# Transaction Item Filters
Transaction item filters are a powerful tool in Open Loyalty that allow you to **narrow down the list of products** included in a transaction before applying rules and effects. These filters work on the **line-item level** within a transaction - letting you isolate products based on attributes like category, price, quantity, brand, or custom values.
## How to Add a Transaction Item Filter
{% stepper %}
{% step %}
In the **Rules & Effects** step of campaign creation, click the **Transaction filters** tab.\
{% endstep %}
{% step %}
Select **Add first transaction filter**.\
{% endstep %}
{% step %}
Choose the filter type — for example:
* Item category
* Item SKU
* Item name
* Item price
* Item custom attribute
* Item brand
{% endstep %}
{% step %}
Define your condition or multiple conditions.
{% endstep %}
{% step %}
Save the filter. It will be saved under a label like `Scenario 1` (you can rename it for clarity).
{% endstep %}
{% endstepper %}
***
## How to Use Transaction Filters in Campaign Rules
Once you have defined a transaction filter, you can reference it in both **Conditions** and **Effects**:
### **In Conditions**
You can use the filter to define conditions such as:
* **Quantity of filtered transaction**
* **Value of filtered transaction**
For example, set a rule to apply only if:
> Quantity of filtered transaction in *Scenario 1* is greater than 3\
> Value of filtered transaction in *Scenario 1* is at least 100 PLN
This allows for precise rule targeting.
### **In Effects**
You can reference filtered items when defining custom effects using expressions like:
```javascript
agg(filter(transaction.items,'scenario_1')).sumBy('grossValue')
agg(filter(transaction.items,'scenario_1')).sumBy('qty')
```
These expressions:
* **Sum the gross value** or **quantity** of the items in the transaction that match the selected filter (`scenario_1`).
* Allow you to create advanced effects based on only a subset of items.
{% hint style="warning" %}
`scenario_1` is a dynamic identifier generated based on the filter name.
Always ensure the name you reference in your expression matches the transaction filter’s label.
{% endhint %}
For example, set a rule to reward based on the following criteria:
> Give 1 point for every currency unit (e.g., for every dollar) spent.
You can also limit how much value or quantity is counted from each matching transaction item using a **cap**.
```javascript
(filter(transaction.items,'scenario_1')).sumBy('grossValue', 1)
(filter(transaction.items,'scenario_1')).sumBy('qty', 1)
```
**Examples:**
* `agg(filter(transaction.items,'filter_name')).sumBy('grossValue', 100)`\
→ Sums up `grossValue` per item, but caps each one at 100
* `agg(filter(transaction.items,'filter_name')).sumBy('qty', 2)`\
→ Counts quantity but caps it at 2 units per item
Use this when you want to prevent unusually high item values or quantities from impacting campaign conditions disproportionately.
## Summary
Transaction item filters help you build smarter, more targeted campaigns by focusing only on specific products within a transaction. You can:
* Define them once and reuse them in multiple rule conditions or effects.
* Create precise campaign logic based on filtered item sets.
* Use them to ensure bonuses or effects only apply to relevant items.
