js-apis-formextensioncontext.md

# FormExtensionContext

> ![icon-note.gif](public_sys-resources/icon-note.gif) **NOTE**
> The initial APIs of this module are supported since API version 8. Newly added APIs will be marked with a superscript to indicate their earliest API version.

Implements the context that provides the capabilities and APIs of **FormExtension**. This class is inherited from **ExtensionContext**.

## FormExtensionContext.updateForm

updateForm(formId: string, formBindingData: formBindingData.FormBindingData, callback: AsyncCallback\<void>): void

Updates a widget. This method uses a callback to return the result.

**System capability**: SystemCapability.Ability.Form

**Parameters**

  | Name         | Type                                                        | Mandatory| Description                                  |
  | --------------- | ------------------------------------------------------------ | ---- | -------------------------------------- |
  | formId          | string                                                       | Yes  | ID of the widget that requests to be updated.                    |
  | formBindingData | [formBindingData.FormBindingData](js-apis-formbindingdata.md#formbindingdata) | Yes  | New data of the widget.                        |
  | callback        | AsyncCallback\<void>                                         | Yes  | Callback used to return the result indicating whether the method is successfully called.|

**Example**

  ```js
  let obj2 = formBindingData.createFormBindingData({temperature:"22c", time:"22:00"});
  this.context.updateForm(formId, obj2, (data)=>{
      console.log('FormExtension context updateForm, data:' + data);
  });
  ```

## FormExtensionContext.updateForm

updateForm(formId: string, formBindingData: formBindingData.FormBindingData): Promise\<void>

Updates a widget. This method uses a promise to return the result.

**System capability**: SystemCapability.Ability.Form

**Parameters**

  | Name         | Type                                                        | Mandatory| Description              |
  | --------------- | ------------------------------------------------------------ | ---- | ------------------ |
  | formId          | string                                                       | Yes  | ID of the widget that requests to be updated.|
  | formBindingData | [formBindingData.FormBindingData](js-apis-formbindingdata.md#formbindingdata) | Yes  | New data of the widget.    |

**Return value**

  | Type          | Description                             |
  | -------------- | --------------------------------- |
  | Promise\<void> | Promise returned with the result indicating whether the method is successfully called.|

**Example**

  ```
  let obj2 = formBindingData.createFormBindingData({temperature:"22c", time:"22:00"});
  this.context.updateForm(formId, obj2)
      .then((data)=>{
          console.log('FormExtension context updateForm, data:' + data);
      }).catch((error) => {
      console.error('Operation updateForm failed. Cause: ' + error);});
  ```