R reference

Load the SDK once at the beginning of an R processing script:

source("/opt/flasktrack/flasktrack.R")

Read inputs

`ft_input_table(name, as_data_frame = TRUE)`

Reads an Arrow table input. It returns a data.frame by default. Set as_data_frame = FALSE to keep the result as an Arrow table.

rows <- ft_input_table("rows")
arrow_rows <- ft_input_table("rows", as_data_frame = FALSE)

Read a declared input only once. Choose the representation you intend to use rather than calling ft_input_table twice.

`ft_input_json(name, simplify_vector = FALSE)`

Reads and decodes JSON.

config <- ft_input_json("config")
threshold <- as.numeric(config$threshold)

Set simplify_vector = TRUE when jsonlite's automatic vector and dataframe simplification is appropriate for the expected document.

`ft_input_file(name)`

Returns the read-only local path for a declared file input.

document_path <- ft_input_file("document")

Additional file readers

text <- ft_input_text("notes")
payload <- ft_input_bytes("payload")
table <- ft_input_csv("csv_file")
table <- ft_input_parquet("parquet_file")

Publish outputs

`ft_output_table(name, value)`

Publishes a dataframe or Arrow-compatible object as an Arrow table.

ft_output_table("result", result)

`ft_output_json(name, value, pretty = FALSE)`

Publishes a value as JSON.

ft_output_json("summary", list(
  accepted = accepted_count,
  rejected = rejected_count
))

`ft_output_file(name, source_path, content_type)`

Publishes an existing file.

ft_output_file("report", report_path, "application/pdf")

Additional file writers

These helpers publish file ports:

ft_output_parquet("dataset", table, compression = "snappy")
ft_output_csv("export", table)
ft_output_text("readme", text, extension = "txt")
ft_output_bytes("image", png_raw, extension = "png", content_type = "image/png")

Execution logs

ft_log("Starting normalization")
ft_log(sprintf("Published %d rows", nrow(result)), "info")
ft_log("No matching rows were found", "warn")

Supported levels are debug, info, warn, and error.

Diagnostics

ft_sdk_info() returns the SDK version and non-secret runtime settings for troubleshooting.