# Validate at Least One Order Item When Submit

In the Order Management App, an order request **must contain at least one Order Item** before it can be submitted.\
To enforce this business rule, **validation logic** needs to be added so that the system prevents submission when no order item exists.

This section explains how to implement **one‑to‑many validation** by extending the existing Java customization and validating data **before the submit action completes**.

***

### Objective

By completing this section, you will learn how to:

* Validate one‑to‑many data relationships during submit
* Access child module data from Java customization
* Prevent form submission when validation fails
* Display user‑friendly error messages on the screen

***

### Step 1: Update Java Customization Class

Open the existing Java class:

```
com.manual.doc.order.java.OrderRequestRequesterInsertMode
```

Override the `validateResult()` method with the following implementation.

#### Java Validation Logic

```
@Override
public boolean validateResult() {

    logger.debug("========= Validate require at least 1 order request item ========");

    boolean result = true;
    String nextEntity = (String) request.getParameter("nextEntity");
    logger.debug("##### nextEntity ##### " + nextEntity);

        // Validate only when submitting the current entity
        if (nextEntity == null || "".equals(nextEntity)) {

        String entityID = (String) getRequest().getSession().getAttribute("entityID");
        EntityFormHandler formEntity =
        (EntityFormHandler) request.getSession().getAttribute(entityID + "_session");

        Vector vError = formEntity.getFormErrors();

        // Get Order Request Item module session
        MasterFormHandler formMaster =
        (MasterFormHandler) request.getSession().getAttribute("MD11784591_session");

        Vector vFormMaster = formMaster.getStoreActionList();
        logger.debug("##### vFormMaster ##### " + vFormMaster);

        // Validate at least one order item exists
        if (vFormMaster.size() == 0) {
        vError.add("Please add order item at least 1 item");
        result = false;
        }
    }
    return result;
}
```

This method checks whether the **Order Request Item module contains at least one record** before allowing submission.

***

### Step 2: Update Module Session ID

In the code above, replace:

```
MD11784591_session
```

with the **actual module ID** of module **“Order Request Item”** in entity\
\&#xNAN;**“Doc Order Request – Requester”**, followed by `_session`.

#### How to Find the Module ID

1. Open entity **Doc Order Request – Requester** in App Designer
2. Click **Edit** on module **Order Request Item**
3. Find the value of **Module ID**
4. Use that value in Java code as:

```
<ModuleID>_session
```

This ensures the validation checks the correct child module.

***

### Step 3: Deploy Updated Java Class

1. From the **ONEWEB workspace**, export `EafMasterEar.ear`
2. Deploy the updated EAR file to the server

The updated class

```
com.manual.doc.order.java.OrderRequestRequesterInsertMode
```

will now include the new validation logic.

***

### Step 4: Test the Validation

1. Log in to **FrontWeb** as a Requester user
2. Click menu:

   ```
   SETTING > Refresh Cache
   ```

   to reload the updated configuration
3. Open menu:

   ```
   DOC Order Request
   ```
4. Click **CREATE**
5. Try to **SUBMIT** the request **without adding any Order Item**

#### Expected Result

* The system prevents submission
* An error message is displayed:

  ```
  Please add order item at least 1 item
  ```

This confirms that validation is working correctly.

***

### Summary

In this section, you have:

* Implemented validation for one‑to‑many relationships
* Ensured at least one Order Item exists before submission
* Used Java customization to access child module data
* Prevented invalid business transactions from being processed

This validation strengthens **data integrity and business rule enforcement** in the **Order Management App (Web)** and demonstrates the power of **App Designer Customization combined with Java logic**.


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