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Web Database Applications with PHP, and MySQL by David Lane, Hugh E. Williams

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Server-Side Validation

In this section, we introduce validation on the server. The techniques described here are typical of those that validate a <form> after the user has submitted data to the server. We show how to extend and integrate this approach further in Chapter 8 so that the batch errors are reported as part of the customer <form>, and we show the completed customer entry <form> and validation in Chapter 10.

Case Study: Customer Validation in the Winestore

In this section, we show how to validate selected winestore customer <form> data, including examples of the validation checks required for mandatory fields, field lengths, and data types. Many functions—including the regular expression and string functions—are discussed in detail in Chapter 2.

Our system requirements in Chapter 1 note the following validation requirements:

  • A user must provide a surname, first name, one address line, a city, a state, a zip code, a country, a birth date, an email address, and a password.

  • The user may also optionally provide a middle initial, a title, two additional address lines, a state, a telephone number, and a fax number.

Testing whether mandatory fields have been entered is straightforward, and we have implemented this in our examples in Chapter 6. For example, to test if the user’s surname has been entered, use the following approach:

// Validate the Surname if (empty($formVars["surname"])) // the user's surname cannot be a null string $errorString .= "\n<br>The surname field cannot ...

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