PYTHON CGI PROGRAMMING
Until now we have learn about what is programming, and several languages of programming such as C, C++, C#, Java, and Python. Now it’s time to take a step further and discuss what is Python CGI programming, how it works, etc. Let’s start from the basics:
What is Python CGI Programming?
Python CGI means “Common Gateway Interface”. It is not a language but just a set of rules that helps in establishing a powerful interaction between the browser and web application. As soon as, the client makes input and sends a request to the webserver, the CGI program sends the output back to the webserver. It also helps in debugging the scripts and lends support to upload files from the forum.
Working on CGI
Common Gateway Interface ( CGI ), uses external script files to handle requests from the client-server to a web server. Moreover, the files can be written in several programming languages. The main objective of the script files is to retrieve the data from the database effectively and efficiently. It converts retrieved data into an Html format and later on the data is sent to the web servers in an Html formatted page.
For example
Note: You should have apache2 installed to execute this example.
#!/usr/bin/python3 # Importing the 'cgi' module import cgi print("Content-type: text/htmlrnrn") print("<html><body>") print("<h1> Hello Program! </h1>") # Using the inbuilt methods form = cgi.FieldStorage() if form.getvalue("name"): name = form.getvalue("name") print("<h1>Hello" +name+"! Thanks for using my script!</h1>") if form.getvalue("happy"): print(" Yayy! I'm happy too! ") if form.getvalue("sad"): print(" Oh no! Why are you sad? ") # Using HTML input and forms method print("<form method='post' action='hello2.py'>") print("Name: <input type='text' name='name' />") print("<input type='checkbox' name='happy' /> Happy") print("<input type='checkbox' name='sad' /> Sad") print("<input type='submit' value='Submit' />") print("</form") print("</body></html>")
Functions of Python CGI
Firstly, you should have a good command over Html to understand the functions and secondly to gain better command over CGI programming you can use following functions:
- cgi.parse(fp=None,environ=os.environ,keep_blank_values=False,strict_parsing=False)
It will parse a query in the environment. The default for a file is sys.stdin.
- cgi.parse_qs(qs,keep_blank_values=False,strict_parsing=False)
It is deprecated and Python keeps it for backward-compatibility. However, urllib.parse.parse_qs() can be used.
- cgi.parse_qsl(qs,keep_blank_values=False,strict_parsing=False)
It can be deprecate too and keeps the backward-compatibility.
- cgi.parse_multipart(fp,pdict)
It will parse the input types of multipart. Moreover, First and second argument takes Input files and dictionary of parameters.
- cgi.parse_header(string)
Further, MIME header can be pass by parse_header() into the main value.
- cgi.test()
It is a test CGI script as well as helps to write HTTP headers and formats.
- cgi.print_environ()
Formats shell environment in HTML.
- cgi.print_form(form)
Formats form in HTML.
- cgi.print_directory()
Format current directory in HTML.
- cgi.print_environ_usage()
Prints environmental variables in HTML.
- cgi.escape(s, quote=False)
Lastly, It converts characters in HTML safe sequence.
Also Read: Top 10 In-Demand programming languages
Syntaxes use in Python CGI
- Content or Type: text/HTML
- Location: URL
- Expires: Date
- Content-Length: N
- Set-Cookie: String
Environmental Variables – CGI
- CONTENT TYPE: It can be used to describe data and its type.
- CONTENT LENGTH: It defines the length of information.
- HTTP COOKIE: If the user sets a cookie for a certain situation. Further, it is used for the same.
- HTTP USER -AGENT: If you need to view the type of browser the user is using. So, you can use this variable.
- REMOTE HOST: Define the hostname of the visitor.
- PATH INFO: Define the path of the CGI script.
- REMOTE ADDR: If you need to know the IP address of the visitor. So, you can use this variable.
- REQUEST METHOD: It can be used to request via POST or GET.
The advantages of Python CGI
- Python CGI can work on any servers and operating servers.
- It can use several languages as it is independent.
- They have a hierarchical nature that means they can perform both simple and complex task.
- Python CGI establishes powerful communication between the browser and web applications.
- It can help you earn more money.
- Lastly, it helps Businesses gain profit as CGI decreases the development and maintenance cost.
The disadvantage of Python CGI
- A lot of traffic gets created as the interpreter has to evaluate a CGI script.
- CGI programs have complex programming and designing.
- The server security may get compromised because most of the CGI programs are free.
Conclusion
This brings us to the end of the article, We hope that it will give you a better understanding of Python CGI as well as its functions. Python is one of the most used programming languages in the industry today. We also bring you the list of top websites from where you can learn Python. Besides, to learn CGI, it can help you with better opportunities in the industry. Therefore, keep practicing the examples to gain dynamic command over Python CGI.
