Data Validation (AQA GCSE Computer Science)

Data Validation

What is data validation?

• Data validation is code which is used to check that an input from a user is acceptable and that it matches the requirements of the program

• There are 5 main categories of validation which can be carried out on fields and data types, these are

  • Length check

  • Type check

  • Range check

  • Presence check

  • Format check

• There can be occasions where more than one type of validation will be used on a field

• An example of this could be a password field which could have a length, presence and type check on it

Length check

• Checks the length of a string

• An example is ensuring that a password is 8 or more characters in length

• Code example

password_length = len(password)

while password_length < 8:
   password = input("Enter a password which is 8 or more characters")

Type check

• Check the data type of a field

• An example is checking a user's age has been entered as an integer, without creating an integer input

• Code example

age = input("Enter your age")

while age.isdigit() == False:
    print("enter a number")
    age = input("Enter your age as a number")

Range check

• Ensures the data entered as a number falls within a particular range

• An example is checking a user's age has been entered and falls between the digits of 0-100

• Code example

age = int(input("Enter your age"))

while age < 0 or age > 100:
    age = int(input("Enter your age, ensure it is between 0-100"))

Presence check

• Looks to see if any data has been entered in a field

• An example is checking that a user has entered a name when registering for a website

• Code example

name = input("Enter your name")

while name == "":
     name = input("You must enter your name here")

Format check

• Ensures that the data has been entered in the correct format

• An example would be ensuring that an email includes the @ symbol and a full stop (.)

• Code example

email = input("Enter your email address")

while "@" not in email or "." not in email:
    email = input("Please enter a valid email address")