# Required

> Design-time validations and CacheMetadata behavior for required activity properties in UiPath Marketplace.

## Activity Creator

![Activity Creator interface showing required property settings](https://dev-assets.cms.uipath.com/assets/images/marketplace/marketplace-docs-image-34371-32c47679-33e7b986.webp)

## Generated Code

Design-time validations are generated in `CacheMetadata` for all required properties. This means a workflow will not run unless values are provided for these fields.

```
...

 #region Protected Methods
protected override void CacheMetadata(CodeActivityMetadata metadata)
{
  if (FirstNumber == null) metadata.AddValidationError(string.Format(Resources.ValidationValue_Error, nameof(FirstNumber)));
  if (SecondNumber == null) metadata.AddValidationError(string.Format(Resources.ValidationValue_Error, nameof(SecondNumber)));
  base.CacheMetadata(metadata);
}
...
```

## Effect in UiPath Studio

All required input properties are added to the designer automatically. If any are left empty, a validation error is shown in the top-right corner of the activity.

![UiPath Studio activity designer showing required input properties and validation error](https://dev-assets.cms.uipath.com/assets/images/marketplace/marketplace-docs-image-34043-d4ac75c7-9798c9e2.webp)