[CB-9810] Mismatch between results of resolveLocalFileSystemURL and FileReader, throws error.

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Invalid
• Affects Version/s: 3.0.0
• Component/s: cordova-plugin-file

Environment

Android SDK 22
Tested on an LG Nexus, Android 5.0.1

• Assignee: Unassigned
• Reporter: Leonel Gayard
• Created: 15/Oct/15 18:16
• Updated: 23/Aug/18 07:10
• Resolved: 29/Oct/15 18:02

Description

The problem

When reading a file with resolveLocalFileSystemURL followed by FileReader.readAsText, the latter fails, with the error message Uncaught TypeError: Failed to execute 'readAsText' on 'FileReader': parameter 1 is not of type 'Blob'.

cordova-plugin-file provides these functions, which match the W3C APIs for File and File System: resolveLocalFileSystemURL and FileReader.

Possible causes ?

It seems the fileEntry object is created inside the Java code, as a JSONObject (method Filesystem#makeEntryForURL; therefore it does not implement the Javascript interfaces File or Blob.

Possible solution ?

Looking at the source of FileReader.js, it seems the FileReader implemented by the plugin delegates to the FileReader of the web view (at least, that's what the name of the variable suggests, `realReader`.

Also, the function in file FileReader.js seems to rely on the attribute localURL of the file object, which is not part of the API.

I made a quick hack on my local installation, to remove the call to the "real" FileReader, and use the one written in Java; this fixed the issue, and makes it possible to use FileReader.

Tested on Android SDK 22, on an LG Nexus, Android 5.0.1.

Example

The repo at https://github.com/leonelag/proto-file-plugin has an example of an application trying to use the plugin to read and write files, and fails on Android.