Using YAML anchors and aliases in _quarto.yml

[jkseppan]

The following _quarto.yml works:

project:
  title: "quarto-test"
  type: book

book:
  chapters:
  - index.md
  - ch1.qmd
  - ch2.qmd
  sidebar:
  - title: sidebar
    contents:
    - index.md
    - ch1.qmd
    - ch2.qmd

But the chapters are listed twice, which is not a big problem in this small example, but imagine a book with thirty chapters. The following passes the http://www.yamllint.com validator but is not accepted by Quarto:

project:
  title: "quarto-test"
  type: book

book:
  chapters: &chapters
  - index.md
  - ch1.qmd
  - ch2.qmd
  sidebar:
  - title: sidebar
    contents: *chapters

Here are the Quarto error messages:

(line 12, columns 5--13) Field "contents" has empty value but it must instead be a string
11:   - title: sidebar
12:     contents: *chapters

In file _quarto.yml
(line 6, columns 3--11) Field "chapters" has empty value but it must instead be an array of values, where each element must be chapter-item
 8:   - ch1.qmd
 9:   - ch2.qmd

Is there a way to include the same list in two places but only have one canonical place to edit the list? Even better if there is a way to concatenate lists - this is not a YAML feature but many CI systems implement some way to specify a flattened list.

[acederberg]

I am wondering the same thing. I wanted to render tex and pdf using the same settings and it is not very dry (don't repeat yourself) to have write it again and again. I wonder what is used to parse the yaml.

Just in case anybody else runs into broken anchoring in my use case, I just used format-links and keep-tex:

format:
  html:
    toc: false
  pdf:
    toc: false
    documentclass: article
    hyperref:
      - pdfborder={0 0 0}
      - breaklinks=false
      - colorlinks=true
      - urlcolor=blue
    include-before-body:
      # NOTE: It may be possible to style links using another means.
      - text: |
          \newcommand{\hreful}[2]{
              \href{#1}{
                  \textcolor{blue}{\ttfamily\underline{#2}}
              }
          }
    geometry:
      - margin=0.7in
    keep-tex: true
    template-partials:
      - ./title.tex
format-links:
  - text: tex
    href: ./index.tex

[mcanouil]

@acederberg format is independent of book. Everything top level (book and project require to be top level as the options under them).
All other options can be applied at the level you want.
In the end, without any example from you, it's very hard to understand what is your use case.

[acederberg]

My use case does not pertain to book format, but rather yaml anchoring. Here is a complete example:

---
# example.qmd
title: Example
format:
  pdf: &pdf_settings
    toc: false
    documentclass: article
    hyperref:
      - pdfborder={0 0 0}
      - breaklinks=false
      - colorlinks=true
      - urlcolor=blue
    include-before-body:
      # NOTE: It may be possible to style links using another means.
      - text: |
          \newcommand{\hreful}[2]{
              \href{#1}{
                  \textcolor{blue}{\ttfamily\underline{#2}}
              }
          }
  latex: *pdf_settings
---

This is an example, and everything pertains to anchoring in the front matter.

The following python code shows how the front matter anchors should resolve

# example.py
import json

import yaml

front_matter = """
title: Example
format:
  pdf: &pdf_settings
    toc: false
    documentclass: article
    hyperref:
      - pdfborder={0 0 0}
      - breaklinks=false
      - colorlinks=true
      - urlcolor=blue
    include-before-body:
      # NOTE: It may be possible to style links using another means.
      - text: |
          \\newcommand{\\hreful}[2]{
              \\href{#1}{
                  \\textcolor{blue}{\\ttfamily\\underline{#2}}
              }
          }
  latex: *pdf_settings
"""


loaded = yaml.safe_load(front_matter)
print(json.dumps(loaded, indent=2))

Running this code gets:

{
  "title": "Example",
  "format": {
    "pdf": {
      "toc": false,
      "documentclass": "article",
      "hyperref": [
        "pdfborder={0 0 0}",
        "breaklinks=false",
        "colorlinks=true",
        "urlcolor=blue"
      ],
      "include-before-body": [
        {
          "text": "\\newcommand{\\hreful}[2]{\n    \\href{#1}{\n        \\textcolor{blue}{\\ttfamily\\underline{#2}}\n    }\n}\n"
        }
      ]
    },
    "latex": {
      "toc": false,
      "documentclass": "article",
      "hyperref": [
        "pdfborder={0 0 0}",
        "breaklinks=false",
        "colorlinks=true",
        "urlcolor=blue"
      ],
      "include-before-body": [
        {
          "text": "\\newcommand{\\hreful}[2]{\n    \\href{#1}{\n        \\textcolor{blue}{\\ttfamily\\underline{#2}}\n    }\n}\n"
        }
      ]
    }
  }
}

However running quarto render example.qmd results in

ERROR: Internal Error: Couldn't locate key include-before-body

This is a bug in quarto. We apologize for the inconvenience.
Please consider reporting it at https://github.com/quarto-dev/quarto-cli. Thank you!

Stack trace:
    at locate (file:///opt/quarto/bin/quarto.js:15010:15)
    at file:///opt/quarto/bin/quarto.js:15035:79
    at ValidationContext.withSchemaPath (file:///opt/quarto/bin/quarto.js:14721:31)
    at file:///opt/quarto/bin/quarto.js:15035:39
    at ValidationContext.withSchemaPath (file:///opt/quarto/bin/quarto.js:14721:31)
    at validateObject (file:///opt/quarto/bin/quarto.js:15029:27)
    at Object.object (file:///opt/quarto/bin/quarto.js:14833:33)
    at schemaCall (file:///opt/quarto/bin/quarto.js:13104:21)
    at file:///opt/quarto/bin/quarto.js:14818:43
    at ValidationContext.withSchemaPath (file:///opt/quarto/bin/quarto.js:14721:31)

which would indicate that something went wrong, possible resolving the anchoring.

[mcanouil]

Thanks!

FYI, this thread is outdated.

• our YAML validator doesn't work well with YAML references #8762

(I believe there is even another one)

[acederberg]

Gotcha. I linked the comment in case it is any help on this issue.