Databases through Python-Flask and MariaDB

Transcription

1 1 Databases through Python-Flask and MariaDB Tanmay Agarwal, Durga Keerthi and G V V Sharma Contents 1 Python-flask Installation Testing Flask Mariadb Software Installation Configuration Database Application Creating a Database Creating HTML Forms Python Connector from Browser to Database Fetching the stored Data from the Database Updating the Database Linking all modules to create the Database application.. 5 Abstract Databases software applications for small establishments like schools, shops, etc.. can be easily built using the MariaDB database, Python-Flask connector and HTML. This manual shows how to install these free software tools and build a simple application using them. 1 Python-flask Flask is Python framework for creating web applications. 1.1 Installation 1) Run the following commands on the terminal Tanmay is an intern with the TLC, IIT Hyderabad. Durga is a UG student at IIT Hyderabad. *GVV Sharma is with the Department of Electrical Engineering, Indian Institute of Technology, Hyderabad India gadepall@iith.ac.in. All content in this manual is released under GNU GPL. Free and open source. sudo apt g e t u p d a t e sudo apt g e t i n s t a l l python p i p sudo p i p i n s t a l l f l a s k sudo p i p i n s t a l l mysql c o n n e c t o r 1.2 Testing Flask Since installation of Flask is now complete, verify that flask is working by using the example below. 1) Code: from f l a s k i m p o r t F l a s k # Import t h e F l a s k c l a s s app = F l a s k ( name ) # F l a s k t a k e ( name ) as an argument. # / which u r l s h o u l d c a l l t h e a s s o c i a t e f u n c t i o n. d e f s t u d e n t ( ) : r e t u r n H e l l o World # s e r v e r runs i f t h e s c r i p t s e x e c u t e d d i r e c t l y from python i n t e r p r e t e r and n o t used as an i m p o r t e d module. app. run ( ) # runs t h e a p p l i c a t i o n on l o c a l s e r v e r 2) Save the file as hello.py. 3) open the terminal and run python h e l l o. py An ip address will be displayed on the terminal. 4) Open the address on your favourite browser. Hello world will be displayed

2 2 2 Mariadb MariaDB Server is one of the most popular database servers in the world. The following installation instructions are for Ubuntu. Installation on other Linux systems are likely to be similar. 2.1 Software Installation Refer to Link 1) Type the following commands on the terminal sudo apt g e t i n s t a l l s o f t w a r e p r o p e r t i e s common sudo apt key adv recv keys k e y s e r v e r hkp :// k e y s e r v e r. ubuntu. com : xcbcb082a1bb943db sudo add apt r e p o s i t o r y deb h t t p :// m i r r o r. jmu. edu/pub/ /repo/ 5. 5/ ubuntu t r u s t y main sudo apt g e t u p d a t e sudo apt g e t i n s t a l l s e r v e r You may receive the following prompt or something similar: After this operation, 116 MB of additional disk space will be used. Do you want to continue? [Y/n] Enter Y to continue. Next you will be asked: New password for the MariaDB root user: This is an administrative account in MariaDB with elevated privileges; enter a strong password. Then you will be asked to verify the root MariaDB password: Repeat password for the MariaDB root user: That is it! Your basic MariaDB installation is now complete! Be sure to stop MariaDB before proceeding to the next step: sudo service mysql stop 2.2 Configuration Configure and Secure MariaDB for Use 1) Now we will instruct MariaDB to create its database directory structure: sudo mysql install db 2) Start MariaDB sudo service mysql start 3) And now let us secure MariaDB by removing the test databases and anonymous user created by default: sudo mysql secure installation 4) You will be prompted to enter your current password. Enter the root MariaDB password set during installation: Enter current password for root (enter for none): Then, assuming you set a strong root password, go ahead and enter n at the following prompt: Change the root password? [Y/n] n Remove anonymous users, Y: Remove anonymous users? [Y/n] Y Disallow root logins remotely, Y: Disallow root login remotely? [Y/n] Y Remove test database and access to it, Y: Remove test database and access to it? [Y/n] Y And reload privilege tables, Y: Reload privilege tables now? [Y/n] Y 5) Verify MariaDB Installation Check Version mysql -V 3.1 Creating a Database 3 Database Application 1) Open the terminal and type mysql u r o o t p You will be asked for a password. Enter it. 2) Create a database called test using the following command. CREATE DATABASE T e s t ; 3) In order to use the Database type USE T e s t ; You will enter into the Database called Test. 4) Now create a table named test with parameters as Name and Roll Number. CREATE TABLE t e s t ( name v a r c h a r ( 2 0 ) n o t n u l l, r o l l v a r c h a r ( 2 0 ) n o t n u l l ) ;

3 3 varchar(20) means string of size 20 characters. 5) To see the format of the fields in test desc t e s t ; 3.2 Creating HTML Forms 1) Type the following code in a file called student.html and open it using a browser. You will see boxes with Name, Roll. Also, there will be a button called submit and two links titled Show List and Update. the <form a c t i o n = / a c t method= POST > <p>name< i n p u t t y p e = t e x t name = name /></ p> <p>roll< i n p u t t y p e = t e x t name = r o l l /> </ p> <p>< i n p u t t y p e = submit v a l u e= submit /></ p> <p><a h r e f= / d i s p l a y > Show L i s t</ a></ p> <p><a h r e f= / u p d a t e > Update</ a></ p> </ form> 2) Type the following code in a file called message.html. The purpose of this file is to display status messages. <p> o u t p u t :{{msg}}</ p> 3) Save both the html files in a folder called templates. 3.3 Python Connector from Browser to Database 1) Type the following code in a file called store.py. d e f s t u d e n t ( ) : s t u d e n t. html r o u t e ( / a c t, methods =[ GET, POST ] ) d e f a c t ( ) : i f ( r e q u e s t. method == POST ) : t r y : name= r e q u e s t. form [ name ] r o l l= r e q u e s t. form [ r o l l ] u s e r= r o o t, password= 123, s q l= INSERT INTO t e s t ( name, r o l l ) v a l u e s ( {}, {} ). f o r m a t ( name, r o l l ) c u r. e x e c u t e ( s q l ) msg= D at a Has Been S t o r e d r e t u r n r e n d e r t e m p l a t e ( message. html, msg= msg ) e x c e p t : r e t u r n D a t a b a s e c o n n e c t i o n e r r o r 2) Make sure that the python file is outside the templates directory. Now type python s t o r e. py on the terminal. An address will be displayed on the terminal.

4 4 3) Enter the above address in a browser. Fill the name and roll number and hit submit. 3.4 Fetching the stored Data from the Database 1) Save the following code in a file called display.html. < t a b l e b o r d e r=1> < t h e a d> < t h>name</ t h> < t h>roll</ t h> </ t h e a d> {% f o r row i n rows %} < t r> < t d>{{ row [ 0 ]}}</ t d> < t d>{{ row [ 1 ]}}</ t d> </ t r> {% e n d f o r %} </ t a b l e> <p><a h r e f= / >Back To Home Page</ a></ p> <p><a h r e f= / u p d a t e > Update</ a></ p> 2) Save the following code in a file titled display.py. 3) d e f l i s t ( ) : u s e r= r o o t, password = 123, d a t a b a s e= T e s t ) # C o n n e c t i n g t o Database c u r. e x e c u t e ( S e l e c t from t e s t ) # T h i s query i s used t o f e t c h t h e Data from t h e Database rows=c u r. f e t c h a l l ( ) d i s p l a y. html, rows= rows ) # R e t u r n i n g d i s p l a y. html F i l e 4) Now open the terminal and type python d i s p l a y. py An address will be displayed. 5) Open this address in a browser. You can see all the Name and Roll No entries in the database. 3.5 Updating the Database 1) 2) Save the following code in a file with titled show.html. < t a b l e b o r d e r=1> < t d>name</ t d> < t d>roll</ t d> < t d>u p d a t e</ t d> {% f o r row i n rows %} < t r> <form a c t i o n= / t e s t u p d a t e method= POST > < t d>< i n p u t t y p e = t e x t name = name v a l u e ={{ row [ 0 ]}}></ t d> < t d>< i n p u t t y p e = t e x t name = r o l l v a l u e ={{ row [ 1 ]}}></ t d> < t d>< i n p u t t y p e = submit v a l u e = u p d a t e ></ t d> </ form> </ t r> {% e n d f o r %} </ t a b l e> 3) Save the following code in a file titled update.py.

5 5 4) d e f l i s t ( ) : u s e r= r o o t, password = 123, d a t a b a s e= T e s t ) # c o n n e c t i n g t o t h e d a t a b a s e c u r. e x e c u t e ( S e l e c t from t e s t ) # f e t c h i n g a l l t h e data from t e s t t a b l e. rows=c u r. f e t c h a l l ( ) show. html, rows= rows ) # r e t u r n i n g show. html f i l r o u t e ( / t e s t u p d a t e, methods =[ GET, POST ] ) d e f t e s t u p d a t e ( ) : u s e r= r o o t, password = 123, d a t a b a s e= T e s t ) name= r e q u e s t. form [ name ] r o l l= r e q u e s t. form [ r o l l ] p r i n t ( r o l l ) p r i n t ( name ) c u r. e x e c u t e ( UPDATE t e s t s e t r o l l= {} where name= {}. f o r m a t ( r o l l, name ) ) # Query f o r u p d a t i n g t h e data i n t e s t t a b l e. message. html, msg= Data u p d a t e d r o u t e ( /backhome ) d e f backhome ( ) : s t u d e n t. html ) # r e t u r i n g t o t h e main page a f t e r u p d a t i n g 5) Now open the terminal and run the update.py file. 6) Update whatever data you wish to and click the Update button. 7) Run display.py to verify that your data is indeed updated. 3.6 Linking all modules to create the Database application 1) Save the following code in a file called output.html. <p> o u t p u t :{{ msg}}</ p> <p><a h r e f= / >Home</ a> </ p> <p><a h r e f= / d i s p l a y > Show L i s t</ a></ p> <p><a h r e f= / u p d a t e > Update</ a></ p> 2) Save the following code in a file titled app.py d e f s t u d e n t ( ) : s t u d e n t. html r o u t e ( / a c t, methods = [ GET, POST ] ) d e f a c t ( ) : i f ( r e q u e s t. method == POST ) : t r y :

6 6 name= r e q u e s t. form [ name ] r o l l= r e q u e s t. form [ r o l l ] u s e r= r o o t, password= 123, s q l= INSERT INTO t e s t ( name, r o l l ) v a l u e s ( {}, {} ). f o r m a t ( name, r o l l ) c u r. e x e c u t e ( s q l ) r e t u r n r e n d e r t e m p l a t e ( o u t p u t. html, msg= D at a Has Been S t o r e d ) e x c e p t : r e t u r n D a t a b a s e c o n n e c t i o n e r r o r o u t e ( / d i s p l a y ) d e f d i s p l a y ( ) : u s e r= r o o t, password= 123, c u r. e x e c u t e ( S e l e c t from t e s t ) rows=cur. f e t c h a l l ( ) d i s p l a y. html, rows=rows r o u t e ( / u p d a t e ) d e f l i s t ( ) : u s e r= r o o t, password= 123, c u r. e x e c u t e ( S e l e c t from t e s t ) rows=cur. f e t c h a l l ( ) show. html, rows=rows ) r o o t, password= 123, name= r e q u e s t. form [ name ] r o l l= r e q u e s t. form [ r o l l ] p r i n t ( r o l l ) p r i n t ( name ) c u r. e x e c u t e ( UPDATE t e s t s e t r o l l= {} where name= {}. f o r m a t ( r o l l, name ) ) s t u d e n t. html, msg= Data u p d a t e d r o u t e ( /backhome ) d e f backhome ( ) : s t u d e n t. html ) 3) Run app.py 4) Start using your application. 5) Modify your application so that you may delete a r o u t e ( / t e s t u p d a t e, methods =[ GET, POST ] ) d e f t e s t u p d a t e ( ) : u s e r=