server side scripting - homepages.math.uic.eduhomepages.math.uic.edu/~jan/mcs275/servscript.pdf ·...

Server Side Scripting

1 a simple Web Calculator

the web interface

html form and Python script

2 A Login Form

the web interface

3 Passing Text and Code

textarea element

running given Python code

MCS 275 Lecture 22

Programming Tools and File Management

Jan Verschelde, 1 March 2017

Programming Tools (MCS 275) server side scripting L-22 1 March 2017 1 / 30

Server-Side Scripting

the web interface

2 A Login Form

the web interface

textarea element

The Web Interfacefor a simple calculator

1 two input elements for two operands

2 select element for the operator

3 checkbox for converting operands to float

4 submit and reset buttons

Result of the Calculationoutput of Python script

Python script writes result inside an h1 header.

the web interface

2 A Login Form

the web interface

textarea element

html form for calculator

<html>

<head>

<title> MCS 275 : a calculator </title>

</head>

<body>

<form method="post"

action="http://localhost/cgi-bin/calculate.py">

<th> 1st operand </th>

<th> operator </th>

<th> 2nd operand </th>

html form continued

the table continued:

<td><input type = "text"

name = "operand1" size="45%"></td>

<option value = "+">+

<option value = "-">-

<option value = "*">*<option value = "/">/

<td><input type = "text"

name = "operand2" size="45%"></td>

</table>

a Checkbox – html form continued

<input name = "convert" type = checkbox

value = True>

convert operands to floats

<input type="submit"

value = "submit calculation">

<input type="reset"

value = "reset the form">

</form>

</body>

</html>

Python script calculate.py

#!/usr/bin/python

import cgi

FORM = cgi.FieldStorage()

print("Content-Type: text/html\n")

ERROR = False

XVAL = FORM[’operand1’].value

except KeyError:

print("please enter first operand")

ERROR = True

YVAL = FORM[’operand2’].value

except KeyError:

print("please enter second operand")

ERROR = True

the script continued

if not ERROR:

CONV = eval(FORM[’convert’].value)

except:

CONV = False

OPER = FORM[’operator’].value

if not CONV:

EXPR = XVAL + ’ ’ + OPER + ’ ’ + YVAL

EXPR = str(float(XVAL)) + ’ ’ + OPER \

+ ’ ’ + str(float(YVAL))

RESULT = EXPR + ’ = ’ + str(eval(EXPR))

print("<html><body>")

print("<h1>%s</h1>" % RESULT)

print("</body></html>")

the web interface

2 A Login Form

the web interface

textarea element

The Web Interface

1 two input elements for name and password2 radio button for new or returning user

Result of the Submitaction by Python script login_form.py

Python script checks whether new or returning user

and confirms the name.

the web interface

2 A Login Form

the web interface

textarea element

html form in the file login_form.html

<html>

<head>

<title> MCS 275 : login form </title>

</head>

<body>

<h1> please register </h1>

action="http://localhost/cgi-bin/login_form.py">

enter your name:

a radio button – html continued

<input type="radio" name="new"

value = True checked> new user

<input type="radio" name="new"

value = False> returning user

<p> enter your password:

<input type="password"

name="password" size ="16">

</body>

</html>

the Python script in the file login_form.py

#!/usr/bin/python

Gets login name and password.

from ast import literal_eval

import cgi

print("Content-Type: text/plain\n")

ERROR = False

NAME = FORM[’login’].value

except KeyError:

print("please enter your name")

ERROR = True

script continued

WORD = FORM[’password’].value

except KeyError:

print("please enter a password")

ERROR = True

if not ERROR:

if literal_eval(FORM[’new’].value):

print(’welcome new user ’ + NAME)

print(’welcome back ’ + NAME)

For new user, check if name does not already exist.

If okay, add to name and password file.

For returning user, check if name already exists on file.

If okay, check if password matches.

the web interface

2 A Login Form

the web interface

textarea element

The Web Interfacefor submitting a text paragraph

Result of the Submitoutput of Python script

the element textarea in give_words.html

<html>

<head>

<title> MCS 275 : enter some text </title>

</head>

<body>

<h1> write a paragraph </h1>

<form method="post"

action="http://localhost/cgi-bin/give_words.py">

<textarea name = "sometext"

rows = 4 cols = 20></textarea>

</form>

</body>

</html>

getting the textarea in give_words.py

#!/usr/bin/python

Illustration of processing a textarea.

import cgi

TEXT = FORM[’sometext’].value

print("your paragraph is \n" + TEXT)

except KeyError:

print("please enter some words")

the web interface

2 A Login Form

the web interface

textarea element

The Web Interfacefor submitting Python code

Result of the Submitoutput of Python script

accepting Python code in run_python.html

<html>

<head>

<title> MCS 275 : run python </title>

</head>

<body>

<h1> run python </h1>

<form method="post"

action="http://localhost/cgi-bin/run_python.py">

give some Python code below:

<textarea name = "code"

rows = 4 cols = 20></textarea>

</form> </body> </html>

getting the Python code in run_python.py

#!/usr/bin/python

Takes the textarea from run_python.html

and runs the code in that element.

import cgi

from os import system

ERROR = False

CODE = FORM[’code’].value

print("your code is \n\n" + CODE)

except KeyError:

print("please enter code")

ERROR = True

running the Python code – script continued

if not ERROR:

FILE = open(’/tmp/code.py’, ’w’)

FILE.write(CODE)

FILE.close()

print("\n... running the code ...\n")

CMD = ’python /tmp/code.py > /tmp/out’

RETVAL = system(CMD)

if RETVAL != 0:

print("the code has an error")

FILE = open(’/tmp/out’, ’r’)

OUTP = FILE.readlines()

print("the output is \n\n", OUTP[0])

Summary and Exercises

Because of security issues, keep working offline.

1 Modify the script give_words.py so it writes the words typed in

the textarea in reverse order.

2 Replace the radio buttons in login_form.html by one

CheckBox "new user".

3 Add to login_form.html a select element offering the options:

instructor, student, and staff.

4 Extend the script login_form.py so it maintains a password

file. For every user there is one line: two strings (name and

password) separated by a colon.

server side scripting - homepages.math.uic.eduhomepages.math.uic.edu/~jan/mcs275/servscript.pdf ·...

Documents

covid-19 infects the u.s. economy - csbs...2020/04/07 ·...

interfacing with...

1 eu strategy for the danube region a new challenge - new...

algebraic varieties and polyhedral...

introduction to cgi programming -...

introduction to computational algebraic geometry jan...

working paper series6dce9947b… · working paper series ....

dawn layer 870.336.1336 • dlayer@familiesinc.net h b...

buckling of scroll waves - university of...

1 macro-regions in the eu - towards a danube strategy...

enumeration and backtracking -...

working with mysql - university of illinois at...

enumeration and backtracking -...

polynomial homotopy continuation -...

from recursion to iteration -...

homotopies for solution...

ordinary differential...

working with mysql - university of illinois at...

the gift wrapping method in phcpack -...

namenlijst eigenaren · 2019. 5. 16. · jan klomburg jan...