Logger {SCDB}

Logger: Complete logging to console, file and database

Description

The Logger class facilitates logging to a database and/or file and to console.

A Logger is associated with a specific table and timestamp which must be supplied at initialization. This information is used to create the log file (if a log_path is given) and the log entry in the database (if a log_table_id and log_conn is given).

Logging to the database must match the fields in the log table.

Value

A new instance of the Logger R6 class.

Active bindings

output_to_console

(logical(1))
Should the Logger output to console? Read only. This can always be overridden by Logger$log_info(..., output_to_console = FALSE).

log_path

(character(1))
The location log files are written (if this is not NULL). Defaults to getOption("SCDB.log_path"). Read only.

log_tbl

(tbl_dbi(1))
The database table used for logging. Class is connection-specific, but inherits from tbl_dbi. Read only.

start_time

(POSIXct(1))
The time at which data processing was started. Read only.

log_filename

(character(1))
The filename (basename) of the file that the Logger instance will output to. Read only.

log_realpath

(character(1))
The full path to the logger's log file. Read only.

Methods

Public methods

• Logger$new()

• Logger$finalize()

• Logger$log_info()

• Logger$log_warn()

• Logger$log_error()

• Logger$log_to_db()

• Logger$finalize_db_entry()

• Logger$clone()

Method new()

Create a new Logger object

Usage

Logger$new(
  db_table = NULL,
  timestamp = NULL,
  output_to_console = TRUE,
  log_table_id = getOption("SCDB.log_table_id"),
  log_conn = NULL,
  log_path = getOption("SCDB.log_path"),
  start_time = Sys.time(),
  warn = TRUE
)

Arguments

db_table

(⁠id-like object(1)⁠)
A table specification (coercible by id()) specifying the table being updated.

timestamp

(POSIXct(1), Date(1), or character(1))
A timestamp describing the data being processed (not the current time).

output_to_console

(logical(1))
Should the Logger output to console?

log_table_id

(⁠id-like object(1)⁠)
A table specification (coercible by id()) specifying the location of the log table.

log_conn

(DBIConnection(1))
A database connection where log table should exist.

log_path

(character(1))
The path where logs are stored. If NULL, no file logs are created.

start_time

(POSIXct(1))
The time at which data processing was started (defaults to Sys.time()).

warn

(logical(1))
Should a warning be produced if no logging will be done?

Method finalize()

Remove generated log_name from database if not writing to a file.

Usage

Logger$finalize()

Method log_info()

Write a line to log (console / file).

Usage

Logger$log_info(
  ...,
  tic = Sys.time(),
  output_to_console = self$output_to_console,
  log_type = "INFO",
  timestamp_format = getOption("SCDB.log_timestamp_format", "%F %R:%OS3")
)

Arguments

...

(character())
Character strings to be concatenated as log message.

tic

(POSIXct(1))
The timestamp used by the log entry.

output_to_console

(logical(1))
Should the line be written to console?

log_type

(character(1))
The severity of the log message.

timestamp_format

(character(1))
The format of the timestamp used in the log message (parsable by strftime()).

Returns

Returns the log message invisibly

Method log_warn()

Write a warning to log file and generate warning.

Usage

Logger$log_warn(..., log_type = "WARNING")

Arguments

...

(character())
Character strings to be concatenated as log message.

log_type

(character(1))
The severity of the log message.

Method log_error()

Write an error to log file and stop execution.

Usage

Logger$log_error(..., log_type = "ERROR")

Arguments

...

(character())
Character strings to be concatenated as log message.

log_type

(character(1))
The severity of the log message.

Method log_to_db()

Write or update log table.

Usage

Logger$log_to_db(...)

Arguments

...

(⁠Name-value pairs⁠)
Structured data written to database log table. Name indicates column and value indicates value to be written.

Method finalize_db_entry()

Auto-fills "end_time" and "duration" for the log entry and clears the "log_file" field if no file is being written.

Usage

Logger$finalize_db_entry(end_time = Sys.time())

Arguments

end_time

(POSIXct(1), Date(1), or character(1))
The end time for the log entry.

Method clone()

The objects of this class are cloneable with this method.

Usage

Logger$clone(deep = FALSE)

Arguments

deep

Whether to make a deep clone.

Examples

  logger <- Logger$new(
    db_table = "test.table",
    timestamp = "2020-01-01 09:00:00"
  )

  logger$log_info("This is an info message")
  logger$log_to_db(message = "This is a message")

  try(logger$log_warn("This is a warning!"))
  try(logger$log_error("This is an error!"))