Database Reference
In-Depth Information
CHAPTER 12
Validating and Reformatting Data
12.0. Introduction
The previous chapter,
Chapter 11
, focuses on methods for moving data into and out of
MySQL. The present chapter is related in that it also covers data transfer issues, but here
the emphasis is on issues of datafile
content
rather than
structure
. For example, if you
don't know whether the values contained in a file are legal, preprocess it to check or
reformat them. Numeric values may need verification as lying within a specific range,
dates may need conversion to or from ISO format, and so forth.
The chapter deals with formatting and validation issues primarily within the context of
checking entire files, but many of the techniques discussed here can be applied in other
situations as well. Consider a web-based application that presents a form for a user to
fill in and then processes its contents to create a new row in the database. Web APIs
generally make form contents available as a set of already parsed discrete values, so the
application may not need to deal with record and column delimiters. On the other hand,
validation issues remain paramount. You really have no idea what kind of values a user
is sending your script, so it's important to check them. This chapter covers validation
extensively, and
Recipe 20.6
revisits the issue in web context.
For additional background on the material covered here, see the introduction to
Chap‐
ter 11
.
Source code for program fragments and scripts discussed in this chapter is located in
the
transfer
directory of the
recipes
distribution, with the exception that some utility
functions are contained in library files located in the
lib
directory.
