SDLogger Class Reference

Creates an interface for writing data to a log file on an SD card. More...

#include <SDLogger.hpp>

Collaboration diagram for SDLogger:

Public Member Functions
	SDLogger ()
	Default constructor that performs no initialization.
	SDLogger (std::string filename)
	Constructor to set the file name.
	SDLogger (std::string prefix, int month, int day, int year, std::string filetype)
	SDLogger constructor which takes a prefix + date + filetype based filename.
bool	initialize_sd_card ()
	Call before using SD card interface. Initializes connection to SD card.
void	set_filename (std::string)
	Set the filename to write to the easiest way possible.
void	set_filename (std::string prefix, int month, int day, int year, std::string filetype)
	Slightly more involved but potentially more useful filename creation.
void	write_header (std::vector< std::string > fields)
	Writes a header line to a file using append to prevent overwriting valuable data.
void	log_absolute_mqtt (std::string time, std::string mqtt_topic, std::string mqtt_message)
	Append a line to the target csv file containing an absolute time stamp, mqtt topic, and an mqtt message.
void	log_relative_mqtt (std::string time, int offset, std::string mqtt_topic, std::string mqtt_message)
	Append a line with a relative time stamp to the target file.
void	write_line (std::string line)
	Write a line to the file, will overwrite the contents of the file.
void	append_line (std::string line)
	Open file and append a line, add newline if needed.
void	read ()
	Not implemented
File	open_file (const char *mode=FILE_WRITE)
	Opens the file attached to the logger object with the default mode.
bool	exists (std::string fn)
	File with name fn exists in SD card's filesystem.
bool	exists ()
	File with name stored in this->filename exists in SD card's filesystem.
void	close_card ()
	Close card connection.

Private Attributes
std::string	filename
std::string	filetype = ".csv"
std::string	separator = ";"
SDCard	sd

Detailed Description

Creates an interface for writing data to a log file on an SD card.

A SDLogger is meant to be associated with one file object for the duration of its lifetime.

Constructor & Destructor Documentation

SDLogger()

SDLogger::SDLogger	(	std::string	prefix,
		int	month,
		int	day,
		int	year,
		std::string	filetype
	)

SDLogger constructor which takes a prefix + date + filetype based filename.

Constructs a SDLogger instance with file name by appending all the provided parameters separated by single characters (_, -, .).

<prefix>_<month>-<day>-<year>.<filetype>

Parameters

[in]	prefix	The first part of the filename, identifies purpose of file.
[in]	month	The month the file corresponds to, integer on [1,12].
[in]	day	The day, an integer [1, 31].
[in]	year	The year, ex 2023.
[in]	filetype	The file/data type, ex csv

Member Function Documentation

append_line()

void SDLogger::append_line

(

std::string

line

)

Open file and append a line, add newline if needed.

Appends a line of text to the end of a file's contents. Note that a newline character is appended to the end of the input string to create a "line" and that the file is closed after the operation.

Parameters

[in]

line

The text to append to the end of the file.

close_card()

void SDLogger::close_card

(

)

Close card connection.

Closes the connection to the SD card. This is effectively shutting down the connection through the SPI interface.

initialize_sd_card()

bool SDLogger::initialize_sd_card

(

)

Call before using SD card interface. Initializes connection to SD card.

Returns

true if successfully initialized.

log_absolute_mqtt()

void SDLogger::log_absolute_mqtt	(	std::string	time,
		std::string	mqtt_topic,
		std::string	mqtt_message
	)

Append a line to the target csv file containing an absolute time stamp, mqtt topic, and an mqtt message.

Logs an mqtt topic message to a file. This means that the logged data is timestamped, has a topic, and a message. The line is appended to the file using append_line(string) from this class.

Parameters

[in]	time	The timestamp as a string formatted <date_string>T<time_string>.
[in]	mqtt_topic	The topic string as a <base>/<subtopic>/... formatted string.
[in]	mqtt_message	A string, often JSON object string but not always.

log_relative_mqtt()

void SDLogger::log_relative_mqtt	(	std::string	time,
		int	offset,
		std::string	mqtt_topic,
		std::string	mqtt_message
	)

Append a line with a relative time stamp to the target file.

Logs an mqtt topic message to a file. This means that the logged data is timestamped, has a topic, and a message. The line is appended to the file using log_absolute_mqtt(string) from this class. Essentially a wrapper which adds the offset parameter to provide a relative time estimate in minutes from the previous known time.

Parameters

[in]	time	The timestamp as a string formatted <date_string>T<time_string>.
[in]	offset	The relative offset in minutes, probably calculated from the WDT module reset frequency.
[in]	mqtt_topic	The topic string as a <base>/<subtopic>/... formatted string.
[in]	mqtt_message	A string, often JSON object string but not always.

open_file()

File SDLogger::open_file

(

const char *

mode = FILE_WRITE

)

Opens the file attached to the logger object with the default mode.

Opens a file in one of the two access modes, read only, or read/write.

Parameters

[in]

mode

r, w, etc

Returns

An open file object. If it fails, the error is printed and it should stop execution.

set_filename() [1/2]

void SDLogger::set_filename	(	std::string	prefix,
		int	month,
		int	day,
		int	year,
		std::string	filetype
	)

Slightly more involved but potentially more useful filename creation.

Creates a filename by concatenating the parameters to this method, separated by _, -, .. Unlike set_filename(string) this method allows the user to change the date, prefix and filetype (file extension) associated with the file.

<prefix>_<month>-<day>-<year>.<filetype>

Parameters

[in]	prefix	The first string in the filename, ex log
[in]	month	The month this file was created, ex 09 or september
[in]	day	The day this file was created, ex 12
[in]	year	The year this file was created, ex 2023
[in]	filetype	The filetype/extension of the file, ex .csv or .txt

set_filename() [2/2]

void SDLogger::set_filename

(

std::string

fn

)

Set the filename to write to the easiest way possible.

Stores a file name in this object for repeated access. Use if planning to use this object for operating on one file only.

Parameters

[in]

fn

The file name to open/close.

write_header()

void SDLogger::write_header

(

std::vector< std::string >

fields

)

Writes a header line to a file using append to prevent overwriting valuable data.

Used to initialize a CSV file by writing the list of comma separated fields to the first line of the file. In this case the fields are provided as a vector and are written using write_line(string) so the values overwrite all other data in the file.

Parameters

[in]

fields

A vector list of strings which represent data columns/fields in the CSV file.

write_line()

void SDLogger::write_line

(

std::string

line

)

Write a line to the file, will overwrite the contents of the file.

Write a line to a file, this replaces whatever is currently in the file so use with caution. File is closed at end of operation.

Note that a newline character is appended to the end of the input parameter.

Parameters

[in]

line

The string data which is written as a "line".

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The documentation for this class was generated from the following files:

• lib/SDLogger/SDLogger.hpp
• lib/SDLogger/SDLogger.cpp