Accessing App Data in HarmonyOS Service Widgets

(1) Creating a Service Widget

After creating an ArkTS-based widget, the project will generate the following widget-related files:

• Widget lifecycle management file (EntryFormAbility.ets)
• Widget UI file (WidgetCard.ets)
• Widget configuration file (form_config.json)

(2) Configuring module.json5

Reference documentation for fields:

"extensionAbilities": [
  {
    "name": "EntryFormAbility",
    "srcEntry": "./ets/entryformability/EntryFormAbility.ets",
    "label": "$string:EntryFormAbility_label",
    "description": "$string:EntryFormAbility_desc",
    "type": "form",
    "metadata": [
      {
        "name": "ohos.extension.form",
        "resource": "$profile:form_config"
      }
    ]
  }
]

(3) Widget-Specific Configuration

Configuration resides in resources/base/profile/form_config.json.
Reference documentation for fields:

(4) UI Development and Parameter Handling

Widget UI code is located in ets/widget/. Parameter reception logic:

let storageUpdateByMsg = new LocalStorage();

@Entry(storageUpdateByMsg)
@Component
struct WidgetCard {
  @LocalStorageProp('diffExamDay') diffExamDay: number = -1;
}

(5) Widget Lifecycle and Data Passing

• Initialization logic in EntryFormAbility.onAddForm (e.g., passing widget ID to WidgetCard)
• Updates handled in onUpdateForm hook

(6) Accessing App Data During Widget Initialization

6.1 Notifying App to Update Widget Data

postCardAction(this, {
  action: "call",
  abilityName: "EntryAbility",
  params: {
    method: "upDiffExamDay",
    formId: this.formId,
  },
});

Timing Issue Solution:
Monitor formId changes instead of using aboutToAppear():

@LocalStorageProp('formId') @Watch('updateFormId') formId:string = '';

updateFormId() {
  postCardAction(this, {
    action: 'call',
    abilityName: 'EntryAbility',
    params: {
      method: 'upDiffExamDay',
      formId: this.formId
    }
  });
}

6.2 App-Side Data Handling

In EntryAbility.onCreate:

onCreate(want: Want, launchParam: AbilityConstant.LaunchParam): void {
  this.callee.on('upDiffExamDay', upDiffExamDayCall);
}

const upDiffExamDayCall = (data: rpc.MessageSequence): MyParcelable => {
  let params: Record<string, string> = JSON.parse(data.readString());
  if (params.formId) {
    PreferencesUtil.putSync('formId', params.formId)
    const diffExamDay = UserCacheManager.getDiffExamDay();

    diffExamDay === -1 
      ? getHomePageData(params.formId) // Fetch data if unavailable
      : Utils.updateDiffExamDay(params.formId); // Update widget directly
  }
  return new MyParcelable(1, 'success');
};

Updating Widget Data:

// Import required modules
import { formBindingData, formProvider } from '@kit.FormKit';

updateDiffExamDay(formId: string) {
  const diffExamDay = UserCacheManager.getDiffExamDay();
  let formMsg = formBindingData.createFormBindingData({
    'diffExamDay': diffExamDay
  });

  formProvider.updateForm(formId, formMsg)
    .then(() => console.log('Update success'))
    .catch((error) => console.error('Update failed:', error));
}