NativeScript: How to copy a file from an apps folder to a user accessible folder?

Question

I want to copy storage.db to documents or downloads folder. It's very easy to get the file path:

const filePath = application.android.context.getDatabasePath("storage.db").getAbsolutePath();

But, what isn't that easy is to copy that file to a folder users have access to. I searched this whole forum, and I found nothing useful for my case.

I'm using NativeScript 4.0.1 with vanilla JS.

Answer 1

I finally found the solution. I've seen so many users trying to achieve this, and I hope this will help all of you.

Add this to your AndroidManifest.xml:

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

Install nativescript-permissions:

npm i nativescript-permissions

Asking for permission:

const permissions = require('nativescript-permissions');
permissions.requestPermission(android.Manifest.permission.WRITE_EXTERNAL_STORAGE, "");

Require the necessary modules:

const fileSystemModule = require("tns-core-modules/file-system");
const application = require("application");

Then, create this function where you need to use it:

function copyFile() {
    var myInput = new java.io.FileInputStream(appModule.android.context.getDatabasePath("storage.db").getAbsolutePath());
    
    var myOutput = new java.io.FileOutputStream("/storage/emulated/0/databases/storage.db");

    try {
        var buffer = java.lang.reflect.Array.newInstance(java.lang.Byte.class.getField("TYPE").get(null), 1024);
        var length;
        while ((length = myInput.read(buffer)) > 0) {
            myOutput.write(buffer, 0, length);
        }
    }
    catch (err) {
        console.info("Error", err);
    }


    //Close the streams
    myOutput.flush();
    myOutput.close();
    myInput.close();
}
exports.copyFile = copyFile;

In my case, the file storage.db will be copied to /storage/emulated/0/databases. If you need to create a folder, just do the following:

try {
        var javaFile = new java.io.File("/storage/emulated/0/newfolder");
        if (!javaFile.exists()) {
            javaFile.mkdirs();
            javaFile.setReadable(true);
            javaFile.setWritable(true);
        }
    }
    catch (err) {
        console.info("Error", err);
    }

If the destination folder has a file with the same name as the one you want to copy, you need to remove it first. That's why you should create a specific folder to guarantee it's empty.