---
title: How to make a field required/not required based on a 'Yes' or 'No' selection
description: "In OFS-Flow, you can create validation to make a field mandatory only when a specific answer, like \"Yes,\" is chosen in a previous field. If \"No\" is selected, the field will remain optional. This is useful for forms where a \"Yes\" answer requires a mandatory comment or corrective action, but a \"No\" answer does not."
---
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# How to make a field required/not required based on a 'Yes' or 'No' selection
## In OFS-Flow, you can create validation to make a field mandatory only when a specific answer, like "Yes," is chosen in a previous field. If "No" is selected, the field will remain optional. This is useful for forms where a "Yes" answer requires a mandatory comment or corrective action, but a "No" answer does not.
#### What you'll build
- A selection field, e.g. **Did you run a job?**, with "Yes" and "No" options.
- A text field, e.g. **Field A**, that becomes mandatory only when "Yes" is selected.
#### **Step 1 — Open the form**
Navigate to your alert and open the **Form** tab.
#### **Step 2 — Open the Field Validation Rules tab**
Select **Field A** and go to the **Field Validation Rules** tab. The rules below are set on **Field A** and are processed in order, from top to bottom.
#### **Step 3 — Add the validation rules in order**
**Rule 1 — mark as Valid if "No" is selected:**
```
data["Did you run a job?"]=="no"
```
This checks the selection field first. If it's "No", **Field A** is marked valid even if it's empty, and no further rules run for this field. Click **Valid** to set the status, colour, and a message.
**Rule 2 — mark as Valid if "Yes" is selected and the field is filled:**
```
(data["Did you run a job?"]=="yes")&&(data["Field A"]!="")
```
This only runs if Rule 1 was false, meaning "Yes" was selected. It marks the field valid only if the operator has entered text. Click **Valid** to set the status, colour, and a message.
**Rule 3 — catch-all, mark as Invalid:**
```
1==1
```
This is only reached if the first two rules fail — meaning "Yes" was selected but **Field A** was left empty.
- **Mark form as:** Invalid (or Error, to prevent submission).
- **With message:** "This field is required when 'Yes' is selected."
---
#### **Test it**
Select "No" and leave **Field A** empty — it should pass. Select "Yes" and leave **Field A** empty — it should fail with your message. Select "Yes" and fill in **Field A** — it should pass.
**Rule 1:**
****
**Rule 2:**
****
**Rule 3:** Mark as INVALID (Catch-all).
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