a global work regarding Parameters handling in Quarto

• [epic] Improved API for computation parameters  #9197

Currently paramaters are only passed to the computation engine, and the handling is done directly by it

• For engine: knitr this will be knitr direct support
• For engine: jupyter this will be through papermill

So for now, until #9197 brings new support, parameters are limited to be used within computation text, no shortcode, no pre-render script (which are not run by knitr not jupyter).

[bryce-carson]

@cderv, thanks. In a previous version of my document I was not able to access execution params defined in computation chunks at all. I looked for the name of the param as an object in the global environment and also as a component of the list params; neither worked in Quarto 1.6.42. I have updated to Quarto 1.8.17, but I have not tried to reproduce this issue since it was apparent there were limitations to parameters I was not expecting. My team will be using environment variables instead.

The following was a normal knitr computation chunk.

Note that the exact code was not run. I tried enough variations to know that params didn't exist, and the parameters themselves didn't exist as separate objects. I edited some quoted code in a private repo issue to example (only) what sort of thing I tried when using params.

## BEGIN NOT RUN
for (symbol in c("dateBNL", "dateHMISExtract", "dateDashboard", "dateAnnualEnrollments")) {
  if (exists(symbol)) {
    assign(symbol, as_date(get(symbol)))
  } else if (exists(params)) {
    assign(symbol, as_date(params[[symbol]]))
  } else {
    cli::cli_abort("The parameter {.val {symbol}} defined in the {.path {path('params.yml')}} YAML file does not exist in R as a component of the {.val params} list!")
  }
}
## END NOT RUN

I haven't attempted to reproduce this issue on Quarto 1.8.17.

[cderv]

I need some example of what you've tried exactly.

Parametrized report with knitr is a feature already in R Markdown : https://bookdown.org/yihui/rmarkdown/parameterized-reports.html

Quarto offers support by allowing to pass parameters at command line or through a YAML file
https://quarto.org/docs/computations/parameters.html

This is working fine when rendring this doc

---
title: params
params:
  alpha: 0.5
  ratio: 2.0
---

```{r}
params
```

This is alpha params `{r} params$alpha` and ratio params `{r} params$ratio`.

And parameters can be changed at rendering e.g.

quarto render index.qmd -P alpha:1 -P ratio:5

So if you need help making that works in your context, open a discussion item with examples, and we'll be happy to help !

[bryce-carson]

I need some example of what you've tried exactly.

I tried using --execution-params params.yml, with and without a params section in my frontmatter.

I will create and provide a reproducible example for you later (and test it on Quarto 1.6.42 and the latest pre-release).

[cscheid]

and test it on Quarto 1.6.42 and the latest pre-release

Just to clarify: Quarto's stable version is 1.7.