Development of Application Event Logging

When to Use

The event logging function helps applications log various information generated during running.

Available APIs

JS application event logging APIs are provided by the hiAppEvent module.

APIs for Event Logging

API Return Value Description
write(string eventName, EventType type, object keyValues, AsyncCallback<void> callback): void void Logs application events in asynchronous mode. This method uses an asynchronous callback to return the result.
write(string eventName, EventType type, object keyValues): Promise<void> Promise<void> Logs application events in asynchronous mode. This method uses a promise to return the result.

When an asynchronous callback is used, the return value can be processed directly in the callback. When a promise is used, the return value can also be processed in the promise in a similar way. For details about the result codes, see [Event Verification Result Codes](hiappevent-overview.md#Event Verification Result Codes).

APIs for Event Logging Configuration

API Return Value Description
configure(ConfigOption config) boolean Sets the configuration options for application event logging.
The value true indicates that the operation is successful, and value false indicates the opposite.

How to Develop

In this example, an application event is logged after the application startup execution page is loaded.

  1. Create a JS application project. In the displayed Project window, choose entry > src > main > js > default > pages > index, and double-click index.js. Add the code to log the initial application event after page loading. The sample code is as follows:

    import hiAppEvent from '@ohos.hiAppEvent'

export default {
    data: {
        title: ""
    },
    onInit() {
        this.title = this.$t('strings.world');

        // 1. Callback mode
        hiAppEvent.write("start_event", hiAppEvent.EventType.BEHAVIOR, {"int_data":100, "str_data":"strValue"}, (err, value) => {
            if (err) {
                console.error(`failed to write event because ${err.code}`);
                return;
            }
            console.log(`success to write event: ${value}`);
        });

        // 2. Promise mode
        hiAppEvent.write("start_event", hiAppEvent.EventType.BEHAVIOR, {"int_data":100, "str_data":"strValue"})
            .then((value) => {
                console.log(`success to write event: ${value}`);
            }).catch((err) => {
                console.error(`failed to write event because ${err.code}`);
            });
 
        // 3. Set the application event logging switch.
        hiAppEvent.configure({
            disable: true
        });

        // 4. Set the maximum size of the event file storage directory. The default value is 10M.
        hiAppEvent.configure({
            maxStorage: '100M'
        });
    }
}

  2. Tap the run button on the application UI to run the project.

Samples

The following sample is provided to help you better understand how to develop the application event logging feature: