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Expo SQLite (legacy)

GitHub

npm

A library that provides access to a database that can be queried through a WebSQL-like API.

Android

iOS

expo-sqlite gives your app access to a database that can be queried through a WebSQL-like API. The database is persisted across restarts of your app.

Installation

Terminal

- npx expo install expo-sqlite

If you are installing this in an existing React Native app, start by installing expo in your project. Then, follow the additional instructions as mentioned by the library's README under "Installation in bare React Native projects" section.

Usage

To-do list app

An example to-do list app is available that uses this module for storage.

Importing an existing database

To open a new SQLite database using an existing .db file you already have, follow the steps below:

Install expo-file-system and expo-asset modules:

Terminal

- npx expo install expo-file-system expo-asset

Create a metro.config.js file at the root of your project with the following contents to include extra asset extensions:

const { getDefaultConfig } = require('expo/metro-config');

const defaultConfig = getDefaultConfig(__dirname);

defaultConfig.resolver.assetExts.push('db');

module.exports = defaultConfig;

Use the following function (or similar) to open your database:

import * as FileSystem from 'expo-file-system';
import * as SQLite from 'expo-sqlite/legacy';
import { Asset } from 'expo-asset';

async function openDatabase(pathToDatabaseFile: string): Promise<SQLite.SQLiteDatabase> {
  if (!(await FileSystem.getInfoAsync(FileSystem.documentDirectory + 'SQLite')).exists) {
    await FileSystem.makeDirectoryAsync(FileSystem.documentDirectory + 'SQLite');
  }
  const asset = await Asset.fromModule(require(pathToDatabaseFile)).downloadAsync();
  await FileSystem.copyAsync({
    from: asset.localUri,
    to: FileSystem.documentDirectory + 'SQLite/myDatabaseName.db',
  });
  return SQLite.openDatabase('myDatabaseName.db');
}

Executing statements with an async transaction

import * as SQLite from 'expo-sqlite/legacy';

const db = SQLite.openDatabase('dbName', version);

const readOnly = true;
await db.transactionAsync(async tx => {
  const result = await tx.executeSqlAsync('SELECT COUNT(*) FROM USERS', []);
  console.log('Count:', result.rows[0]['COUNT(*)']);
}, readOnly);

Executing statements outside of a transaction

You should use this kind of execution only when it is necessary. For instance, when code is a no-op within transactions. Example: PRAGMA foreign_keys = ON;.

import * as SQLite from 'expo-sqlite/legacy';

const db = SQLite.openDatabase('dbName', version);

await db.execAsync([{ sql: 'PRAGMA foreign_keys = ON;', args: [] }], false);
console.log('Foreign keys turned on');

API

import * as SQLite from 'expo-sqlite/legacy';

Classes

`ExpoSQLTransactionAsync`

Type: Class implements SQLTransactionAsync

Internal data structure for the async transaction API.

`SQLError`

SQLError Properties

`code`

Type: number

`message`

Type: string

`CONSTRAINT_ERR`

Type: number

`DATABASE_ERR`

Type: number

`QUOTA_ERR`

Type: number

`SYNTAX_ERR`

Type: number

`TIMEOUT_ERR`

Type: number

`TOO_LARGE_ERR`

Type: number

`UNKNOWN_ERR`

Type: number

`VERSION_ERR`

Type: number

`SQLiteDatabase`

The database returned by openDatabase()

SQLiteDatabase Properties

Deprecated Use closeAsync() instead.

`close`

Type: () => Promise<void>

`version`

Type: string

SQLiteDatabase Methods

`closeAsync()`

Close the database.

Returns:

Promise<void>

`closeSync()`

Synchronously closes the database.

Returns:

void

`deleteAsync()`

Delete the database file.

The database has to be closed prior to deletion.

Returns:

Promise<void>

`exec(queries, readOnly, callback)`

Parameter	Type
queries	`Query[]`
readOnly	`boolean`
callback	`SQLiteCallback`

Executes the SQL statement and returns a callback resolving with the result.

Returns:

void

`execAsync(queries, readOnly)`

Parameter	Type
queries	`Query[]`
readOnly	`boolean`

Executes the SQL statement and returns a Promise resolving with the result.

Returns:

Promise<(ResultSetError | ResultSet)[]>

`execRawQuery(queries, readOnly, callback)`

Parameter	Type
queries	`Query[]`
readOnly	`boolean`
callback	`SQLiteCallback`

Due to limitations on Android this function is provided to allow raw SQL queries to be executed on the database. This will be less efficient than using the exec function, please use only when necessary.

Returns:

void

`readTransaction(callback, errorCallback, successCallback)`

Parameter	Type
callback	`SQLTransactionCallback`
errorCallback (optional)	`SQLTransactionErrorCallback`
successCallback (optional)	`() => void`

Returns:

void

`transaction(callback, errorCallback, successCallback)`

Parameter	Type	Description
callback	`SQLTransactionCallback`	A function representing the transaction to perform. Takes a Transaction (see below) as its only parameter, on which it can add SQL statements to execute.
errorCallback (optional)	`SQLTransactionErrorCallback`	Called if an error occurred processing this transaction. Takes a single parameter describing the error.
successCallback (optional)	`() => void`	Called when the transaction has completed executing on the database.

Execute a database transaction.

Returns:

void

`transactionAsync(asyncCallback, readOnly)`

Parameter	Type	Description
asyncCallback	`SQLTransactionAsyncCallback`	A `SQLTransactionAsyncCallback` function that can perform SQL statements in a transaction.
readOnly (optional)	`boolean`	true if all the SQL statements in the callback are read only. Default:`false`

Creates a new transaction with Promise support.

Returns:

Promise<void>

Methods

`SQLite.openDatabase(name, version, description, size, callback)`

Parameter	Type	Description
name	`string`	Name of the database file to open.
version (optional)	`string`	-
description (optional)	`string`	-
size (optional)	`number`	-
callback (optional)	`(db: SQLiteDatabase) => void`	-

Open a database, creating it if it doesn't exist, and return a Database object. On disk, the database will be created under the app's documents directory, i.e. ${FileSystem.documentDirectory}/SQLite/${name}.

The version, description and size arguments are ignored, but are accepted by the function for compatibility with the WebSQL specification.

Returns:

SQLiteDatabase

Interfaces

`Database`

Database objects are returned by calls to SQLite.openDatabase(). Such an object represents a connection to a database on your device.

Database Methods

`readTransaction(callback, errorCallback, successCallback)`

Parameter	Type
callback	`SQLTransactionCallback`
errorCallback (optional)	`SQLTransactionErrorCallback`
successCallback (optional)	`() => void`

Returns:

void

`transaction(callback, errorCallback, successCallback)`

Parameter	Type	Description
callback	`SQLTransactionCallback`	A function representing the transaction to perform. Takes a Transaction (see below) as its only parameter, on which it can add SQL statements to execute.
errorCallback (optional)	`SQLTransactionErrorCallback`	Called if an error occurred processing this transaction. Takes a single parameter describing the error.
successCallback (optional)	`() => void`	Called when the transaction has completed executing on the database.

Execute a database transaction.

Returns:

void

Database Properties

Name	Type	Description
version	`string`	-

`ResultSet`

ResultSet objects are returned through second parameter of the success callback for the tx.executeSql() method on a SQLTransaction (see above).

ResultSet Properties

Name	Type	Description
insertId (optional)	`number`	The row ID of the row that the SQL statement inserted into the database, if a row was inserted.
rows	`{ [column]: any }`	-
rowsAffected	`number`	The number of rows that were changed by the SQL statement.

`ResultSetError`

ResultSetError Properties

Name	Type	Description
error	`Error`	-

`SQLResultSetRowList`

SQLResultSetRowList Methods

`item(index)`

Parameter	Type	Description
index	`number`	Index of row to get.

Returns the row with the given index. If there is no such row, returns null.

Returns:

any

SQLResultSetRowList Properties

Name	Type	Description
_array	`any[]`	The actual array of rows returned by the query. Can be used directly instead of getting rows through rows.item().
length	`number`	The number of rows returned by the query.

`SQLTransaction`

A SQLTransaction object is passed in as a parameter to the callback parameter for the db.transaction() method on a Database (see above). It allows enqueuing SQL statements to perform in a database transaction.

SQLTransaction Methods

`executeSql(sqlStatement, args, callback, errorCallback)`

Parameter	Type	Description
sqlStatement	`string`	A string containing a database query to execute expressed as SQL. The string may contain `?` placeholders, with values to be substituted listed in the `arguments` parameter.
args (optional)	`SQLStatementArg[]`	An array of values (numbers, strings or nulls) to substitute for `?` placeholders in the SQL statement.
callback (optional)	`SQLStatementCallback`	Called when the query is successfully completed during the transaction. Takes two parameters: the transaction itself, and a `ResultSet` object (see below) with the results of the query.
errorCallback (optional)	`SQLStatementErrorCallback`	Called if an error occurred executing this particular query in the transaction. Takes two parameters: the transaction itself, and the error object.

Enqueue a SQL statement to execute in the transaction. Authors are strongly recommended to make use of the ? placeholder feature of the method to avoid against SQL injection attacks, and to never construct SQL statements on the fly.

Returns:

void

`SQLTransactionAsync`

A transaction object to perform SQL statements in async mode.

SQLTransactionAsync Methods

`executeSqlAsync(sqlStatement, args)`

Parameter	Type
sqlStatement	`string`
args (optional)	`SQLStatementArg[]`

Executes a SQL statement in async mode.

Returns:

Promise<ResultSet>

Deprecated Use SQLiteDatabase instead.

`WebSQLDatabase`

Extends: Database

WebSQLDatabase Methods

`closeAsync()`

Close the database.

Returns:

void

`deleteAsync()`

Delete the database file.

The database has to be closed prior to deletion.

Returns:

Promise<void>

`exec(queries, readOnly, callback)`

Parameter	Type
queries	`Query[]`
readOnly	`boolean`
callback	`SQLiteCallback`

Returns:

void

`Window`

Window Properties

Name	Type	Description
openDatabase (optional)	`(name: string, version: string, displayName: string, estimatedSize: number, creationCallback: DatabaseCallback) => Database`	-

Types

`DatabaseCallback()`

Parameter	Type
database	`Database`

Returns:

void

`Query`

Name	Type	Description
args	`unknown[]`	-
sql	`string`	-

`SQLResultSet`

Name	Type	Description
insertId (optional)	`number`	The row ID of the row that the SQL statement inserted into the database, if a row was inserted.
rows	`SQLResultSetRowList`	-
rowsAffected	`number`	The number of rows that were changed by the SQL statement.

`SQLStatementArg`

Literal Type: multiple types

Acceptable values are: string | number | null

`SQLStatementCallback()`

Parameter	Type
transaction	`SQLTransaction`
resultSet	`SQLResultSet`

Returns:

void

`SQLStatementErrorCallback()`

Parameter	Type
transaction	`SQLTransaction`
error	`SQLError`

Returns:

boolean

`SQLTransactionAsyncCallback()`

A transaction callback with given SQLTransactionAsync object to perform SQL statements in async mode.

Parameter	Type
transaction	`SQLTransactionAsync`

Returns:

Promise<void>

`SQLTransactionCallback()`

Parameter	Type
transaction	`SQLTransaction`

Returns:

void

`SQLTransactionErrorCallback()`

Parameter	Type
error	`SQLError`

Returns:

void

`SQLiteCallback()`

Parameter	Type
error (optional)	`Error \| null`
resultSet (optional)	`(ResultSetError \| ResultSet)[]`

Returns:

void