# Context

The **Context** module provides context for abilities or applications. It allows access to application-specific resources.

> **NOTE**
>
>  - The initial APIs of this module are supported since API version 9. Newly added APIs will be marked with a superscript to indicate their earliest API version.
>  - The APIs of this module can be used only in the stage model.

## Modules to Import

```ts
import common from '@ohos.app.ability.common';
```

## Attributes

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

| Name         | Type    | Readable  | Writable  | Description     |
| ----------- | ------ | ---- | ---- | ------- |
| resourceManager     | resmgr.[ResourceManager](js-apis-resource-manager.md) | Yes   | No   | Object for resource management.  |
| applicationInfo | [ApplicationInfo](js-apis-bundle-ApplicationInfo.md) | Yes   | No   | Application information.|
| cacheDir | string | Yes   | No   | Cache directory.|
| tempDir | string | Yes   | No   | Temporary directory.|
| filesDir | string | Yes   | No   | File directory.|
| databaseDir | string | Yes   | No   | Database directory.|
| preferencesDir | string | Yes   | No   | Preferences directory.|
| bundleCodeDir | string | Yes   | No   | Bundle code directory. Do not access resource files by concatenating paths. Use the [resourceManager API](js-apis-resource-manager.md) instead.|
| distributedFilesDir | string | Yes   | No   | Distributed file directory.|
| eventHub | [EventHub](js-apis-inner-application-eventHub.md) | Yes   | No   | Event hub that implements event subscription, unsubscription, and triggering.|
| area | contextConstant.[AreaMode](js-apis-app-ability-contextConstant.md) | Yes   | No   | Encryption level of the directory.|

## Context.createBundleContext

createBundleContext(bundleName: string): Context;

Creates the context based on the bundle name.

**Required permissions**: ohos.permission.GET_BUNDLE_INFO_PRIVILEGED

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**System API**: This is a system API and cannot be called by third-party applications.

**Parameters**

| Name      | Type                    | Mandatory  | Description           |
| -------- | ---------------------- | ---- | ------------- |
| bundleName | string | Yes   | Bundle name.|

**Return value**

| Type| Description|
| -------- | -------- |
| Context | Context created.|

**Example**

```ts
let bundleContext: common.Context;
try {
    bundleContext = this.context.createBundleContext('com.example.test');
} catch (error) {
    console.error('createBundleContext failed, error.code: ${error.code}, error.message: ${error.message}');
}
```

## Context.createModuleContext

createModuleContext(moduleName: string): Context;

Creates the context based on the module name.

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**Parameters**

| Name      | Type                    | Mandatory  | Description           |
| -------- | ---------------------- | ---- | ------------- |
| moduleName | string | Yes   | Module name.|

**Return value**

| Type| Description|
| -------- | -------- |
| Context | Context created.|

**Example**

```ts
let moduleContext: common.Context;
try {
    moduleContext = this.context.createModuleContext('entry');
} catch (error) {
    console.error('createModuleContext failed, error.code: ${error.code}, error.message: ${error.message}');
}
```

## Context.createModuleContext

createModuleContext(bundleName: string, moduleName: string): Context;

Creates the context based on the bundle name and module name.

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**System API**: This is a system API and cannot be called by third-party applications.

**Parameters**

| Name      | Type                    | Mandatory  | Description           |
| -------- | ---------------------- | ---- | ------------- |
| bundleName | string | Yes   | Bundle name.|
| moduleName | string | Yes   | Module name.|

**Return value**

| Type| Description|
| -------- | -------- |
| Context | Context created.|

**Example**

```ts
let moduleContext: common.Context;
try {
    moduleContext = this.context.createModuleContext('com.example.test', 'entry');
} catch (error) {
    console.error('createModuleContext failed, error.code: ${error.code}, error.message: ${error.message}');
}
```

## Context.getApplicationContext

getApplicationContext(): ApplicationContext;

Obtains the context of this application.

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**Return value**

| Type| Description|
| -------- | -------- |
| [ApplicationContext](js-apis-inner-application-applicationContext.md) | Application context obtained.|

**Example**

```ts
let applicationContext: common.Context;
try {
    applicationContext = this.context.getApplicationContext();
} catch (error) {
    console.error('getApplicationContext failed, error.code: ${error.code}, error.message: ${error.message}');
}
```

## Context.getGroupDir<sup>10+</sup>

getGroupDir(dataGroupID: string): Promise\<string>;

Obtains the shared directory based on a group ID. This API uses a promise to return the result.

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**Parameters**

| Name      | Type                    | Mandatory  | Description           |
| -------- | ---------------------- | ---- | ------------- |
| dataGroupID | string | Yes   | Group ID, which is assigned by the system when an atomic service application project is created.|

**Return value**

| Type| Description|
| -------- | -------- |
| Promise\<string> | Promise used to return the result. If no shared directory exists, null is returned. Only the encryption level EL2 is supported.|

**Error codes**

For details about the error codes, see [Ability Error Codes](../errorcodes/errorcode-ability.md).

| ID| Error Message|
| ------- | -------- |
| 16000011 | The context does not exist. |

**Example**

```ts
let groupId = "1";
let getGroupDirContext: common.Context;
try {
  getGroupDirContext.getGroupDir(groupId).then(data => {
    console.log("getGroupDir result:" + data);
  })
} catch (error) {
  console.error('getGroupDirContext failed, error.code: ${error.code}, error.message: ${error.message}');
}
```

## Context.getGroupDir<sup>10+</sup>

getGroupDir(dataGroupID: string, callback: AsyncCallback\<string>);

Obtains the shared directory based on a group ID. This API uses an asynchronous callback to return the result.

**System capability**: SystemCapability.Ability.AbilityRuntime.Core

**Parameters**

| Name      | Type                    | Mandatory  | Description           |
| -------- | ---------------------- | ---- | ------------- |
| dataGroupID | string | Yes   | Group ID, which is assigned by the system when an atomic service application project is created.|
| callback | AsyncCallback\<string> | Yes   | Callback used to return the result. If no shared directory exists, null is returned. Only the encryption level EL2 is supported.|

**Error codes**

For details about the error codes, see [Ability Error Codes](../errorcodes/errorcode-ability.md).

| ID| Error Message|
| ------- | -------- |
| 16000011 | The context does not exist. |

**Example**

```ts
let getGroupDirContext: common.Context;

getGroupDirContext.getGroupDir("1", (err, data) => {
  if (err) {
    console.error('getGroupDir faile, err: ${JSON.stringify(err)}');
  } else {
    console.log('getGroupDir result is: ${JSON.stringify(data)}');
  }
});
```