Introduction To Python

1
Introduction To Python

• Scripting language
• Can learn in a day
• Very little typing
• for (i0ilt10i)
• print i - 37 keystrokes
• for i in range(10)
• print i - 27 keystrokes
• python dictionary
• dic 'name''john','age'12
• dic'name' john

2
Perspective

• OSS view point
• End users view point
• Programming in OSS is a collaborative endeavour
  between the programmer and the enduser
• Goal get the enduser to do most of the work

3
Web Programming Basics

• End user should be able to change
• Data stored in a database - postgresql
• Site served by apache
• Business logic scripted in python
• All display handled by templates
• Do not put code in your html
• Do not put html in your code

4
Python CGI Module

• Unlike the perl cgi, there are no methods to
  generate html
• cgitb module
• cgi.FieldStorage()
• has_key()
• getfirst()
• getlist()
• t cgi.FieldStorage()
• if t.has_key('submit')
• name t.getfirst('name')
• cookies

5
Templates

• A good template module
• no programming logic in the template
• does not interfere with the html code
• should be usable by a non programmer
• Cheetah
• t Template(filefilename,dictdict)
• print "Content-Type text/html\n\n"
• print t
• uses for syntax and for variables

6
Database Connection

• Psycopg
• dbi psycopg.connect(dbnamedbname hosthost
  useruser paswordpass)
• con dbi.cursor()
• con.execute("select from table")
• li con.dictfetchall()
• for k in li
• k'date' datetostring(k'date')
• k'amount' str(k'amount').rjust(9)
• gives an list of dictionaries with the column
  names as keys

7
Template 1

• include './hhead.tmpl'
• msg
• lttable class 'main' border1 align'center'gt
• ltform action"manpay.py" method"POST"gt
• lttrgt
• ltthgtEnter Idlt/thgtlttdgtltinput type"text"
  name"tide" value 'parms'tide'' gtlt/tdgt
• lttdgtltinput type"submit" value"Search by tid"
  name"tidesearch"gtlt/tdgt
• lt/trgt
• lt/tablegt
• lttable border"1" cellspacing"0"
  cellpadding"5" class'main' align'center'gt
• lttrgt
• ltth gtSelectlt/thgtltth gtIdlt/thgtltth gtNamelt/thgtltth
  gtAmountlt/thgtltth gtExpireslt/thgtltth gtStatuslt/thgtltth
  gtTransidlt/thgt
• lt/trgt

8
Template 2

• for s in tlist
• lttrgt
• lttd gtltinput type'radio' name'chosen'
  values'description'gtlt/tdgt
• lttd gts'description'lt/tdgt
• lttd gts'name'lt/tdgt
• lttd align'right'gts'amount'lt/tdgt
• lttd gts'expiry'lt/tdgt
• ltTd gts'status'lt/tdgt
• ltTd gts'tid'lt/tdgtlt/trgt
• end for
• lttrgtltTh colspan"4" align"center"gtltinput
  type"submit" value"Mail" name"mail"gtlt/Thgt
• ltTh colspan"4" align"center"gtltinput
  type"submit" value"Delete" name"delete"gtlt/Thgtlt/
  trgt
• lt/tablegtlt/formgt
• include './hfoot.tmpl'

9
Snapshot of Web Page
10
Python script 1
11
Python Script 2
12
Graphics gdmodule

• im gd.image((110,40))
• white im.colorAllocate((255, 255, 212))
• black im.colorAllocate((0, 0, 183))
• red im.colorAllocate((235, 239, 255))
• blue im.colorAllocate((0, 0, 255))
• im.filledRectangle((0,0),(110,40),black)
• im.arc((55,20),(105,36),0,360,white)
• im.fill((55,20),red)
• im.string_ttf(FONT, 10.0, 0.0, (7, y), text,
  black)
• fcStringIO.StringIO()
• im.writePng(f)
• print "Content-Type image/png\n\n", f.getvalue()
• f.close()
• Template
• ltimg src"gddemo.py" gt

13
Session Management

• Http a stateless protocol
• Cookies
• File and database storage
• Session Dictionary elements
• Ttl, first, last, accesses
• Key value pairs for info
• Encryption ezpycrypto module

14
Other Python Modules

• Python Imaging Library
• HTMLgen
• Quixote, PSP, PSO
• Zope and Plone
• Python Hosting
• Learning Python

15
Zope management screen
16
View The Page
17
About

• lawgon_at_thenilgiris.com
• http//avsap.sourceforge.net
• http//digiqual.sourceforge.net
• TkDatePick on cpan