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Unified file reading block

read.Rd

A single block for reading files in various formats with smart UI that adapts based on detected file type. Supports both upload and browse modes with persistent storage for uploaded files.

Usage

new_read_block(
  path = character(),
  source = "upload",
  combine = "auto",
  args = list(),
  ...
)

Arguments

path

Character vector of file paths to pre-load. When provided, automatically switches to "path" mode regardless of the source parameter.

source

Either "upload" for file upload widget, "path" for file browser, or "url" for URL download. Default: "upload". Automatically set based on path parameter.

combine

Strategy for combining multiple files: "auto", "rbind", "cbind", "first"

args

Named list of format-specific reading parameters. Only specify values that differ from defaults. Available parameters:

  • For CSV files: sep (default: ","), quote (default: '"'), encoding (default: "UTF-8"), skip (default: 0), n_max (default: Inf), col_names (default: TRUE)

  • For Excel files: sheet (default: NULL), range (default: NULL), skip (default: 0), n_max (default: Inf), col_names (default: TRUE)

...

Forwarded to blockr.core::new_data_block()

Value

A blockr data block that reads file(s) and returns a data.frame.

Details

File Handling Modes

The block supports three modes:

Upload mode:

  • User uploads files via fileInput widget

  • Files are copied to persistent storage directory (upload_path)

  • State stores permanent file paths

  • Works across R sessions with state restoration

Browse mode:

  • User browses file system with shinyFiles

  • Directly selects existing files

  • State stores selected file paths

  • No file copying, reads from original location

URL mode:

  • User provides a URL to a data file

  • File is downloaded to temporary location each time

  • Always fetches fresh data from URL

  • State stores the URL (not file path)

Smart Adaptive UI

After file selection, the UI detects file type and shows relevant options:

  • CSV/TSV: Delimiter, quote character, encoding options

  • Excel: Sheet selection, cell range

  • Other formats: Minimal or no options (handled automatically)

Multi-file Support

When multiple files are selected:

  • "auto": Attempts rbind, falls back to first file if incompatible

  • "rbind": Row-binds files (requires same columns)

  • "cbind": Column-binds files (requires same row count)

  • "first": Uses only the first file

Configuration

The following settings are retrieved from options and not stored in block state:

  • volumes: File browser mount points. Set via options(blockr.volumes = c(name = "path")) or environment variable BLOCKR_VOLUMES. Default: c(home = "~")

  • upload_path: Directory for persistent file storage. Set via options(blockr.upload_path = "/path") or environment variable BLOCKR_UPLOAD_PATH. Default: rappdirs::user_data_dir("blockr")

Examples

if (FALSE) { # \dontrun{
# Basic usage with upload
serve(new_read_block())

# Pre-load specific files
serve(new_read_block(path = c("data.csv", "more_data.csv")))

# Custom CSV parameters (semicolon delimiter, skip first 5 rows)
serve(new_read_block(
  path = "data.csv",
  args = list(sep = ";", skip = 5)
))

# Excel with specific sheet
serve(new_read_block(
  path = "data.xlsx",
  args = list(sheet = "Sales", range = "A1:E100")
))

# URL mode - fetch remote data
serve(new_read_block(
  path = "https://raw.githubusercontent.com/user/repo/main/data.csv"
))
} # }