local-simple-database 0.1.2

Package for easy process variable in file like if it was usual variable in python

Table of Contents

• Short Overview.

• Long Overview.

  • One small example

    • How to name databases

• Installation

• Basic usage.

  • 1) class_local_simple_database

    • Initialization of databases handler

    • A few examples of Usage

      • 1) Integer database

      • 2) Float database

      • 3) Datetime database

      • 4) Date database

  • 2) class_local_dict_database

    • Initialization of databases handler

    • A few examples of Usage

      • 1) Basic store/access/modify data from a dict database.

      • 2) Set default value:

• Advanced usage (can be skipped, you already know enough to use it)

  • 1) class database additional arguments

  • 2) Rolling example

  • 3) Get values for ALL databases in the directory.

• Links

• Project local Links

• Contacts

• License

Short Overview.

local_simple_database is a simple Python package(py>=2.7 or py>=3.4) with the main purpose to help storing and retrieving data from human-readable .txt files with one line of code. All the interactions with files are being made in a processes-threads safe manner.

Long Overview.

This package consists of 2 main classes with which user should interact:

1. class_local_simple_database

2. class_local_dict_database

One small example

Let’s say you want to store file with int variable with name int_times_I_ve_eaten.

Then, using this package, you can do it like this:

from local_simple_database import class_local_simple_database
LSD = class_local_simple_database(path_to_dir_where_to_save_file)

and then just use everywhere in your code LSD[“int_times_I_ve_eaten”] like if it was usual dictionary.

LSD["int_times_I_ve_eaten"] += 1  # To increase value in the file
LSD["int_times_I_ve_eaten"]  # To get current value from the file

After running this code with:

path_to_dir_where_to_save_file = “./folder_with_all_my_databases”

Inside directory ./folder_with_all_my_databases

will be created file “int_times_I_ve_eaten.txt” with current value.

Value is stored in a human-readable .txt file, so you can always access it.

To get it some time later or from another process just use:

int_value_I_was_afraid_to_lose = LSD["int_times_I_ve_eaten"]

How to name databases

Name of database should satisfy template “type_name”

Examples: int_balls, float_seconds_left, str_my_name, dict_useless_heap

So just by the name you can define the type of database, isn’t it awesome.

Installation

• Install via pip:

pip install local_simple_database

Basic usage.

1) class_local_simple_database

This class is built to handle (saving-retrieving) one value data like integer or float.

For now supported types of databases are:

• [“int”, “float”, “str”, “datetime”] (Probably will be enhanced soon)

• This means that one file with database can handle only type data

Initialization of databases handler

from local_simple_database import class_local_simple_database
LSD = class_local_simple_database(
    str_path_database_dir=".",
)

Arguments:

1. str_path_database_dir:

   If the explicit path is not given or variable is not set at all,

   then will be used path “./local_database”

   Folder for database will be created automatically

A few examples of Usage

After you’ve initialized LSD object you can use:

1) Integer database

If you want to store/access/modify simple int in file:

# Process 1
LSD["int_red_cars_drove"] += 1
LSD["int_red_cars_drove"] += 2
# Oh now, last one was burgundy
LSD["int_red_cars_drove"] -= 1

# Process 2
print("red cars already found", LSD["int_red_cars_drove"])
# If there was no such DataBase yet, than in will be created and 0 value will be returned.
LSD["int_red_cars_drove"] = 5
print("Red cars already found: ", LSD["int_red_cars_drove"])

2) Float database

LSD["float_last_price_of_watermelons"] = 7.49
# Too many watermelons this year, need to apply 30% discount
LSD["float_last_price_of_watermelons"] *= 0.7
print(
    "Hello my best customer, current price on watermelons is: ",
    LSD["float_last_price_of_watermelons"]
)

3) Datetime database

import datetime
# Saving datetime in file in ISO format (E.G. 2020-05-16T18:00:41.780534)
LSD["datetime_now"] = datetime.datetime.now()

# Load datetime obj from DataBase
# if DB not found will be retunrs datetime for 1970-01-01
print("Hour was a moment ago: ", LSD["datetime_now"].hour)

# Use DataBase value to find timedelta
int_seconds_gone = (datetime.datetime.now() - LSD["datetime_now"]).seconds
print("Seconds gone: ", int_seconds_gone)

4) Date database

Very similar to datetime database, but only date will by saved

import datetime
# Saving datetime in file in ISO format (E.G. 2020-05-16)
LSD["date_now"] = datetime.datetime.now()

# Load datetime obj from DataBase
# if DB not found will be retunrs datetime for 1970-01-01
print("Date today: ", LSD["date_now"])

# Use DataBase value to find timedelta
if datetime.datetime.now().date() == LSD["date_now"]:
    int_seconds_gone_today = (datetime.datetime.now() - LSD["date_now"]).seconds
    print("Seconds already gone: ", int_seconds_gone_today)

2) class_local_dict_database

This class was built to handle (saving-retrieving) dictionary with data from a file.

Work with such database is a little different from class_local_simple_database so it was necessary to put it in a separate class

Initialization of databases handler

from local_simple_database import class_local_dict_database
LSD = class_local_dict_database(
    str_path_database_dir=".",
    default_value=None,
)

Arguments:

1. str_path_database_dir:

   If the explicit path is not given or variable is not set at all,

   then will be used path “./local_database”

   Folder for databases will be created automatically

2. default_value: value to use for any database if key in it is not found.

   LSD[database_name][key] = default_value

A few examples of Usage

1) Basic store/access/modify data from a dict database.

# Set methods
## Set value for whole LSD:
LSD["dict_very_useful_heap"] = {"Mike": 50, "Stan": 1000000}

## Set keys for one dictionary LSD
## If there is no file with asked dict database then it will be created automatically
LSD["dict_useless_heap"]["random_key"] = 1
LSD["dict_useless_heap"]["random_key"] += 3
LSD["dict_useless_heap"][2] = ["Oh my God, what a list is doing here", "Aaa"]
LSD["dict_useless_heap"][99] = {"Are you serious?": {"You'd better be!": "Bbb"}}

# Get methods
## To get whole dict for LSD, please use:
LSD["dict_useless_heap"].get_value()  # Sorry for that, I don't know how to do it without additional method

## To get string representation of whole dict:
print(LSD["dict_useless_heap"])

## To get one key from dict:
int_random_key = LSD["dict_useless_heap"]["random_key"]

2) Set default value:

# You can set the default value for all databases OR for only one:

## 1) Set default value for any database when can't find key:
LSD.change_default_value(0)

## 2) Set default value for one database:
LSD["cars"].change_default_value(0)

# They you can use LSD similarly to collections.defaultdict
LSD["cars"]["red"] += 1
# Oh no, that was burgundy once again
LSD["cars"]["red"] -= 1
LSD["cars"]["burgundy"] += 1

Advanced usage (can be skipped, you already know enough to use it)

1) class database additional arguments

Both 2 main classes (class_local_simple_database, class_local_dict_database) have additional arguments:

1. str_datetime_template_for_rolling=””

   This variable allows setting rolling save of database results using the DateTime template.

   If the value is not empty, then saving/retrieving results will be done from deeper folders with names satisfy the evaluation of the DateTime string template.

   E.G. To save daily results use “%Y%m%d” (Then deeper folder names will be like “20191230”, “20191231”, …)

   E.G. To save hourly results use “%Y%m%d_%H” (Then deeper folder names will be like “20191230_0”, “20191230_23”, …)

2. float_max_seconds_per_file_operation=0.01

   This variable is necessary for multiprocessing safe work.

   It setting time in which LSD file accessed by process can’t be accessed by any other process.

   By default, it is set to 10 ms for simple database and 20 ms for dict database.

   If you use operations which from accessing value till setting new value needs more time, you are more than welcome to increase it.

   You can set it to 0.0 if you are not using threads-processes and want the maximum speed.

# Full definition of class_local_simple_database
LSD = class_local_simple_database(
    str_path_database_dir=".",
    float_max_seconds_per_file_operation=0.05,
    str_datetime_template_for_rolling=""
)

# Full definition of class_local_dict_database
LSD = class_local_dict_database(
    str_path_database_dir=".",
    default_value=None,
    float_max_seconds_per_file_operation=0.05,
    str_datetime_template_for_rolling=""
)

2) Rolling example

LSD_daily_rolling = class_local_simple_database(
    str_path_database_dir=".",
    str_datetime_template_for_rolling="%Y%m%d"
)

3) Get values for ALL databases in the directory.

To get a dictionary with data in all databases by database name, use:

LSD.get_dict_DBs_data_by_DB_name()

If you were using rolling, then you can get dictionary with results like {“datetime_1”: dict_all_DBs_date_1, }

LSD.get_dict_every_DB_by_datetime()

If you were using rolling, and interested only in one database. {“datetime_1”: database_value_1, …}

# Please replace *str_database_name* on name of LSD which values you want to get
LSD.get_one_DB_data_daily(
    str_database_name,
    value_to_use_if_DB_not_found=None
)

Links

• PYPI

• readthedocs

• GitHub

Project local Links

• CHANGELOG.

• CONTRIBUTING.

Contacts

• Email: [e-mail]

• vk.com

• Facebook

License

This project is licensed under the MIT License.