vlib 1.3.2

vlib core libraries

Python Application Development - Core Library Classes

Developed over a period of time to address reoccurring requirements for most all applications. It provides the following modules:

See Pydocs: http://crowfly.net/pydocs/vlib

## Modules

* Configuration File Support

* Database Support

* DataTable Support (an ORM Lite)

* Logging Support (with email Support)

* Object-like (dot) syntax for Dictionaries

* Utilities

## Details

### Configuration Module


The configuration module reads yaml files and provides a dot syntax for expressing nested data trees. ie. self.conf.database.hostname.

Usage:

# To create a singleton instance of configuration data
# found in a yaml file pointed to by an environment
# variable called VCONF
#
# eq.:
# $ export VCONF=$HOME/proj/conf/dev.yml

from vlib import conf
myconf = conf.getInstance()

# Print configuration data, from a Yaml file that looks
# like this:
#
# crew:
# captian: Kirk
# science_officer: Spock

print myconf.crew.captian

# Real world example with Objects

from vlib import conf
class Foo(object):
def __init__(self):
self.conf = conf.getInstance()
self.webserver = self.conf.webserver
self.dbname = self.conf.db.name
...
### Database Module

The database modules provides a simple set of methods for talking to your database, like query(), startTransaction(), commit(), etc.

Usage:

# To setup the Db instance, you need to define the following
# in your config file pointed to by the VCONF environement var.
# The db module uses the conf module to read this information
#
# database:
# engine: mysql
# host: localhost
# db: vlibtests
# user: vlibtests
# passwd: bogangles

from vlib import db
mydb = db.getInstance()

for row in mydb.query('select * from product_types'):
print row['product_type_id']
print row['name']

# Without using config
# --------------------

from vlib import Db
mydb = Db({'engine':'mysql',
'host':'db1',
'db':'books',
'user':'bookmgr',
'passwd':'mepassword',
'dictcursor':True })


# Real world example with Objects
# -------------------------------

from vlib import db

class Books(object):

def __init__(self):
self.db = db.getInstance()

def getBook(self, book_id):
sql = 'select * from books where book_id = %s' % book_id
results = self.db.query(sql)
if results:
return results[0]
return []


# Connecting to multiple databases
# --------------------------------

# Define additional database connections in the config
# ro_database:
# engine: mysql
# host: localhost
# db: vlibtests
# user: vlibtests_ro
# passwd: bogangles

# __ ro/db.py __
from vlib import conf
from vlib.db import singletonFactory

def getInstance():
conf_ = conf.getInstance()
return singletonFactory.create(**conf_.ro_database)

# __ myprog.py __
import ro.db as rodb
my_rodb = rodb.getInstance()
print my_rodb.query('select * from customers')

### DataTable Module

The DataTable module provides a simple abstraction for creating and executing SQL Statements. It relies on the Database Module for connection.

Usage:

from vlib import db
from vlib.datatable import DataTable

mydb = db.getInstance()

books = DataTable(mydb, 'books')
books.setColumns(['book_id as book_id', 'title'])
books.setFilters("created > '2015-05-01'");
for book in books.getTable():
print book

Usage as a base class:

from vlib import db
from vlib.datatable import DataTable

class Books(DataTable):

def __init__(self):
sellf.db = db.getInstance()
DataTable.__init__(self, self.db, 'books')

def report(self):
self.setColumns(['created',
'count(*) as books'])
self.setFilters('created > "2000-01-01"')
self.setGroupBy(1)
return self.getTable()

See, Also:
[DataTable Pydocs](http://crowfly.net/pydocs/vlib/datatable.html)

### Logging Module

The logging module uses log4r to produce consistent log entries that include date, hostname, and class name.

Usage:

# To setup a Logging instance, you define the following in your
# config file. The logging module uses the conf module to read it.
#
# logging:
# filename: /var/log/myapp/myapp.log
# level: DEBUG

# If you want the logger to email you on 'critical' you need
# define email server
#
# email:
# server : smtp.gmail.com:587
# username: [e-mail]
# password: secret
# fromaddr: Myapp Admin [e-mail]

from vlib import logger

class MyClass:

def __init__(self):
self.logger = logger.getLogger(self.__class__.__name__)

def do_something(self):
self.logger.debug('Started doing something')
self.logger.info('Did Something')
self.logger.warn('Warning')
self.logger.error('Did not do something')

# The following we send email:
# self.logger.critical('Something bad happened')

MyClass().do_something()

The above outputs to the log:

2014-02-24 14:41:30 dev1.localdomain DEBUG MyClass Started MyClass.do_something()
2014-02-24 14:41:30 dev1.localdomain INFO MyClass Did Something
2014-02-24 14:41:30 dev1.localdomain WARNING MyClass Warning
2014-02-24 14:41:30 dev1.localdomain ERROR MyClass Did not do something


### Object Dictionary

The **odict** class is syntactic sugar for dealing with dictionaries and nested dictionaries. It privides dot (.) sytax, as well as flower brace ({}) and squre braces ([]) syntax

attr['color'] = 'blue' # normal dict

attr.color = 'blue' # odict

Example 1: This code using dicts …

picture = {'name' : 'The Card Players',
'filename': 'cezanne2.jpg',
'year' : 1895}
print img(src=picture['filename'])

Can be written like this:

from vlib.odict import odict
picture = odict(name = 'The Card Players',
filename = 'cezanne2.jpg',
year = 1895)
print img(src=picture.filename)


Nested Odicts Example:

from vlib.odict import odict
workflow = odict(processes=odict(max_processes=5, debug=False))
for p in workflow.processes.max_processes:
startHandler(workflow.processes.debug)

### Utilities

pretty(X):
Return X formated nicely for the console

str2datetime(s, format="%Y-%m-%d %H:%M:%S"):
Convert str in the form of "2010-11-11 17:39:52" or
"2010-11-11" to a
datetime.datetime Object

str2date(s):
Convert str in the form of "2010-11-11" to a
datetime.date Object

format_datetime(d, with_seconds=False, format=None):
Given a datetime object
Return formated String as follows:

Format: None : 11/22/2013 01:46[:00] am
ISO8601: 2013-11-21T01:46:00-05:00 (EST)

format_date(d):
Given a datetime object
Return a string in the form of "mm/dd/yyyy"

table2csv(data):
Give a LIST or TUPLE
Return: A CSV table as STRING or the input data if not LIST or TUPLE

list2csv(data):
Given a Table of data as a LIST of LISTs
Return in CSV format as a STR

formatdict(d, width=console_width(), indent=0, keylen=0, color=False):
Recursively format contents of dictionaries in sorted tabular order.
Optionally a certain width, indented, and/or a specific key length.

>>> utils.formatdict(batch_item)
active: 1
batch_id: 3250
on_press: None
order_id: 2007372
page_list: None
qty: 2
removed_date: None

uniqueId(with_millisec=False):
Return system time to the millisec as set of numbers

shift(alist):
shift the firt element off of an array and return it

valid_email(email):
Given an email address
Return whether it is in valid format as BOOLEAN



## Installation

__Ubuntu__

Update apt-get to the latest libraries:

apt-get update

Install pip, if you haven't done so already:

apt-get install python-pip
pip install -U pip

Install Mysql DB Connectorm, if you haven't done so already:

apt-get install python-dev libmysqlclient-dev
pip install MySQL-python

Install vweb:

pip install vlib

__Red Hat__

yum install MySQL-python