Unexpected parameter values when rendering with quarto_render()

[O-Mohammed]

I have the following .qmd file.

# param_test.qmd
---
title: "Unexpected Parameter values"
format: html
params:
  datetime: "20250815_123413"
  numeric_datetime: 1755261253
---

```{r}
params$datetime
params$numeric_datetime
```

When I render this .qmd using the render button in RStudio, I get these values in my rendered file:

params$datetime
[1] "20250815_123413"

params$numeric_datetime
[1] 1755261253

However, when I render the same .qmd with quarto_render() as below:

quarto::quarto_render(
  "param_test.qmd", 
  output_file = "param_test.html", 
  execute_params = list(
    datetime = "20250815_123413",
    numeric_datetime = 1755261253
  ))

I instead get the following parameter values in my rendered file:

params$datetime
[1] 2.025082e+13

params$numeric_datetime
[1] 1755261300

Results of quarto check

Quarto 1.6.42
[>] Checking environment information...
      Quarto cache location: C:\Users\ozayr.mohammed\AppData\Local\quarto
[>] Checking versions of quarto binary dependencies...
      Pandoc version 3.4.0: OK
      Dart Sass version 1.70.0: OK
      Deno version 1.46.3: OK
      Typst version 0.11.0: OK
[>] Checking versions of quarto dependencies......OK
[>] Checking Quarto installation......OK
      Version: 1.6.42
      Path: C:\Users\ozayr.mohammed\AppData\Local\Programs\Quarto\bin
      CodePage: 1252

[>] Checking tools....................OK
      TinyTeX: (not installed)
      Chromium: (not installed)

[>] Checking LaTeX....................OK
      Tex:  (not detected)

[>] Checking basic markdown render....OK

[>] Checking Python 3 installation....(None)

      Unable to locate an installed version of Python 3.
      Install Python 3 from https://www.python.org/downloads/

[>] Checking R installation...........OK
      Version: 4.5.0
      Path: C:/Users/ozayr.mohammed/AppData/Local/Programs/R/R-4.5.0
      LibPaths:
        - C:/Users/ozayr.mohammed/AppData/Local/Programs/R/R-4.5.0/library
      knitr: 1.50
      rmarkdown: 2.29

[>] Checking Knitr engine render......OK

[cderv]

This is related to other question about YAML handling with quarto_render() function

• See Character object in R as parameter should stays parameter (especially 029 case) #242

And see the new helper function to help with this problem:
https://quarto-dev.github.io/quarto-r/reference/yaml_quote_string.html

quarto::quarto_render(
  "index.qmd", 
  execute_params = list(
    datetime = quarto::yaml_quote_string("20250815_123413"),
    numeric_datetime = 1755261253
  ))

Basically here to explain, when you do

  execute_params = list(
    datetime = "20250815_123413",
    numeric_datetime = 1755261253
  )

This will not write the same YAML as you expect. It will write

  datetime: 20250815_123413
  numeric_datetime: 1755261253

because

yaml::as.yaml(list(
    datetime = "20250815_123413",
    numeric_datetime = 1755261253
  ))  |>  cat()
#> datetime: 20250815_123413
#> numeric_datetime: 1.7552613e+09

So note the missing quotes.

quarto_render() does pass the parameters value to quarto using --execute-params flag, and this requires a YAML following 1.2 spec. yaml R package follows 1.1, and this cause the interpretation by 1.2 spec as a number. Unless you quote it.

Hope it helps understand.