Settings parameters inside _quarto.yml document

[Pierre9344]

Description

Hello,
I use quarto (and R) a lot for my job and my workflow render a website project that reuse a .qmd template I created which I currently duplicates to just modify some parameters in the yaml header of those documents.
My problem is that I end with a lot of duplicated files that are exactly the same except the yaml header and it make my project a mess even using subfolder.
I'm wondering if there is a way to set parameters in the _quarto.yml file so that quarto can create multiple html files from the same qmd document using different parameters.

Example of what I imagine with:

1. QMD template

---
title: |
  `r params$run`
params:
  run: RUN_ID
---
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```{r}
params$run
```

2. _quarto.yml file:

project:
  type: website

format:
  html:
    theme: default
    toc: true
    toc-depth: 3
    code-fold: true
    embed-resources: true

website:
  title: "Example website"
  navbar:
    left:
      - href: index.qmd
        text: Home
     - href: template.qmd
       text: "template rendered with its default parameters"
      - text: "Analysis"
        menu: 
         - text: "analysis 1"
           href: template.qmd
           template:
             file_name: "analysis_run_1"
             params:
               run: run_1
          - text: "analysis 2"
           href: template.qmd
           template:
             file_name: "analysis_run_2"
             params:
               run: run_2

The most problematic aspect I can think would be the naming of the HTML files created by Quarto, but I think this could be resolved by either:

1. Having Quarto use the name of the .qmd file and simply add a number at the end.
2. Adding another file_name argument that Quarto can use directly.

Do you think it could be implemented in future version? I think it would help to automate some workflows.

Best regard!
Pierre

[cderv]

My problem is that I end with a lot of duplicated files that are exactly the same except the yaml header and it make my project a mess even using subfolder.

Regarding YAML header change for configuration but same doc or same project, Quarto offers a special _metadata.yml and metadata-file: options that could be use to externalize (and modify) the YAML
https://quarto.org/docs/projects/quarto-projects.html#directory-metadata

There is also Project profile that allows to run same project or doc render using a different configuration
https://quarto.org/docs/projects/profiles.html

Those are built in options. Other common case for such problems is using .qmd template. For example in R you would use knitr::knit_expand() or whisker or brew package (or any template file package), to create a document and then compile the template to make a proper .qmd with new YAML header. This is usally a good way when you want to create different .qmd with different names. Basically workflow is

Write .qmd as template file using a template syntax -> compile the template using data to create a real .qmd (non template one) and save it with a name -> loop on this and render or just render it

For things like

title: |
  `r params$run`

the new way to do this kind of things would be to create a metadata block to add / modify metadata in the document: https://quarto-dev.github.io/quarto-r/articles/dynamic-metadata.html

I'm wondering if there is a way to set parameters in the _quarto.yml file so that quarto can create multiple html files from the same qmd document using different parameters.

If this the output file name you want to change output-file config is here for this I think.

Hope it helps !