# Validate This document explains how the *Validate* object is used to check whether your dataset meets certain conditions or rules before you use it further in your recipe. Think of it as a way to flag rows that don’t match expectations. ### Example Use Case Suppose you are working with a customer's table. Some customers don’t provide a fax number, but your business requires it for all active customers. You can configure the *Validate object* to identify these missing values.

1. In the toolbar, click on *Validate* and select the *Validate* option.

2. This will open the *Recipe Configuration – Validate* panel.

3. In this panel, you’ll configure the following options: * **Description:** Enter a meaningful name for the rule (e.g., “Missing Fax Validation”). * **Attach Rule to Field:** Select a field to associate the rule with. For example, the *Fax* column.

* **Show Message:** Provide a custom error or warning message that appears when a record fails the rule. * **Severity:** Choose whether a failed rule should be treated as an: * **Error:** The record is flagged and goes to the Invalid Output. * **Warning:** The record is flagged but still treated as valid * **Rule Condition**: Enter the expression for your rule by typing it directly or using the Expression Builder

with built-in functions, operators, and fields.

4. Once you’re done, click

*Apply.*

5. In the preview grid, records matching the "Missing Fax Validation" rule are validated. Conversely, records not matching the rule display an error, indicated by a red warning sign.

6. The records that fail to match the validation rule can be written and stored in a separate error log. Click [here](/dataprep/exporting-data.md#write-to-log-file) to learn how you can store erroneous records to a log file.

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