wcldyx / cordova-prepopulated-database-demo

Demo of prepopulated databases in Cordova SQLite Plugin 2

Cordova prepopulated database demo

Small app to demonstrate how to use prepopulated databases with Cordova SQLite Plugin 2.

It copies a database file from the read-only www/ directory into the local read-write data directory, then reads from the database to prove that it's working. If the database has already been copied, then it skips that step.

Running this app

Run these commands:

git clone https://github.com/nolanlawson/cordova-prepopulated-database-demo.git
cd cordova-prepopulated-database-demo
cordova plugin add cordova-plugin-file
cordova plugin add cordova-plugin-sqlite-2

Then to run on iOS:

cordova platform add ios
cordova run ios

Or to run on Android:

cordova platform add android
cordova run android

What you'll see:

If you close the app and run it a second time, you'll see it say that there was no need to copy the file.

How it works

Note the mydatabase.db file in www/. This is a simple database, with the following structure:

> .schema
CREATE TABLE mytable (foo text, bar text);
> SELECT * FROM mytable;
hello|world

(You can do sqlite3 www/mydatabase.db on the command line to see this for yourself.)

When the app starts up, it uses the cordova.file API to check if the file has already been copied. If not, it copies it from the read-only application directory (file:///android_asset/ on Android, /var/mobile/Applications/<UUID>/ on iOS) to the data directory (files/ on Android, Library/NoCloud on iOS), where it becomes read-write. For more details, see the Cordova file plugin.

Do it yourself

If you want a simple copy-paste job, you can borrow my own code from this project. Note that you will need a Promise polyfill if you are targeting older versions of Android or iOS:

// copy a database file from www/ in the app directory to the data directory
function copyDatabaseFile(dbName) {
  var sourceFileName = cordova.file.applicationDirectory + 'www/' + dbName;
  var targetDirName = cordova.file.dataDirectory;
  return Promise.all([
    new Promise(function (resolve, reject) {
      resolveLocalFileSystemURL(sourceFileName, resolve, reject);
    }),
    new Promise(function (resolve, reject) {
      resolveLocalFileSystemURL(targetDirName, resolve, reject);
    })
  ]).then(function (files) {
    var sourceFile = files[0];
    var targetDir = files[1];
    return new Promise(function (resolve, reject) {
      targetDir.getFile(dbName, {}, resolve, reject);
    }).then(function () {
      console.log("file already copied");
    }).catch(function () {
      console.log("file doesn't exist, copying it");
      return new Promise(function (resolve, reject) {
        sourceFile.copyTo(targetDir, dbName, resolve, reject);
      }).then(function () {
        console.log("database file copied");
      });
    });
  });
}

Then:

copyDatabaseFile('mydatabase.db').then(function () {
  // success! :)
}).catch(function (err) {
  // error! :(
  console.log(err);
});

Within the "success" handler, just call sqlitePlugin.openDatabase() like you normally would, and the database will be ready.