teal.reporter (version 0.6.0)

toHTML.default: Convert report objects to HTML

Description

The toHTML S3 generic method converts various report objects into HTML representations. This is the primary method for rendering report content for display in web browsers, IDE Viewer, or for inclusion in Shiny applications.

Usage

# S3 method for default
toHTML(x, ...)

Value

An HTML representation of the input object. The exact return type depends on the input class:

• For teal_card: A bslib::card() containing all elements

• For code_chunk: A bslib::accordion() with the code

• For plots: A shiny::tags$img() tag

• For text: HTML markup from markdown conversion

• For tables: HTML table elements

All returns are wrapped with htmltools::browsable() to enable viewer display.

Arguments

x

The object to convert to HTML. Supported types include:

• teal_card: A list-like structure containing report elements

• teal_report: A report object containing a teal_card

• ReportCard: Deprecated R6 class for report cards

• code_chunk: Code blocks created with code_chunk()

• chunk_output: Output from evaluated code chunks

• Plot objects: ggplot, recordedplot, trellis, grob

• Table objects: data.frame, rtables, TableTree, ElementaryTable, listing_df, gtsummary, flextable, datatables

• Text: character strings (rendered as markdown)

• Other objects: Conditions, model summaries, etc.

...

Additional arguments passed to methods.

Details

Relationship with teal_card

The teal_card class is a central component in the teal.reporter ecosystem. It is an S3 list where each element represents a piece of report content (text, plots, tables, code chunks, etc.). The toHTML method for teal_card objects:

1. Iterates through each element in the teal_card list

2. Calls toHTML() recursively on each element based on its class

3. Wraps all converted elements in a bslib::card() container

This hierarchical conversion allows complex report structures to be rendered as styled HTML with proper formatting for each content type.

Content Type Conversions

Text and Markdown: Character strings are converted to HTML using CommonMark markdown syntax. Supports headers, lists, code blocks, emphasis, and other markdown features.

Code Chunks: Created with code_chunk(), these are rendered as collapsible Bootstrap accordions with syntax highlighting. The accordion includes the programming language indicator and an icon.

Plots: Plot objects (ggplot, recordedplot, trellis, grob) are converted to PNG images with base64-encoded data URIs, making them self-contained in the HTML output.

Tables: Table objects are converted to styled HTML tables, typically via flextable for consistent formatting.

Viewer Integration

All HTML output is wrapped with htmltools::browsable(), which enables:

• Automatic render in IDE Viewer when displayed interactively

• Proper HTML dependency injection (Bootstrap CSS/JavaScript, Font Awesome icons, etc.)

• Standalone HTML files with all required resources

You can override the browsable behavior with:

print(toHTML(x), browse = FALSE)  # Print markup to console instead

See Also

• teal_report() for creating report objects

• teal_card() for creating report cards

• code_chunk() for creating code blocks

• render() for rendering complete reports to files

Examples

# Initialize empty report
report <- teal_report()

# Add arbitrary markdown elements to the report's teal_card
teal_card(report) <- c(
  teal_card(report),
  "## Document section",
  "Lorem ipsum dolor sit amet"
)

# Use within() to execute code and add code-chunk
report <- within(report, a <- 2)

# within() automatically captures code and outputs
report <- within(report, plot(a))

html <- tools::toHTML(report)
# display HTML markup in viewer
html

# Print HTML markup to console instead of viewer
print(html, browse = FALSE)