Add .pdf export for books#443
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Add `.pdf` to any book URL to download a PDF, mirroring the `.md` export. The PDF has a full-bleed cover, a linked table of contents, and numbered pages. Defaults to US Letter; `.A4.pdf` produces an A4 version. Rendered with Prawn from each page's markdown source, walking the Redcarpet HTML with Nokogiri. Bundles the Inter font (OFL) so non-Latin text renders without any system font dependency.
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Pull request overview
This PR adds first-class PDF export for books by supporting the .pdf format on BooksController#show, generating PDFs via a new Book::Pdf Prawn renderer, and exposing the export via an alternate link tag (mirroring the existing .md export behavior).
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Changes:
- Add
.pdf(and.A4.pdf/.letter.pdf) routing and controller handling for book PDF export with conditional GET support. - Introduce
Book::Pdfto render covers, TOC, and leaf content into a Prawn-generated PDF (including bundled Inter font licensing). - Add model/controller tests covering PDF rendering, routing, and basic caching behavior.
Reviewed changes
Copilot reviewed 8 out of 13 changed files in this pull request and generated 5 comments.
Show a summary per file
| File | Description |
|---|---|
| test/models/book/pdf_test.rb | Adds coverage for PDF rendering validity, page size selection, and non‑Latin content. |
| test/controllers/books_controller_test.rb | Adds request-level tests for PDF responses, alternate link tag, and conditional GET behavior. |
| Gemfile.lock | Locks new dependencies required for PDF generation (Prawn + transitive deps). |
| Gemfile | Adds prawn dependency for PDF rendering. |
| config/routes.rb | Adds a sized PDF route (.A4.pdf / .letter.pdf) alongside existing book show routing. |
| app/views/books/show.html.erb | Adds an <link rel="alternate" type="application/pdf"> for PDF export discovery. |
| app/models/book/pdf.rb | Implements the PDF renderer (cover, TOC, per-leaf rendering) using Prawn/Nokogiri. |
| app/controllers/books_controller.rb | Serves PDFs from show and applies conditional GET headers. |
| app/assets/fonts/inter/OFL.txt | Includes Inter font license text for bundled font distribution. |
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| format.pdf do | ||
| size = pdf_page_size | ||
| # Conditional GET: skip regeneration when the book is unchanged. | ||
| if stale?(etag: [ @book, size ], last_modified: @book.updated_at, public: @book.published?) | ||
| send_data Book::Pdf.new(@book, @leaves, page_size: size).render, | ||
| filename: pdf_filename(size), type: "application/pdf", disposition: "inline" | ||
| end | ||
| end |
| end | ||
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| # PDF page size via suffix: `.pdf` defaults to Letter; `.A4.pdf`/`.letter.pdf` force a size. | ||
| get "/:id/:slug.:size.pdf", to: "books#show", constraints: { id: /\d+/, size: /A4|letter/i }, |
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| require "prawn" | ||
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| when "code" then escape(node.text) # no monospace face bundled | ||
| when "br" then "\n" | ||
| when "a" then %(<link href="#{escape(node["href"])}">#{inline(node)}</link>) | ||
| else inline(node) |
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| test "editing a book busts the pdf cache" do | ||
| get book_slug_path(books(:handbook), format: :pdf) | ||
| etag = response.etag | ||
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| books(:handbook).update!(title: "Renamed") | ||
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| get book_slug_path(books(:handbook), format: :pdf), headers: { "If-None-Match" => etag } | ||
| assert_response :success | ||
| end | ||
| end |
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Adding
.pdfto a book's URL downloads it as a PDF, the same way.mdalready returns its markdown. There's no new UI —/1/the-writebook-manual.pdfjust works, with a<link rel="alternate">alongside the markdown one.The PDF keeps the cover (full-bleed), opens with a linked table of contents that mirrors the sidebar, and numbers the pages. It renders with Prawn straight from each page's markdown source — the same content
.mdexports — so there's nothing to keep in sync. Pages, sections and pictures each get their own layout; images and tables are placed directly, since flowing text can't size them. US Letter is the default,.A4.pdfgives A4, and unchanged requests get a 304 instead of re-rendering.It's pure Ruby — no headless browser, no wkhtmltopdf, nothing new in the Docker image. The one real cost is the bundled Inter font (~1.4 MB, OFL): Prawn's built-in fonts only cover Windows-1252, and a book can be in any language, so the font ships with the app to keep rendering deterministic. If you'd rather not carry it, I'm glad to drop it and fall back to the built-in fonts for Latin.
Controller and renderer are tested and the suite is green. Happy to trim the scope or change the approach — let me know.
Examples: