## Overview
The Labii Column Addition widget is designed to perform calculations on numeric columns originating from a source record, defined by a ForeignKey widget. This powerful feature enables users to effortlessly manipulate and perform calculations on specified numeric data columns associated with interconnected records.
## Use case
1. Update the stock quantity after checkin/checkout.
## Configuration
To enable the widget's functionality, it requires the provision of options. Each option comprises the following two fields:
* **Source column** - To define the data source, select one of the ForeignKey columns.
* **Field Quantity** - Choose a quantity column to be updated. The value of the column have to be numeric.
* **Calculation** - How do you want to change the quantity value. Default to addition.
* Other configurations same as the [Number](https://docs.labii.com/widgets/column-widgets/form/text-inputs/number) widget.
### Examples:
```json
{
"column": {
"sid": "xxx",
"name": "source"
},
"quantity": {
"sid": "xxx",
"name": "quantity"
},
"calculation": "subtraction",
"format": {
"thousand": ","
},
"constraints": {
"min": 0
}
}
```
## Views
See the interface of the widget in the following views.
### **Readonly view**
Readonly view display the values of the column.
### **Edit view**
The Edit view is the interface that allows you to modify the value.
{% hint style="info" %}
The change of the value will trigger the addition/subtraction of the source column.
{% endhint %}
### **Form view**
The Form view is the field integrated into the add form for collecting values when creating a new record.
The Form view is same as the Edit view.
## Data
Each widget in Labii stores data in a unique manner; refer below to understand how data from this widget is stored.
### Data format
Numeric value.
### **Default value**
The Default Value field within the column allows you to specify the default value when a record is created.
Default value shall be a number.
### **Import value**
The Import Value is the value you need to include in your Excel table for it to be imported into Labii.
Import value shall be a number.
