# Import/Export

Nitrite provides import/export functionality via nitrite-support library. You can import/export your database to/from a file in JSON format. You can choose to import/export the entire database or a specific collection.

To export the entire database in JSON format, you can use the Exporter class of nitrite-support library. You can use the Exporter.withOptions() method to construct an instance of Exporter.

// create an exporter with export options
var exporter = Exporter.withOptions(
    dbFactory: () async => createDb('nitrite_source.db'),
    collections: ['first'],
    repositories: ['Employee'],
    keyedRepositories: {
        'key': {'Employee'},
    },
);

// export the database to a file
await exporter.exportTo(dataFile);

The Exporter.withOptions() method provides various options to configure the export process. You can set the following options:

• dbFactory - the NitriteFactory function to use for export. It is used to create the Nitrite instance for export. It's a mandatory field.
• exportIndices - whether to export indices or not. It's an optional field, if not provided, it will be set to true.
• exportData - whether to export data or not. It's an optional field, if not provided, it will be set to true.
• collections - the list of collections to export. The rules for specifying the collection names are as follows:
  • If null is specified, all collections will be exported.
  • If an empty list is specified, no collection will be exported.
  • If a non-empty list is specified, only the collections in the list will be exported.
• repositories - the list of repositories to export. The rules for specifying the repository names are as follows:
  • If null is specified, all repositories will be exported.
  • If an empty list is specified, no repository will be exported.
  • If a non-empty list is specified, only the repositories in the list will be exported.
• keyedRepositories - the map of keyed repositories to export. The rules for specifying the keyed repository names are as follows:
  • If null is specified, all keyed repositories will be exported.
  • If an empty map is specified, no keyed repository will be exported.
  • If a non-empty map is specified, only the keyed repositories in the map will be exported.

First create a method to create a Nitrite instance, which will be used as the nitriteFactory.

Future<Nitrite> createDb(String filePath) async {
    // create a Hive based file store
    var storeModule = Hive.withConfig()
        .path(filePath)
        .build();

    // open the database
    return Nitrite.builder()
        .loadModule(storeModule)
        .build();
}

Then create the Exporter instance and export the database.

// create an exporter with export options
var exporter = Exporter.withOptions(
    dbFactory: () async => createDb('nitrite_source.db'),
    collections: ['first'],
    repositories: ['Employee'],
    keyedRepositories: {
        'key': {'Employee'},
    },
);

// export the database to a file
await exporter.exportTo('source.json');

The source.json file will contain the exported data in JSON format.

To import the entire database from an exported JSON data, you can use the Importer class of nitrite-support library. You can use the Importer.withOptions() method to construct an instance of Importer.

// create an importer with import options
var importer = Importer.withOptions(
    dbFactory: () async => createDb(getTempPath('nitrite_dest.db')),
);

// import the database from a file
await importer.importFrom('source.json');

The Importer.withOptions() method provides various options to configure the import process. You can set the following options:

• dbFactory - the NitriteFactory function to use for import. It is used to create the Nitrite instance for import. It's a mandatory field.

First create the Importer instance and configure it.

// create an importer with import options
var importer = Importer.withOptions(
    dbFactory: () async => createDb('nitrite_dest.db'),
);

// import the database from a file
await importer.importFrom('source.json');

The nitrite_dest.db file will contain the imported data. You can open the database and use it.