Callouts and Field Validation

Overview

• What you’ll learn: How to implement real-time field-level validation and dynamic behavior using iDempiere callouts, including the IColumnCallout interface, CalloutEngine patterns, and practical code examples.
• Prerequisites: Lessons 1-12 (Beginner level), basic Java knowledge
• Estimated reading time: 25 minutes

Introduction

In the previous lesson, you learned how to build sophisticated UIs using the Application Dictionary alone. But there are limits to what declarative configuration can do. When a user changes a field value, you often need to respond in real time: auto-fill related fields, recalculate totals, validate business rules, or show warnings. This is exactly what callouts do.

A callout is a piece of Java code that iDempiere executes immediately when a user changes a field’s value in the UI. Unlike model validators (which fire during the save process), callouts fire instantly on field change, giving the user immediate feedback. This lesson teaches you how to write, register, and debug callouts.

Understanding Callouts

Callouts sit in the UI layer. When a user modifies a field value (by typing, selecting from a dropdown, or any other input), iDempiere checks whether that column has a callout registered. If it does, the callout code executes before the user moves to the next field.

Key Characteristics

• Triggered on field change — not on save, not on load, but on value change.
• Synchronous — the UI waits for the callout to complete before the user can continue.
• Can modify other fields — a callout on field A can set the values of fields B, C, and D.
• Can return error messages — returning a non-empty string displays an error and reverts the field change.
• UI-only — callouts do not fire during server-side imports, processes, or API calls. Only direct user interaction triggers them.

The IColumnCallout Interface

The modern way to implement callouts in iDempiere is through the IColumnCallout interface. This is the preferred approach for plugin-based development.

package org.idempiere.callout;

import java.util.Properties;
import org.adempiere.base.IColumnCallout;
import org.compiere.model.GridField;
import org.compiere.model.GridTab;

public class MyCallout implements IColumnCallout {

    @Override
    public String start(Properties ctx, int WindowNo,
                        GridTab mTab, GridField mField,
                        Object value, Object oldValue) {

        // ctx       - Application context (preferences, session info)
        // WindowNo  - Window number (for context variable scoping)
        // mTab      - The tab containing the changed field
        // mField    - The field that was changed
        // value     - The new value
        // oldValue  - The previous value

        // Return "" for success, or an error message string to revert
        return "";
    }
}

Each parameter serves a specific purpose:

• ctx (Properties) — The application context containing login info, preferences, and session-level variables. Access values with Env.getContext(ctx, WindowNo, "ColumnName").
• WindowNo (int) — Identifies the window instance. Important when the user has multiple windows open, as context variables are scoped by window number.
• mTab (GridTab) — Provides access to all fields in the current tab. Use mTab.setValue("ColumnName", newValue) to set other field values.
• mField (GridField) — The specific field that triggered the callout. Contains metadata like column name, display type, and current value.
• value (Object) — The new value the user entered. You must cast it to the appropriate type.
• oldValue (Object) — The value before the change. Useful for comparison logic.

The CalloutEngine Base Class

The CalloutEngine class is the traditional (pre-plugin) approach. It is still widely used in core iDempiere code. You extend CalloutEngine and register individual methods:

package org.compiere.model;

import java.util.Properties;
import org.compiere.model.CalloutEngine;
import org.compiere.model.GridField;
import org.compiere.model.GridTab;

public class CalloutMyTable extends CalloutEngine {

    /**
     * Called when C_BPartner_ID changes.
     * Auto-fills the contact and location fields.
     */
    public String bpartner(Properties ctx, int WindowNo,
                           GridTab mTab, GridField mField,
                           Object value) {

        if (isCalloutActive())  // Prevent recursive callouts
            return "";

        Integer bpartnerId = (Integer) value;
        if (bpartnerId == null || bpartnerId == 0)
            return "";

        // Look up the default contact for this business partner
        int contactId = DB.getSQLValue(null,
            "SELECT AD_User_ID FROM AD_User " +
            "WHERE C_BPartner_ID=? AND IsActive='Y' " +
            "ORDER BY IsDefaultContact DESC, AD_User_ID LIMIT 1",
            bpartnerId);

        if (contactId > 0) {
            mTab.setValue("AD_User_ID", contactId);
        }

        // Look up the default location
        int locationId = DB.getSQLValue(null,
            "SELECT C_BPartner_Location_ID FROM C_BPartner_Location " +
            "WHERE C_BPartner_ID=? AND IsActive='Y' " +
            "ORDER BY IsShipTo DESC, C_BPartner_Location_ID LIMIT 1",
            bpartnerId);

        if (locationId > 0) {
            mTab.setValue("C_BPartner_Location_ID", locationId);
        }

        return "";  // Success
    }
}

The isCalloutActive() Guard

Notice the isCalloutActive() check at the top. This is a critical pattern. When your callout sets a value on another field via mTab.setValue(), that field change can trigger its own callout, which might set another field, and so on — creating infinite recursion. The isCalloutActive() method returns true if a callout is already executing, preventing this chain.

Writing a Complete Callout: A Practical Example

Let us build a callout for a custom Sales Commission table. When the user selects a Product, the callout auto-fills the Commission Percentage from a rate table, and calculates the Commission Amount based on the line total.

package com.mycompany.callout;

import java.math.BigDecimal;
import java.util.Properties;
import org.adempiere.base.IColumnCallout;
import org.compiere.model.GridField;
import org.compiere.model.GridTab;
import org.compiere.util.DB;
import org.compiere.util.Env;

public class CalloutCommission implements IColumnCallout {

    @Override
    public String start(Properties ctx, int WindowNo,
                        GridTab mTab, GridField mField,
                        Object value, Object oldValue) {

        String columnName = mField.getColumnName();

        if ("M_Product_ID".equals(columnName)) {
            return product(ctx, WindowNo, mTab, value);
        }
        if ("LineNetAmt".equals(columnName)) {
            return calculateCommission(mTab);
        }

        return "";
    }

    private String product(Properties ctx, int WindowNo,
                           GridTab mTab, Object value) {

        Integer productId = (Integer) value;
        if (productId == null || productId == 0) {
            mTab.setValue("CommissionPct", Env.ZERO);
            mTab.setValue("CommissionAmt", Env.ZERO);
            return "";
        }

        // Look up the commission rate for this product
        BigDecimal rate = DB.getSQLValueBD(null,
            "SELECT CommissionPct FROM Z_CommissionRate " +
            "WHERE M_Product_ID=? AND IsActive='Y' " +
            "AND AD_Client_ID=?",
            productId,
            Env.getAD_Client_ID(ctx));

        if (rate == null) {
            rate = Env.ZERO;
        }

        mTab.setValue("CommissionPct", rate);

        // Recalculate commission amount
        return calculateCommission(mTab);
    }

    private String calculateCommission(GridTab mTab) {
        BigDecimal lineAmt = (BigDecimal) mTab.getValue("LineNetAmt");
        BigDecimal pct = (BigDecimal) mTab.getValue("CommissionPct");

        if (lineAmt == null) lineAmt = Env.ZERO;
        if (pct == null) pct = Env.ZERO;

        // Commission = LineNetAmt * CommissionPct / 100
        BigDecimal commission = lineAmt.multiply(pct)
            .divide(Env.ONEHUNDRED, 2, BigDecimal.ROUND_HALF_UP);

        mTab.setValue("CommissionAmt", commission);
        return "";
    }
}

Registering Callouts

Method 1: Application Dictionary Registration

For CalloutEngine-style callouts, set the Callout field on the AD_Column record:

-- In AD_Column.Callout field:
org.compiere.model.CalloutMyTable.bpartner

The format is fully.qualified.ClassName.methodName. You can chain multiple callouts by separating them with semicolons:

org.compiere.model.CalloutOrder.bPartner;org.compiere.model.CalloutOrder.bPartnerBill

Method 2: IColumnCalloutFactory (Plugin Approach)

For IColumnCallout implementations, you register a factory as an OSGi service. Create a factory class:

package com.mycompany.callout;

import java.util.ArrayList;
import java.util.List;
import org.adempiere.base.IColumnCallout;
import org.adempiere.base.IColumnCalloutFactory;
import org.compiere.model.GridField;
import org.compiere.model.GridTab;
import org.compiere.model.MColumn;

public class MyCalloutFactory implements IColumnCalloutFactory {

    @Override
    public IColumnCallout[] getColumnCallouts(String tableName,
                                               String columnName) {

        List<IColumnCallout> list = new ArrayList<>();

        if ("Z_Commission".equals(tableName)) {
            if ("M_Product_ID".equals(columnName)
                || "LineNetAmt".equals(columnName)) {
                list.add(new CalloutCommission());
            }
        }

        return list.toArray(new IColumnCallout[0]);
    }
}

Then register it in your plugin’s OSGI-INF component descriptor XML or via annotations:

<?xml version="1.0" encoding="UTF-8"?>
<scr:component xmlns:scr="http://www.osgi.org/xmlns/scr/v1.1.0"
    name="com.mycompany.callout.factory">
    <implementation class="com.mycompany.callout.MyCalloutFactory"/>
    <service>
        <provide interface="org.adempiere.base.IColumnCalloutFactory"/>
    </service>
</scr:component>

Callout vs Model Validator: When to Use Which

This is one of the most common questions for iDempiere developers. Here is a clear decision framework:

Rule of thumb: Use callouts for user experience (auto-fill, calculate, show/hide). Use model validators for data integrity (must always be enforced, regardless of how data enters the system). Often you will use both: a callout for immediate feedback and a model validator as the safety net.

Common Callout Patterns

Pattern 1: Auto-Fill Related Fields

// When user selects a product, fill in UOM and price
public String product(Properties ctx, int WindowNo,
                      GridTab mTab, GridField mField, Object value) {
    Integer productId = (Integer) value;
    if (productId == null || productId == 0) return "";

    MProduct product = MProduct.get(ctx, productId);
    mTab.setValue("C_UOM_ID", product.getC_UOM_ID());
    mTab.setValue("PriceList", product.getPriceList());
    return "";
}

Pattern 2: Calculate Derived Values

// When qty or price changes, recalculate line total
public String amt(Properties ctx, int WindowNo,
                  GridTab mTab, GridField mField, Object value) {
    BigDecimal qty = (BigDecimal) mTab.getValue("QtyOrdered");
    BigDecimal price = (BigDecimal) mTab.getValue("PriceActual");

    if (qty == null) qty = Env.ZERO;
    if (price == null) price = Env.ZERO;

    mTab.setValue("LineNetAmt", qty.multiply(price));
    return "";
}

Pattern 3: Validate and Reject

// Reject negative quantities
public String qty(Properties ctx, int WindowNo,
                  GridTab mTab, GridField mField, Object value) {
    BigDecimal qty = (BigDecimal) value;
    if (qty != null && qty.signum() < 0) {
        return "Quantity cannot be negative";  // Error: reverts field
    }
    return "";
}

Debugging Callouts

When a callout does not behave as expected, use these techniques:

• Logging: Use CLogger to add debug output: private static final CLogger log = CLogger.getCLogger(MyCallout.class); then log.fine("Callout fired for product: " + value);
• Eclipse Debugger: Set breakpoints in your callout code and run iDempiere from Eclipse in debug mode. The debugger pauses execution when the callout fires.
• Check Registration: Verify the callout is registered on the correct column. A common mistake is registering on the wrong table or column name.
• Check isCalloutActive(): If your callout appears to not fire, another callout might be suppressing it via the active flag.
• Null Checks: Always handle null values. Users can clear a field, sending null as the new value.

GridTab and GridField Access

The GridTab and GridField objects provide rich access to the current UI state:

// GridTab: Access any field in the current tab
Object val = mTab.getValue("ColumnName");           // Get current value
mTab.setValue("ColumnName", newValue);               // Set a value
int recordId = mTab.getRecord_ID();                  // Current record ID
boolean isNew = mTab.isNew();                        // Is this a new record?

// GridField: Metadata about the changed field
String colName = mField.getColumnName();             // Column name
int displayType = mField.getDisplayType();           // Display type
boolean isMandatory = mField.isMandatory(false);     // Is it mandatory?
String header = mField.getHeader();                  // Field label

Key Takeaways

• Callouts fire on UI field change, providing immediate feedback to users.
• The IColumnCallout interface is the modern approach; CalloutEngine is the traditional approach.
• Always use isCalloutActive() guards in CalloutEngine to prevent infinite recursion.
• Register callouts via AD_Column.Callout (traditional) or IColumnCalloutFactory (plugin).
• Use callouts for UX improvements (auto-fill, calculate), use model validators for data integrity enforcement.
• Callouts are UI-only — they do not fire during imports, processes, or API calls.
• Return an empty string for success, or an error message to revert the field change.

What’s Next

In Lesson 15, you will learn about Workflow Management — how to configure document processing workflows, build approval chains, and automate business operations using iDempiere’s built-in workflow engine.

package org.idempiere.callout;

import java.util.Properties;
import org.adempiere.base.IColumnCallout;
import org.compiere.model.GridField;
import org.compiere.model.GridTab;

public class MyCallout implements IColumnCallout {

    @Override
    public String start(Properties ctx, int WindowNo,
                        GridTab mTab, GridField mField,
                        Object value, Object oldValue) {

        // ctx       - 應用程式上下文（偏好設定、工作階段資訊）
        // WindowNo  - 視窗編號（用於上下文變數範圍）
        // mTab      - 包含已更改欄位的頁籤
        // mField    - 已更改的欄位
        // value     - 新值
        // oldValue  - 先前的值

        // 成功返回 ""，或返回錯誤訊息字串以還原
        return "";
    }
}

package org.compiere.model;

import java.util.Properties;
import org.compiere.model.CalloutEngine;
import org.compiere.model.GridField;
import org.compiere.model.GridTab;

public class CalloutMyTable extends CalloutEngine {

    /**
     * 當 C_BPartner_ID 更改時呼叫。
     * 自動填入聯絡人和地址欄位。
     */
    public String bpartner(Properties ctx, int WindowNo,
                           GridTab mTab, GridField mField,
                           Object value) {

        if (isCalloutActive())  // 防止遞迴 Callout
            return "";

        Integer bpartnerId = (Integer) value;
        if (bpartnerId == null || bpartnerId == 0)
            return "";

        // 查詢此業務夥伴的預設聯絡人
        int contactId = DB.getSQLValue(null,
            "SELECT AD_User_ID FROM AD_User " +
            "WHERE C_BPartner_ID=? AND IsActive='Y' " +
            "ORDER BY IsDefaultContact DESC, AD_User_ID LIMIT 1",
            bpartnerId);

        if (contactId > 0) {
            mTab.setValue("AD_User_ID", contactId);
        }

        // 查詢預設地址
        int locationId = DB.getSQLValue(null,
            "SELECT C_BPartner_Location_ID FROM C_BPartner_Location " +
            "WHERE C_BPartner_ID=? AND IsActive='Y' " +
            "ORDER BY IsShipTo DESC, C_BPartner_Location_ID LIMIT 1",
            bpartnerId);

        if (locationId > 0) {
            mTab.setValue("C_BPartner_Location_ID", locationId);
        }

        return "";  // 成功
    }
}

package com.mycompany.callout;

import java.math.BigDecimal;
import java.util.Properties;
import org.adempiere.base.IColumnCallout;
import org.compiere.model.GridField;
import org.compiere.model.GridTab;
import org.compiere.util.DB;
import org.compiere.util.Env;

public class CalloutCommission implements IColumnCallout {

    @Override
    public String start(Properties ctx, int WindowNo,
                        GridTab mTab, GridField mField,
                        Object value, Object oldValue) {

        String columnName = mField.getColumnName();

        if ("M_Product_ID".equals(columnName)) {
            return product(ctx, WindowNo, mTab, value);
        }
        if ("LineNetAmt".equals(columnName)) {
            return calculateCommission(mTab);
        }

        return "";
    }

    private String product(Properties ctx, int WindowNo,
                           GridTab mTab, Object value) {

        Integer productId = (Integer) value;
        if (productId == null || productId == 0) {
            mTab.setValue("CommissionPct", Env.ZERO);
            mTab.setValue("CommissionAmt", Env.ZERO);
            return "";
        }

        // 查詢此產品的佣金費率
        BigDecimal rate = DB.getSQLValueBD(null,
            "SELECT CommissionPct FROM Z_CommissionRate " +
            "WHERE M_Product_ID=? AND IsActive='Y' " +
            "AND AD_Client_ID=?",
            productId,
            Env.getAD_Client_ID(ctx));

        if (rate == null) {
            rate = Env.ZERO;
        }

        mTab.setValue("CommissionPct", rate);

        // 重新計算佣金金額
        return calculateCommission(mTab);
    }

    private String calculateCommission(GridTab mTab) {
        BigDecimal lineAmt = (BigDecimal) mTab.getValue("LineNetAmt");
        BigDecimal pct = (BigDecimal) mTab.getValue("CommissionPct");

        if (lineAmt == null) lineAmt = Env.ZERO;
        if (pct == null) pct = Env.ZERO;

        // 佣金 = LineNetAmt * CommissionPct / 100
        BigDecimal commission = lineAmt.multiply(pct)
            .divide(Env.ONEHUNDRED, 2, BigDecimal.ROUND_HALF_UP);

        mTab.setValue("CommissionAmt", commission);
        return "";
    }
}

-- 在 AD_Column.Callout 欄位中：
org.compiere.model.CalloutMyTable.bpartner

org.compiere.model.CalloutOrder.bPartner;org.compiere.model.CalloutOrder.bPartnerBill

package com.mycompany.callout;

import java.util.ArrayList;
import java.util.List;
import org.adempiere.base.IColumnCallout;
import org.adempiere.base.IColumnCalloutFactory;
import org.compiere.model.GridField;
import org.compiere.model.GridTab;
import org.compiere.model.MColumn;

public class MyCalloutFactory implements IColumnCalloutFactory {

    @Override
    public IColumnCallout[] getColumnCallouts(String tableName,
                                               String columnName) {

        List<IColumnCallout> list = new ArrayList<>();

        if ("Z_Commission".equals(tableName)) {
            if ("M_Product_ID".equals(columnName)
                || "LineNetAmt".equals(columnName)) {
                list.add(new CalloutCommission());
            }
        }

        return list.toArray(new IColumnCallout[0]);
    }
}

<?xml version="1.0" encoding="UTF-8"?>
<scr:component xmlns:scr="http://www.osgi.org/xmlns/scr/v1.1.0"
    name="com.mycompany.callout.factory">
    <implementation class="com.mycompany.callout.MyCalloutFactory"/>
    <service>
        <provide interface="org.adempiere.base.IColumnCalloutFactory"/>
    </service>
</scr:component>

// 當使用者選擇產品時，填入計量單位和價格
public String product(Properties ctx, int WindowNo,
                      GridTab mTab, GridField mField, Object value) {
    Integer productId = (Integer) value;
    if (productId == null || productId == 0) return "";

    MProduct product = MProduct.get(ctx, productId);
    mTab.setValue("C_UOM_ID", product.getC_UOM_ID());
    mTab.setValue("PriceList", product.getPriceList());
    return "";
}

// 當數量或價格更改時，重新計算明細行合計
public String amt(Properties ctx, int WindowNo,
                  GridTab mTab, GridField mField, Object value) {
    BigDecimal qty = (BigDecimal) mTab.getValue("QtyOrdered");
    BigDecimal price = (BigDecimal) mTab.getValue("PriceActual");

    if (qty == null) qty = Env.ZERO;
    if (price == null) price = Env.ZERO;

    mTab.setValue("LineNetAmt", qty.multiply(price));
    return "";
}

// 拒絕負數數量
public String qty(Properties ctx, int WindowNo,
                  GridTab mTab, GridField mField, Object value) {
    BigDecimal qty = (BigDecimal) value;
    if (qty != null && qty.signum() < 0) {
        return "數量不能為負數";  // 錯誤：還原欄位
    }
    return "";
}

// GridTab：存取當前頁籤中的任何欄位
Object val = mTab.getValue("ColumnName");           // 取得當前值
mTab.setValue("ColumnName", newValue);               // 設定值
int recordId = mTab.getRecord_ID();                  // 當前記錄 ID
boolean isNew = mTab.isNew();                        // 這是新記錄嗎？

// GridField：已更改欄位的中繼資料
String colName = mField.getColumnName();             // 欄位名稱
int displayType = mField.getDisplayType();           // 顯示類型
boolean isMandatory = mField.isMandatory(false);     // 是否為必填？
String header = mField.getHeader();                  // 欄位標籤

package org.idempiere.callout;

import java.util.Properties;
import org.adempiere.base.IColumnCallout;
import org.compiere.model.GridField;
import org.compiere.model.GridTab;

public class MyCallout implements IColumnCallout {

    @Override
    public String start(Properties ctx, int WindowNo,
                        GridTab mTab, GridField mField,
                        Object value, Object oldValue) {

        // ctx       - アプリケーションコンテキスト（設定、セッション情報）
        // WindowNo  - ウィンドウ番号（コンテキスト変数のスコープ用）
        // mTab      - 変更されたフィールドを含むタブ
        // mField    - 変更されたフィールド
        // value     - 新しい値
        // oldValue  - 以前の値

        // 成功時は ""を返し、エラーメッセージ文字列を返すと元に戻す
        return "";
    }
}

package org.compiere.model;

import java.util.Properties;
import org.compiere.model.CalloutEngine;
import org.compiere.model.GridField;
import org.compiere.model.GridTab;

public class CalloutMyTable extends CalloutEngine {

    /**
     * C_BPartner_IDが変更されたときに呼び出されます。
     * 連絡先と住所フィールドを自動入力します。
     */
    public String bpartner(Properties ctx, int WindowNo,
                           GridTab mTab, GridField mField,
                           Object value) {

        if (isCalloutActive())  // 再帰的コールアウトを防止
            return "";

        Integer bpartnerId = (Integer) value;
        if (bpartnerId == null || bpartnerId == 0)
            return "";

        // この取引先のデフォルト連絡先を検索
        int contactId = DB.getSQLValue(null,
            "SELECT AD_User_ID FROM AD_User " +
            "WHERE C_BPartner_ID=? AND IsActive='Y' " +
            "ORDER BY IsDefaultContact DESC, AD_User_ID LIMIT 1",
            bpartnerId);

        if (contactId > 0) {
            mTab.setValue("AD_User_ID", contactId);
        }

        // デフォルト住所を検索
        int locationId = DB.getSQLValue(null,
            "SELECT C_BPartner_Location_ID FROM C_BPartner_Location " +
            "WHERE C_BPartner_ID=? AND IsActive='Y' " +
            "ORDER BY IsShipTo DESC, C_BPartner_Location_ID LIMIT 1",
            bpartnerId);

        if (locationId > 0) {
            mTab.setValue("C_BPartner_Location_ID", locationId);
        }

        return "";  // 成功
    }
}

package com.mycompany.callout;

import java.math.BigDecimal;
import java.util.Properties;
import org.adempiere.base.IColumnCallout;
import org.compiere.model.GridField;
import org.compiere.model.GridTab;
import org.compiere.util.DB;
import org.compiere.util.Env;

public class CalloutCommission implements IColumnCallout {

    @Override
    public String start(Properties ctx, int WindowNo,
                        GridTab mTab, GridField mField,
                        Object value, Object oldValue) {

        String columnName = mField.getColumnName();

        if ("M_Product_ID".equals(columnName)) {
            return product(ctx, WindowNo, mTab, value);
        }
        if ("LineNetAmt".equals(columnName)) {
            return calculateCommission(mTab);
        }

        return "";
    }

    private String product(Properties ctx, int WindowNo,
                           GridTab mTab, Object value) {

        Integer productId = (Integer) value;
        if (productId == null || productId == 0) {
            mTab.setValue("CommissionPct", Env.ZERO);
            mTab.setValue("CommissionAmt", Env.ZERO);
            return "";
        }

        // この製品の手数料率を検索
        BigDecimal rate = DB.getSQLValueBD(null,
            "SELECT CommissionPct FROM Z_CommissionRate " +
            "WHERE M_Product_ID=? AND IsActive='Y' " +
            "AND AD_Client_ID=?",
            productId,
            Env.getAD_Client_ID(ctx));

        if (rate == null) {
            rate = Env.ZERO;
        }

        mTab.setValue("CommissionPct", rate);

        // 手数料金額を再計算
        return calculateCommission(mTab);
    }

    private String calculateCommission(GridTab mTab) {
        BigDecimal lineAmt = (BigDecimal) mTab.getValue("LineNetAmt");
        BigDecimal pct = (BigDecimal) mTab.getValue("CommissionPct");

        if (lineAmt == null) lineAmt = Env.ZERO;
        if (pct == null) pct = Env.ZERO;

        // 手数料 = LineNetAmt * CommissionPct / 100
        BigDecimal commission = lineAmt.multiply(pct)
            .divide(Env.ONEHUNDRED, 2, BigDecimal.ROUND_HALF_UP);

        mTab.setValue("CommissionAmt", commission);
        return "";
    }
}

-- AD_Column.Calloutフィールドに：
org.compiere.model.CalloutMyTable.bpartner

org.compiere.model.CalloutOrder.bPartner;org.compiere.model.CalloutOrder.bPartnerBill

package com.mycompany.callout;

import java.util.ArrayList;
import java.util.List;
import org.adempiere.base.IColumnCallout;
import org.adempiere.base.IColumnCalloutFactory;
import org.compiere.model.GridField;
import org.compiere.model.GridTab;
import org.compiere.model.MColumn;

public class MyCalloutFactory implements IColumnCalloutFactory {

    @Override
    public IColumnCallout[] getColumnCallouts(String tableName,
                                               String columnName) {

        List<IColumnCallout> list = new ArrayList<>();

        if ("Z_Commission".equals(tableName)) {
            if ("M_Product_ID".equals(columnName)
                || "LineNetAmt".equals(columnName)) {
                list.add(new CalloutCommission());
            }
        }

        return list.toArray(new IColumnCallout[0]);
    }
}

<?xml version="1.0" encoding="UTF-8"?>
<scr:component xmlns:scr="http://www.osgi.org/xmlns/scr/v1.1.0"
    name="com.mycompany.callout.factory">
    <implementation class="com.mycompany.callout.MyCalloutFactory"/>
    <service>
        <provide interface="org.adempiere.base.IColumnCalloutFactory"/>
    </service>
</scr:component>

// ユーザーが製品を選択したら、UOMと価格を入力
public String product(Properties ctx, int WindowNo,
                      GridTab mTab, GridField mField, Object value) {
    Integer productId = (Integer) value;
    if (productId == null || productId == 0) return "";

    MProduct product = MProduct.get(ctx, productId);
    mTab.setValue("C_UOM_ID", product.getC_UOM_ID());
    mTab.setValue("PriceList", product.getPriceList());
    return "";
}

// 数量または価格が変更されたら、明細行合計を再計算
public String amt(Properties ctx, int WindowNo,
                  GridTab mTab, GridField mField, Object value) {
    BigDecimal qty = (BigDecimal) mTab.getValue("QtyOrdered");
    BigDecimal price = (BigDecimal) mTab.getValue("PriceActual");

    if (qty == null) qty = Env.ZERO;
    if (price == null) price = Env.ZERO;

    mTab.setValue("LineNetAmt", qty.multiply(price));
    return "";
}

// 負の数量を拒否
public String qty(Properties ctx, int WindowNo,
                  GridTab mTab, GridField mField, Object value) {
    BigDecimal qty = (BigDecimal) value;
    if (qty != null && qty.signum() < 0) {
        return "数量は負の値にできません";  // エラー：フィールドを元に戻す
    }
    return "";
}

// GridTab：現在のタブ内の任意のフィールドにアクセス
Object val = mTab.getValue("ColumnName");           // 現在の値を取得
mTab.setValue("ColumnName", newValue);               // 値を設定
int recordId = mTab.getRecord_ID();                  // 現在のレコードID
boolean isNew = mTab.isNew();                        // 新しいレコードか？

// GridField：変更されたフィールドのメタデータ
String colName = mField.getColumnName();             // カラム名
int displayType = mField.getDisplayType();           // 表示タイプ
boolean isMandatory = mField.isMandatory(false);     // 必須か？
String header = mField.getHeader();                  // フィールドラベル