> ## Documentation Index
> Fetch the complete documentation index at: https://docs.hotglue.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Custom Credential Validation

> Specify custom validation logic for credential input in the widget.

The `credentialsFormValidator` option allows developers to inject a custom asynchronous validation callback into the widget.

This callback will be called when the tenant submits their credentials in the widget. If the custom validator returns an `errorMessage`, it will be displayed to the tenant.

## Syntax

```typescript theme={null}
credentialsFormValidator?: (
  oldConfig: TConfig,
  newConfig: TConfig,
  availableEntity: Record<string, unknown>,
  flowId: string,
  tenantId: string
) => Promise<{ errorMessage?: string; success: boolean }>;
```

## Parameters

* `oldConfig`: The current configuration settings before the tenant's update.
* `newConfig`: The updated configuration settings after the tenant's modification.
* `availableEntity`: The availableSource, availableTarget, or availableConnector that they are attempting linking ot
* `flowId`
* `tenantId`

## Example Usage

Below is a simple example demonstrating how to implement the `credentialsFormValidator`:

```typescript theme={null}
const myValidator = async (
  oldConfig,
  newConfig,
  availableEntity,
  flowId,
  tenantId
) => {
  if(newConfig.api_version >= 25) {
    return {
        success: false,
        errorMessage: "Invalid API version specified"
    }
  }
  return { success: true };
};

hotglue.open(
    "tenant-id",
    {
        credentialsFormValidator: myValidator
    }
)
```

This example checks if a specific field has changed and returns an error message if so, ensuring tenants are informed of exact validation issues in the widget.