Organice Android local storage access in android native app

[ieugen]

This issue is to enable organice running as a native Android app to provide access to local files.
IOs should be added later, but is out of scope for this (I don't know IOs).

Workflow should be like this:

• User opens the native file picker dialog to choose a directory where org files live
• (optional) organice will store that location for future use
• organice will read and write org files to that location - the same flow as for web

I believe native android with local storage is achievable.

There is prior work on organice develop branch.
It uses capacitor-js to build a native Android version of organice.
organice runs in a web view and should be able to access native Android (and IOs) filesystem API's via capacitor plugins.

I tried to implement the code with some success using https://github.com/ionic-team/capacitor-plugins/tree/main/filesystem plugin and https://github.com/capawesome-team/capacitor-file-picker .

I managed to create and read files but not control exactly where to put them and also did not manage to use the right native open file dialog (use SD card or other providers) .

I talked with one friend who is familiar with Android dev and also did some checking and I published my findings as comments on

• feat(file-picker): add pickDirectory(...) method capawesome-team/capacitor-plugins#16
• feat: On Android I can't select files on SD card - I see only Photos and Google drive capawesome-team/capacitor-file-picker#60

I think the easiest solution for us long term would be to implement our own capacitor plugin with and API specific to organice.
I believe the Android Java code will be easy to maintain and port to something else then capacitor if there is ever the need.
Also the API surface is small.

The downside of this approach is that the IOs interface should be developed separately (by someone who knows this part)

Related issues:

• Create a plugin: https://capacitorjs.com/docs/plugins/creating-plugins
• Android API's to use https://developer.android.com/guide/topics/providers/document-provider
• Android storage client example code: https://github.com/android/storage-samples/blob/main/StorageClient/Application/src/main/java/com/example/android/storageclient/StorageClientFragment.java
• Provide access to local files - filesystem backend - use web File API #921
• Local File System Adapter #752
• Allow syncing to local filesystem / new sync target #730
• Full offline support #399

[ieugen]

Using Android Storage Access Framework (SAF) we can access any app that implements DocumentProvider.
Thins like Google Drive, NextCloud, DropBox files should be accessible via local filesystem access.

Some of the features offered by the SAF are as follows:
Lets users browse content from all document providers, not just a single app.
Makes it possible for your app to have long term, persistent access to documents owned by a document provider. Through this access users can add, edit, save, and delete files on the provider.
Supports multiple user accounts and transient roots such as USB storage providers, which only appear if the drive is plugged in.

We should use ACTION_OPEN_DOCUMENT_TREE : https://developer.android.com/training/data-storage/shared/documents-files#grant-access-directory

When using ACTION_OPEN_DOCUMENT_TREE, your app gains access only to the files in the directory that the user selects.
Your app can then access any file in the selected directory and any of its sub-directories.

There are some documented restrictions, but I think it does not affect normal user usage:
https://developer.android.com/training/data-storage/shared/documents-files#grant-access-directory

[ieugen]

Capacitor allows us to call an intent with result (e.g. ACTION_OPEN_DOCUMENT_TREE) quite easy:
https://capacitorjs.com/docs/plugins/android#intents-with-results

[ieugen]

I found 2 guides that describe how to use SAF to list and open files.

• https://medium.com/swlh/sample-for-android-storage-access-framework-aka-scoped-storage-for-basic-use-cases-3ee4fee404fc
• https://mateuszteteruk.pl/how-to-use-android-storage-access-framework-with-example

I managed to implement directory picker and directory listing.
See animation bellow:

[danielkrajnik]

Is the native android client still being developed? It would be much easier to use.