Running in a Web Worker

To use the SqlJs driver with sql.js running in a web worker, first update your gradle configuration to generate asynchronous SQLDelight interfaces.

sqldelight {
  databases {
    Database {
      packageName = "com.example"
      generateAsync = true
    }
  }
}

The web worker driver only works with browser targets. In addition to the base webpack configuration needed for the SqlJs driver, the web worker script must also be copied.

// project/webpack.config.d/wasm.js
const CopyWebpackPlugin = require('copy-webpack-plugin');
config.plugins.push(
    new CopyWebpackPlugin({
        patterns: [
            '../../node_modules/sql.js/dist/sql-wasm.wasm',
            '../../node_modules/sql.js/dist/worker.sql-wasm.js'
        ]
    })
);

The function to initialize the driver is a suspend function and must be called within a coroutine. Since this driver is asynchronous, all query functions are also suspend functions.

suspend fun setupDb(): AsyncSqlDriver {
    return initAsyncSqlDriver(schema = Database.Schema)
}

suspend fun getData(database: Database): List<MyData> {
    return database.myDataQueries.getAll().executeAsList()
}

Custom Workers

By default, the js worker driver will load a web worker from /worker.sql-wasm.js (the additional file copied in the webpack config). The driver supports loading custom workers, or workers located at a different path by providing the URL to the initAsyncSqlDriver() function.

initAsyncSqlDriver(workerPath = "/path/to/my/worker.js")

Custom workers must be able to receive and process messages sent by the driver that are defined in the WorkerMessage interface. The driver expects a responding message to be sent that matches the WorkerData interface.

Testing

To run karma tests with the web worker, the karma config must be updated to copy and proxy the worker script file in addition to the WebAssembly file.

// project/karma.config.d/wasm.js
const path = require("path");
const dist = path.resolve("../../node_modules/sql.js/dist/")
const wasm = path.join(dist, "sql-wasm.wasm")
const worker = path.join(dist, "worker.sql-wasm.js")

config.files.push({
    pattern: wasm,
    served: true,
    watched: false,
    included: false,
    nocache: false,
}, {
    pattern: worker,
    served: true,
    watched: false,
    included: false,
    nocache: false,
});

config.proxies["/sql-wasm.wasm"] = `/absolute${wasm}`
config.proxies["/worker.sql-wasm.js"] = `/absolute${worker}`