> For the complete documentation index, see [llms.txt](https://docs.fastn.ai/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.fastn.ai/tutorials-1/understanding-flow-types/how-to-set-up-a-configuration-flow-in-fastn/setting-up-field-level-validation-in-configuration-flows.md).

# Setting up Field-Level Validation in Configuration Flows

To enforce input validation at the field level within your configuration flows, follow these steps:

## **Steps to Enable Field Validation**

1. **Navigate to Your Configuration Flow**\
   Open the specific configuration flow where validation is needed.
2. **Select the Target Step**\
   Click on the step you want to apply validation to.
3. **Open Step Settings**\
   Click on the three-dot menu (`⋮`) associated with the step.

<figure><img src="/files/foYiMakhZCOWLGmqEG9h" alt=""><figcaption></figcaption></figure>

4. Click on **Configure**

<figure><img src="/files/GkMPIDwCvrZMmm72OJNv" alt=""><figcaption></figcaption></figure>

5. **Enable Submit Validation**\
   In the configuration pane, select the **Validation** tab and toggle **Enable Submit Validation**.

<figure><img src="/files/RKA884arzuSIrsT5O5Ac" alt=""><figcaption></figcaption></figure>

## **Validation Script: Empty Field and URL Format Check**

Paste the following JavaScript function into the validator field:

```js
jsCopyEditasync function validator(data = [
  {
    "Channel Name": "",
    "Webhook URL": ""
  }
]) {
  try {
    if (!data || (typeof data !== "object" && !Array.isArray(data))) {
      return { general: "Invalid data format" };
    }

    if (!Array.isArray(data)) {
      return {};
    }

    const errors = data.map((item) => {
      const entryErrors = {};

      const channelName = item["Channel Name"];
      const webhookUrl = item["Webhook URL"];

      if (!channelName || channelName.trim() === "") {
        entryErrors["Channel Name"] = "Channel Name is required";
      }

      if (!webhookUrl || webhookUrl.trim() === "") {
        entryErrors["Webhook URL"] = "Webhook URL is required";
      } else {
        try {
          new URL(webhookUrl); // throws if invalid
        } catch (_) {
          entryErrors["Webhook URL"] = "Invalid URL format";
        }
      }

      return Object.keys(entryErrors).length > 0 ? entryErrors : null;
    });

    return errors.filter((err) => err !== null).length > 0 ? errors : [];
  } catch (error) {
    return { general: "Failed to validate the data" };
  }
}
```

## **After You Add the Script**

* Click **Save.**
* **Redeploy** your configuration flow.

<figure><img src="/files/xfRNZo2nS0r1yHe1OmSM" alt=""><figcaption></figcaption></figure>

## **What This Validator Does?**

* Ensures both **"Channel Name"** and **"Webhook URL"** are not empty.
* Validates that **"Webhook URL"** is in a correct URL format.
* If either field fails, the form will block submission and show appropriate error messages.


---

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