Promptles
Data & Transformation

Validation

beginner

Definition

Checking that data meets expected rules before using it. Validation is a safety gate: it catches typos, missing fields, wrong types, and out-of-range values at the boundary, when data enters your system, rather than letting bad data cause mysterious failures later.

In the wild

Before saving a form submission, validate: Is the email a valid format? Is the age a positive number? Is the username between 3 and 20 characters? If any check fails, show an error instead of saving garbage to the database.

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