# Jira Expression Condition & Validator

For advanced workflow scenarios, Workflow Building Blocks provides **Jira Expression Condition and Validator** that let you write fully custom expressions with **complete support for the Jira expression language**. Our **advanced editor** guides you with suggestions, syntax highlighting, validation, and real-time testing, making it easier to create complex rules correctly. These tools allow you to define precise conditions based on any combination of fields, statuses, or criteria, giving you full control over workflow transitions.

While the Jira Expression Validator is ideal for fully custom logic, we recommend using the [Ultimate Validator](/workflow-building-blocks-for-jira/conditions-validators/ultimate.md) for most use cases. It simplifies expression construction by providing a **visual, no-code UI**, so you can build advanced workflow conditions quickly and safely without needing to learn Jira expression syntax.

**Benefits of the Jira Expression Editor:**

* **Suggestions and auto-completion** – Helps you write expressions faster and reduces errors.
* **Syntax highlighting** – Makes it easier to read and understand complex expressions.
* **Real-time validation** – Detect errors immediately as you type.
* **Expression tester** – Validate your expressions on real issues directly in the configuration screen.
* **Custom field search by name** – Quickly find the IDs of the fields required by your expressions.

<figure><img src="/files/I5DYAa9MeDGuSJoZ00hX" alt=""><figcaption><p>Allow only users with the 'Developers' project role to create Story issues example</p></figcaption></figure>

### Jira expression<mark style="color:red;">\*</mark>

Expression is required. If the expression evaluates to false, the transition will not be executed, and the user will be prompted with a message to fix the errors.

Read more about writing expressions in [Introduction to Jira Expressions](/workflow-building-blocks-for-jira/writing-jira-expressions/introduction-to-jira-expressions.md).

{% hint style="info" %}
Jira expression must return the Boolean type (true or false). You won't be able to save configuration otherwise.
{% endhint %}

### Validation message

Override generic message displayed to the user when Jira expression evaluates to false.&#x20;

Read more about writing validation messages in [Writing validation messages](/workflow-building-blocks-for-jira/writing-jira-expressions/writing-validation-messages.md).

{% hint style="info" %}
Validation message expression must evaluate to String. You won't be able to save configuration otherwise.
{% endhint %}

Check out more examples on the [Jira Expressions Library: Examples & Use Cases](/workflow-building-blocks-for-jira/writing-jira-expressions/jira-expressions-library-examples-and-use-cases.md) page.


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