View source for Java-Business-Application/C2/Database-and-validation/English-timed

{| border = 1
|  Time 
|  Narration

|-
|  00:01
|  Welcome to the spoken-tutorial on''' Database and validation.'''

|-
| 00:06
|  In this tutorial we will learn to:

|-
| 00:08
| Interact with database

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| 00:10
| Validate the fields 

|-
| 00:12
|Here we are using

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| 00:13
| Ubuntu Version 12.04

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| 00:15
| Netbeans IDE 7.3

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| 00:19
| JDK 1.7

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| 00:21
| Firefox web-browser 21.0

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| 00:24
|You can use any web-browser of your choice.

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| 00:28
|To follow this tutorial you must have knowledge of

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| 00:31
| Basics of '''Java Servlets '''and '''JSPs'''
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| 00:35
| Connecting to '''MySQL Database '''  from '''Netbeans IDE'''

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| 00:39
| Creating '''database '''and '''tables'''

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| 00:42
|If not, for relevant tutorials please visit our website.

|-
| 00:47
|Now, let us go to '''Netbeans IDE.'''

|-
| 00:52
|  I have started the '''MySQL server.'''

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|  00:55
|  I have created a '''database ''' in it named  '''library.'''

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| 01:00
|  I have created a '''table '''in it named '''Users.'''

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|  01:04
|  I have already inserted some values into this table.

|-
|  01:08
|  I will show them now.

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| 01:10
|  For that, right click on '''Users '''and click on '''View Data.'''

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| 01:15
|Click on the '''Output '''button at the bottom.

|-
|  01:19
|  We can see that there are '''15 users '''here.

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| 01:23
|   We can see the '''FirstName, Surname, Age, Gender, Email, Username '''and '''Password. '''

|-
|  01:31
|  Now, let us load the '''JDBC''' driver that is '''Java Database Connectivity Driver.'''

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|  01:39
| For that, click on the '''Projects tab.'''

|-
|  01.42
|  Right click on '''Libraries''' and  Click on '''Add Library.'''

|-
| 01.46
|  Then click on '''MySQL JDBC Driver.'''

|-
|  01.50
|  And click on '''Add Library.'''

|-
|  01.53
|  This will load the '''JDBC Driver.'''

|-
|  01.56
|  Let us '''run '''the '''Project '''as we had done earlier.

|-
|  02.00
| Now,  type the '''username '''as '''arya '''and '''password '''as '''arya123*.'''

|-
|  02.06
|  Then click on '''Sign In.'''

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|  02.08
|  We can see the '''successGreeting '''page.

|-
|  02.12
|  Click on '''here '''to logout.

|-
|  02.15
|  Now, let us switch back to the '''IDE.'''

|-
|  02.17
|  We will go to '''GreetingServlet '''''dot '''''java.'''
|-
|  02.21
| Come to the '''doPost''' method

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|  02.23
|  First, we get the '''Username '''and '''Password '''from the '''request '''using '''getParameter method.'''

|-
|  02.31
|  Next we will see the code for '''JDBC connection.'''

|-
| 02.35
|  We have initialized the '''Connection object, PreparedStatement object '''and '''Resultset object '''to '''null.'''

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| 02.44
|  Then we '''register '''the '''driver '''in our '''program.'''

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|  02.48
|  Then we create a connection to the '''database.'''

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| 02.52
|  Then, we execute the '''prepareStatement method '''on the '''Connection object.'''

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| 02.58
| We give the query to get the '''user details '''from '''Users table.'''

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| 03.03
| We check if '''username '''and '''password '''is same as that which is entered in the form.

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|  03.09
|  Here, the question mark denotes each field in the database.

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| 03.15
|  To supply values in place of question mark, we execute the '''setString method.'''

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| 03.22
| We do this using the '''PreparedStatement object.'''

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|  03.26
|  Then we execute the '''executeQuery method '''on the '''Prepared statement''' object
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|03.33
|We store  the result in '''ResultSet''' object

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|03.37
|  For successful login, we display the '''successGreeting page.'''

|-
|  03.43
|  For this, we use the '''RequestDispatcher interface.'''

|-
|  03.48
|  We use the '''getRequestDispatcher method '''on the '''request '''to obtain the '''RequestDispatcher object.'''

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| 03.56
|  We then invoke the '''forward method '''on '''RequestDispatcher.''' object

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| 04.02
| In this way, we '''forward '''to '''successGreeting '''''dot '''''jsp.'''

|-
| 04.07
|Now switch back to the slides

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| 04.10
|Let us learn something about '''RequestDispatcher interface'''

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| 04.15
| This  interface provides the facility of dispatching  the '''request''' to another resouce

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| 04.22
| The resorce can be html, servlet, or jsp

|-
| 04.26
| Now let us come back to the IDE
|-
|  04.29
|  Let us come to '''successGreeting '''''dot '''''jsp.'''

|-
|  04.33
|  Here, we are displaying the success message '''You have successfully logged in.'''

|-
| 04:38
|  Now, come back to the '''browser.'''

|-
|  04.41
| Type a '''username '''and '''password '''that we have not included in the '''database.'''

|-
|  04.47
|  So, let me type '''abc '''as the '''username '''and '''abc123* '''as the '''password.'''

|-
| 04.56
|  Then click on '''Sign In.'''

|-
| 04.59
|  We can see that we get the '''error message '''on the same page itself.

|-
| 05.03
| '''Please correct the following error!!! Invalid username or password'''

|-
|  05.09
|  Now, let us see the code for this. 

|-
| 05.12
| So, Switch back to the '''IDE'''
|-
| 05.14
|  Go to '''GreetingServlet '''''dot '''''java.'''

|-
|  05.17
|  If the '''validation '''fails, then we should display the '''error messages.'''

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| 05.22
| First we have  initialized a '''List '''of '''errorMsgs.'''

|-
|  05.27
|  We set the variable '''errorMsgs '''into the '''request scope''' using '''setAttribute '''method'''.'''

|-
|05.35
|  Here, '''errorMsgs '''is the '''attribute name.'''

|-
| 05.39
|  We have initialized a '''String variable id '''to '''null.'''

|-
|  05.44
|  Then, we check if the '''user '''exists in the '''database.'''

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| 05.48
| If yes, we store the value in the variable '''id.'''

|-
|  05.53
|  Else, we add the error '''Invalid username or password '''to '''errorMsgs list.'''

|-
|  06.00
|  If the '''errorMsgs list '''is not empty, we display the '''error messages '''on '''index '''''dot '''''jsp.'''


|-
| 06.09
| So, we have to redirect to '''index '''''dot '''''jsp.'''


|-
| 06.13
| We have already seen how to redirect to another page using '''RequestDispatcher.'''

|-
|  06.20
|  Note that we have included this code inside the '''try catch block '''to handle '''exception '''scenarios.

|-
|  06.27
|  Now, we will see how to fetch '''errorMsgs '''variable in '''index '''''dot '''''jsp.'''

|-
|  06.34
|  First, we obtain the value of the '''attribute errorMsgs.'''

|-
| 06.38
| This is done using  '''getAttribute method '''on the '''request.'''

|-
|  06.44
|  Note that we have included the '''Java code '''within the opening tag  which is ''less than sign percentage sign ''and the ''closing tag percentage sign and greater than sign.''

|-
|  06.57
|  This block of code is known as '''scriptlet.'''

|-
| 07.02
| It contains '''Java code '''which is executed every time '''JSP '''is invoked.

|-
|  07.08
|  If the value of '''errorMsgs '''is not null, then we  display this message.

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| 07.15
| '''Please correct the following errors.'''

|-
| 07:18
|  Then we iterate through  list of  '''errorMsgs.'''

|-
|  07.23
|  We then display the '''error messages '''as a '''list.'''

|-
|  07.27
|  This is how we display the '''error messages '''on  '''index '''''dot '''''jsp.'''

|-
|  07.32
|  Now, let us see how to add a''' user''' into the '''database'''.

|-
|  07.37
|  Before adding a '''user '''into the '''database, '''we have to create a '''model '''for the '''User table.'''

|-
| 07.44
| Now, Let us see what a '''model '''is.

|-
|07.48
|  A '''model :'''

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| 07.49
|  Represents the underlying, logical structure of data in a '''software application.'''

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| 07.55
|  A '''Java class '''with '''attributes '''and '''setters '''and '''getters '''for them.

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| 08.00
|  In this way, we can consider '''model '''as a whole instead of the individual '''attributes.'''

|-
|  08.07
|  Now, Switch back to '''Netbeans IDE.'''

|-
| 08.11
| I have already created the model '''User '''''dot '''''java.'''

|-
| 08.16
|  Note that we have created this '''Java class '''inside the '''package org ''dot ''spokentutorial ''dot ''model.'''

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|08.24
|  We have the following '''attributes firstName, surname, age, gender, email, username, password.'''


|-
| 08.33
| We have initialized them to empty values.

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|  08.37
|  Then we have a '''parameterized constructor.'''

|-
|  08.41
|  We also have the '''default constructor.'''

|-
|  08.44
|  We define the '''getFirstName method.'''

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| 08.47
|  We also define the '''setFirstName method.'''

|-
|  08.51
|  Similary we define the '''set '''and '''get methods '''on each of the '''attributes.'''

|-
| 08.57
|  Come back to the '''browser'''.

|-
| 08.59
|  Now, let us click on '''here link '''to '''register.'''

|-
|  09.03
|  Type all the fields in the '''Registration Page.'''

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|  09.07
|  Then click on '''Add User.'''

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|  09.10
|  We get  '''Add User Success Page.'''

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|  09.14
|  We get  the message ''' Your request to add harshita was successful.'''

|-
|  09.20
|  Here '''harshita''' was the '''username''' that we have given 

|-
|  09.24
|  Now, let us see how this is done.

|-
|  09.28
|  So switch back to the '''IDE.'''

|-
|  09.30
|  Go to  '''AddUserServlet '''''dot '''''java.'''

|-
|  09.35
|  The steps are similar to that we had followed in '''GreetingServlet '''''dot '''''java.'''

|-
|  09.40
|  First we get the '''form parameters '''using the '''getParameter method.'''

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| 09.46
|  We initialize variable '''user '''as '''instance '''of '''User Model '''with individual '''attributes.'''

|-
|  09.53
|  We set the variable '''user '''into the '''request scope '''using '''setAttribute method.'''

|-
| 10.01
|  If there are no errors while filling  the '''form, '''we execute the query to  insert the values into the user tables.

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|  10.10
|  Then we forward to '''success user page'''

|-
|  10.15
|  Now, let us come to '''successUser '''''dot '''''jsp.'''

|-
|10.19  
|  First, we have imported '''User '''''dot '''''java.'''

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| 10.24
| This line of code is called '''directive '''in '''JSP.'''

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| 10.28
|  A '''JSP directive '''starts with ''opening tag less than sign percentage sign and at the rate sign ''and ends with ''closing tag percentage sign and greater than sign.''

|-
|  10.42
|  This one is a '''page directive.'''

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| 10.45
| The '''page directive '''contains a list of all imported '''packages.'''

|-
|  10.50
|  We get the value of the attribute '''user '''and store it as the '''User object.'''

|-
|  10.57
|  Then,We have the '''success message '''here.

|-
|  11.00
|  Here, we have retrieved the '''Username.'''

|-
| 11.04
| We have''' '''used the '''getUsername() method '''on the '''request object.'''

|-
|  11.09
|  We have done this using '''scriptlet tags.'''

|-
|  11.12
|  Now, let us come back to the browser.

|-
|  11.15
|  We will try to add a '''user '''already present in the database.

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|  11.20
|  So, I will add '''harshita '''again.

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| 11.24
|  We can see that we get the error message '''Please correct the following errors!!1  Duplicate entry 'harshita' for key username.'''

|-
|  11.33
| Now, Let us register for a user once again.

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|  11.37
|  Here, I have filled up the form now.

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|  11.40
|  I have created a mistake in the '''Age''' field.

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|  11.44
|  I have typed '''ab '''instead of a valid number.

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|  11.48
|  Now, click on '''Add User.'''

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|  11.51
|  We see we get the error message '''The age must be a positive integer.'''

|-
|  11.57
|  Now, let us see how this is done.


|-
| 12.00
| Switch back to the '''IDE.'''

|-
|  12.03
|  Open '''AddUserServlet '''''dot '''''java.'''

|-
|  12.08
|  Here also, we have created a '''list for errorMsgs.'''

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|  12.11
|  Then we set the variable '''errorMsgs '''into the '''request scope '''using '''setAttribute method.'''

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|  12.18
|  Then, we have declared '''ageUser '''of type '''integer''' and we have initialize it to -1

|-
|  12.26
|  Inside the '''try catch block '''we have used '''parseInt method.'''

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| 12.31
| This will return an integer, given a string representation of number as input.

|-
| 12.37
|  So here we validate that the '''age field''' contains a valid positive integer.

|-
| 12.44
| If the validation fails, then we add error message to '''errorMsgs list'''

|-
|  12.51
|  The age must be a positive integer.

|-
|  12.54
|  Similarly, we have to validate that all the other fields too have valid data.

|-
| 13.01
|  If the errorMsgs list is not empty, then we will display the '''errorMsgs '''on '''addUser '''''dot '''''jsp''' itself

|-
| 13.09
| We have already seen how to do this using the '''RequestDispatcher.'''

|-
|  13.15
|  Now, let us come to the '''addUser '''''dot '''''jsp.'''

|-
|  13.19
|  Here also, first we have imported '''User '''''dot '''''java.'''

|-
| 13.24
|  Inside the '''scriptlet tags '''we have created an '''object '''of type '''User.'''

|-
|  13.31
|  Then we get the value of the attribute '''errorMsgs '''using '''getAttribute method.'''

|-
|  13.38
|  We check if this value is equal to '''null.'''

|-
| 13.43
|  If it is not equal to null, then  we display the error message just as we had done for '''index '''''dot '''''jsp.'''

|-
| 13.51
|  If not, we will get the value of the '''attribute user from request '''using  '''User model.'''

|-
|  13.59
|  Then we have the '''form.'''

|-
|  14.01
|  The '''form tag '''has '''action '''as '''AddUserServlet '''and '''method '''as '''POST.'''

|-
|  14.07
|  The first field is '''First Name '''of '''input type '''as''' text ''','''name '''as '''firstName '''and '''value '''as '''user '''''dot '''''getFirstName.'''

|-
| 14.18
| Here, we are initializing the value of '''firstName '''to empty string.

|-
|  14.24
|  Similarly you have to do for other fields.

|-
| 14.28
|  We also have a  '''submit ''' button and value as  ''' Add User.'''


|-
|  14.33
|  This is how we validate the fields in '''addUser.jsp.'''

|-
|  14.38
|  You can try out different errors on the '''Add User page.'''

|-
|  14.42
|  Now let us see that the user '''harshita''' has been added to the '''database.'''

|-
|  14.49
| So come back to user table. We can see that harshita is added to the database.

|-
| 14.56
| In this tutorial we have learnt:

|-
| 14.58
|  Database connectivity and

|-
| 15.00
|  Field validation

|-
| 15.02
|  To know more about the spoken tutorial project, watch the video available at the following link.

|-
| 15.07
|  It summarizes the Spoken Tutorial Project

|-
| 15.11
|  If you do not have good bandwidth you can download and watch it

|-
|  15.15
|  The Spoken Tutorial Project Team

|-
| 15.17
|  Conducts workshops using spoken tutorials

|-
| 15.20
|  Gives certificates for those who pass an online test

|-
| 15.23
|  For more details please write to contact at spoken hyphen tutorial dot org

|-
| 15.29
|  Spoken Tutorial Project is a part of the Talk to a Teacher Project

|-
| 15.32
|  It is supported by the National Mission on Education through ICT, MHRD, Government of India

|-
| 15.38
|  More information on this mission is available at spoken-tutorial.org/NMEICT-intro

|-
| 15.48
|  The Library Management System has been contributed by a leading software MNC, through their Corporate Social Responsibility Programme.

|-
| 15.57
| They have also validated the content for this spoken tutorial.

|-
| 16.02
| This is Arya Ratish from IIT Bombay signing off.


Thank you for joining.

|}