User can make request using URL and
send data to application by submitting form in a view which is handled
by controller. However, a very important question that is not addressed is how
to ensure whether the data submitted by the user is valid or not. The most
important task to develop software include validation logic which ensures that
data received from user is valid or not i.e. the application will work with it
or not. The important task is also challenging for developers as they do not
only ensure the data can be analyzed for validity but provide timely feedback
to users which help to fix any invalid data and re-submit it again.
The Validation logic can be implemented
not only in client browser to provide immediate feedback to users but in server
as server can examine data using complex business rules. Another reason of
implementing validation logic in server is, we never be completely sure that
the incoming data (from network) is safe.
ASP.NET MVC has lot of built-in
mechanism to implement client and server validation and to provide feedback to
users. It will be used in the application to validate input from the users. For
example, when we send message to pet owner or create new pet profile.
Validation Workflow
It is very important to understand that
how validation works in order to provide user with best experience while ensuring
integrity of the application.
Validation happen in two
places: 1st in client browser and second at server. The steps in validation
work flow are given below (see Figure 1):
1. In client browser when user
submits data:
• Verifies that the all
required information is present or not.
• Verifies that data format
is correct or not. For example, verifies that data sent in e-mail
address field is well
formatted, we must check that the form of e-mail address (name followed by
symbol @ and followed by another name and end with a dot and more than two
characters).
• Verifies data types as well
(For example, a date field has valid date or not).
• If anything is wrong at
this point then the user will be given immediate feedback how to
correct the problem and
information will not be sent to the server. So, the user can resubmit the
request with corrections.
2. All client side validation
test succeeded then the data will be sent to the server.
3. At server, second round of
validation will be performed to enforce business rule and ensure that request
is not an attack.
• If there is any error then
the request will not be processed and information about error will be sent back
to browser. So that, user can make the necessary corrections.
4. Once all server side
validations test succeed then the request will be processed and result will be
produced (a view will be rendered or a file will be downloaded etc).
Figure 1. The validation process
workflow
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