[CB-13044] Update cordova-plugin-file to latest version of File API

• Type: Task
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Component/s: cordova-plugin-file
• Labels: plugins-next
• Assignee: Unassigned
• Reporter: Filip Maj
• Created: 20/Jul/17 23:08
• Updated: 25/Sep/17 12:21

Description

Part of the roadmap for the core plugins is to update them to make them spec-relevant once more. See CB-12715.
After taking a look at the current version of W3C File API, here is one take on what specific API changes are needed to update the API to the current version:

• remove a bunch of APIs, specifically:
  • everything to do with the old (now discontinued) File System API:
    • window.requestFileSystem method
    • LocalFileSystem object
    • FileSystem object
    • Flags object
    • Metadata object
    • Entry, DirectoryEntry and FileEntry objects
    • DirectoryReader object
  • everything to do with the old, discontinued File Writer API: FileWriter object
  • FileUploadOptions, FileUploadResult objects (wtf are these? I think they are for supporting file transfer? why are they in plugin-file? lol?)
  • the FileError object, as the latest spec says to return DOMException
• update a bunch of APIs, specifically:
  • update FileReader interface's readAs* methods so that they take a Blob object instead of a File object as parameter
  • if the polyfill is still needed, might need to update the File object and remove a bunch of extra native-y cruft like "type" and stuff that was used when leveraging the bridge
  • update any error handling to return DOMException instances instead of the now-removed FileError
• possibly write up a polyfill for Blob ? Looks like it will be needed in Android 4.4 or lower.
• possibly write up a polyfill for FileList (as per spec) - might be needed on iOS 9.3 / Android 4.4. Worth noting that the first descriptive text in the spec mentions this interface being "at risk" as it's basically a glorified array.
• review docs:
  • are referencing local file system paths like <img src="cdvfile://filesystem/path"> still relevant (related to open question #2 below)?
  • review and update https://cordova.apache.org/docs/en/latest/cordova/storage/storage.html#indexeddb - it mentions some things like indexeddb has a 5MB storage, we should probably update it to mention it is supported in ios, and do some quick checking on max storage size.
  • remove https://cordova.apache.org/docs/en/latest/cordova/storage/storage.html#filesystem-api
  • how much of this documentation should reside in the File plugin docs vs. in the general "Storage" cordova docs, or perhaps even the platform docs? over half of the File plugin docs talk about filesystem formats and platform quirks therein.

A few open questions:
1. One thing worth noting is that platform implementations for a lot of the above may not be needed on iOS 10+ and Android 5.0+. Would need to check windows / edge support. If support is splotchy, we need to keep in mind to write the plugin in such a way that we don't clobber over potentially-pre-existing spec-adhering objects of the File API.
2. Worth calling out that the File API defines its own URL scheme to use. Does this then supercede the cordova custom ones like cdvfile:// and other protocols?

Issue Links

• supercedes: CB-12715 File - KEEP

Sub-Tasks

• Update cordova-docs once new File API is ready: Open