> ## Documentation Index > Fetch the complete documentation index at: https://docs.twenty.com/llms.txt > Use this file to discover all available pages before exploring further. # Validation Rules > Set conditions that records must meet before they can be saved. ## What Are Validation Rules? A validation rule is a condition that must be true before a record can be created or updated. If the condition is false, Twenty blocks the save and shows a message explaining what needs to change. Use rules to require information at the right time, such as an amount before an opportunity becomes a customer, or to prevent inconsistent values, such as an end date before a start date. > [!NOTE] > > Validation rules are available on the Organization plan. You need permission > to edit the data model to manage them. ## Create a Validation Rule 1. Go to **Settings → Data Model** and select the object you want to configure. 2. Open the **Settings** tab, find **Validation rules**, and click **Add rule**. 3. Give the rule a name and, optionally, a description to explain its purpose. 4. Write a **Condition**. Start typing a field name or function and select suggestions from the helper panel. 5. Under **Error**, enter a **Message** that tells people how to fix the record. Use **Show on** to attach it to a specific field or select **Whole record**. 6. Check the **Preview** to see how the condition behaves on existing records. 7. Click **Activate** to start enforcing the rule. New rules stay inactive until you activate them. A rule needs a name, a valid condition, and an error message before it can be activated. ### Preview Your Rule The preview uses up to three recent records from the selected object. Use the arrows to move between them and inspect the values used by the condition. | Status | Meaning | | - | - | | **Valid** | The record meets the condition. | | **Blocked** | The record fails the condition. The preview also shows your error message. | | **Error** | The condition could not be evaluated. Check the error details and adjust the expression. | Previewing a rule does not change any records. If the object has no records yet, create a few to try the preview. ## Write a Condition Write the condition that allows a save. For example, `employees > 0` allows a company to be saved only when its employee count is greater than zero. Use field names such as `employees`, rather than display labels such as **Employees**. Selecting a field from the helper inserts the correct reference. | Syntax | Use | | - | - | | `==`, `!=`, `<`, `<=`, `>`, `>=` | Compare values. | | `and`, `or`, `not` | Combine or negate conditions. | | `+`, `-`, `*`, `/` | Calculate values. | | `stage in ['NEW', 'CUSTOMER']` | Check whether a value is in a list. | | `true`, `false` | Compare boolean fields. | | `now` | Use the date and time of the save. | Put text in single or double quotes and use parentheses to group conditions. Use `and` and `or` rather than `&&` and `||`. ### Check for Missing Values | Function | Use | | - | - | | `isEmpty(value)` | Check for a missing value, empty text, an empty list, or an empty composite field. | | `isDefined(value)` | Check whether a value is set. Empty text still counts as defined. | | `isNonEmptyString(value)` | Check that a value is text with at least one character. | | `includes(listOrText, value)` | Check whether a list contains a value or text contains a substring. Text matching is case-sensitive. | | `arrayLength(list)` | Get the number of items in a list. | To make a field required, use `not isEmpty(fieldName)`. This also works for composite fields such as emails and addresses. ### Reference Composite and Related Fields Use a dot to read part of a composite field, such as `name.firstName` or `amount.amountMicros`. You can also read a field through a many-to-one relation, such as `company.name` on a person. Select fields from the helper to find the available paths. Currency amounts are stored in micros: one currency unit equals `1000000` micros. For example, `amount.amountMicros >= 100000000` requires an amount of at least 100 in the record's currency. For select fields, compare the stored option value, such as `'CUSTOMER'`, rather than its display label. Check the helper examples for the values available on your field. ## Example Rules Adapt the field names and option values to your data model. The `startDate`, `endDate`, and `tags` fields below are examples of custom fields. | Goal | Condition | Suggested error message | | - | - | - | | Require a company name | `not isEmpty(name)` | Enter a company name. | | Require a positive amount when an opportunity reaches Customer | `stage != 'CUSTOMER' or amount.amountMicros > 0` | Enter an amount greater than zero before moving this opportunity to Customer. | | Require a person to be linked to a company | `isDefined(company)` | Select a company for this person. | | Require an end date to be on or after the start date | `isDefined(startDate) and isDefined(endDate) and endDate >= startDate` | Enter a start date and an end date on or after it. | | Require at least one tag | `arrayLength(tags) > 0` | Add at least one tag. | The opportunity example uses `or` to make the amount requirement conditional: other stages can be saved without an amount. ## When Rules Are Checked Active rules are checked when records are created or updated, including changes made through the API, imports, and workflows. A record must pass all active rules for its object to be saved. Activating a rule does not change existing records. A record that fails the new condition must be corrected the next time it is saved. A condition that reads a related record is evaluated when the record the rule belongs to is saved. Editing the related record alone does not recheck it. ## Edit, Disable, or Delete a Rule Return to **Settings → Data Model → your object → Settings → Validation rules**, then click the rule. * **Edit:** Update the condition or message, check the preview, and click **Save**. For an inactive rule, this button is **Activate**. * **Disable:** In **Danger zone**, click **Disable** to stop enforcing the rule while keeping its configuration. Click **Enable** to enforce it again. * **Delete:** In **Danger zone**, click **Delete** and confirm to permanently remove the rule. Existing records are not changed. Deactivating or deleting a field used in a condition also deactivates the rules that read it. Review those rules before enabling them again. To define validation rules in an app, see the [developer guide](https://docs.twenty.com/developers/extend/apps/data/validation-rules.md). This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.