# Event Tracking

The Hackle SDK provides a feature to send user events to Hackle.

By using this feature at every point where a change in user behavior occurs, you can obtain meaningful data about user behavior and perform user behavior analysis with the collected data.

{% hint style="info" %}
You can check sent events in the [Event Management](https://dashboard.hackle.io/event-management) menu on the Dashboard. It generally takes up to \~60 seconds for events to appear on the Dashboard after being sent.
{% endhint %}

## track

Pass the **Event Key** to the `track()` method to send a user event.

<table><thead><tr><th width="150">Parameter</th><th width="120">Type</th><th width="110">Required</th><th>Constraints</th></tr></thead><tbody><tr><td>Event name (key)</td><td><code>string</code></td><td>Required</td><td>Maximum 128 characters.</td></tr></tbody></table>

#### Example

Assume you have defined an Event Key called `purchase` to collect an event when a user taps the purchase button.

```dart
import "package:hackle/hackle.dart";

/* Example 1: Send event key only */
HackleApp.track(HackleEvent.builder("purchase").build());
```

### Property

The Hackle SDK supports adding properties to an Event object.

* A property must be sent as a key-value pair consisting of a Property Key and a Property Value.
* You can add a maximum of 64 properties per event object.

<table><thead><tr><th width="133.04296875">Category</th><th width="127.60546875">Type</th><th>Constraints</th></tr></thead><tbody><tr><td>Property Key</td><td><code>string</code></td><td><ul><li>Character limit is 128 characters.</li><li>Case-insensitive.</li><li>For example, AGE and age are recognized as the same Property Key.</li></ul></td></tr><tr><td>Property Value</td><td><code>boolean</code>, <code>string</code>, <code>number</code>, <code>array</code></td><td><ul><li>For string type, the character limit is 1024 characters.</li><li>String type is case-sensitive.</li><li>For example, APPLE and apple are recognized as different Property Values.</li><li>For number type, up to 15 integer digits and up to 6 decimal places are supported.</li></ul></td></tr></tbody></table>

#### Example

In the example below, three properties (`pay_method`, `discount_amount`, `is_discount`) have been added.

```dart
import "package:hackle/hackle.dart";

HackleEvent event = HackleEvent.builder("purchase")
  .property("pay_method", "CARD")
  .property("discount_amount", 800)
  .property("is_discount", true)
  .build();

HackleApp.track(event);
```


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