[Feature request] override extension file

[jvinai]

I need to enforce a specific extension to the cached file whatever the MIME type of the file is.

It would be nice to have an option for that, for example:

var file = await DefaultCacheManager().getSingleFile(url, {extension: 'my'});

The end result with be a path with file:///somewhere/in/the/phone/myfile.my.

Thank you!

[abdushkur]

I am facing same problem with FireStorage files, download files are stored in cache like this:

these files were mp4, but firebase adds signed key for viewing these files, so when saving these files its extension isn't based on mime type but requested url, if specifying its extension would solve this , then I'd be able load this file to video player.

[Murmurl912]

To fix this, you need to implement a custom HTTP file service that overrides the file extension.
You can copy the HttpFileService class and rewrite the fileExtension part.

You can inspect the HTTP response body and determine the MIME type by analyzing the header information.
But it require more code.

A example would be:

import 'dart:io';

import 'package:clock/clock.dart';
import 'package:flutter_cache_manager/flutter_cache_manager.dart';
import 'package:http/http.dart' as http;
import 'mime_converter.dart'; // fix me, copied it as well
import 'package:path/path.dart' as p;

/// [CustomHttpFileService] is the most common file service and the default for
/// [WebHelper]. One can easily adapt it to use dio or any other http client.
class CustomHttpFileService extends FileService {
  final http.Client _httpClient;

  CustomHttpFileService({http.Client? httpClient}) : _httpClient = httpClient ?? http.Client();

  @override
  Future<FileServiceResponse> get(String url, {Map<String, String>? headers}) async {
    final req = http.Request('GET', Uri.parse(url));
    if (headers != null) {
      req.headers.addAll(headers);
    }
    final httpResponse = await _httpClient.send(req);

    return HttpGetResponse(url, httpResponse);
  }
}

/// Basic implementation of a [FileServiceResponse] for http requests.
class HttpGetResponse implements FileServiceResponse {
  HttpGetResponse(this.url, this._response);

  final String url;

  final DateTime _receivedTime = clock.now();

  final http.StreamedResponse _response;

  @override
  int get statusCode => _response.statusCode;

  String? _header(String name) {
    return _response.headers[name];
  }

  @override
  Stream<List<int>> get content => _response.stream;

  @override
  int? get contentLength => _response.contentLength;

  @override
  DateTime get validTill {
    // Without a cache-control header we keep the file for a week
    var ageDuration = const Duration(days: 7);
    final controlHeader = _header(HttpHeaders.cacheControlHeader);
    if (controlHeader != null) {
      final controlSettings = controlHeader.split(',');
      for (final setting in controlSettings) {
        final sanitizedSetting = setting.trim().toLowerCase();
        if (sanitizedSetting == 'no-cache') {
          ageDuration = Duration.zero;
        }
        if (sanitizedSetting.startsWith('max-age=')) {
          final validSeconds = int.tryParse(sanitizedSetting.split('=')[1]) ?? 0;
          if (validSeconds > 0) {
            ageDuration = Duration(seconds: validSeconds);
          }
        }
      }
    }

    return _receivedTime.add(ageDuration);
  }

  @override
  String? get eTag => _header(HttpHeaders.etagHeader);

  @override
  String get fileExtension {
    var fileExtensionFromUrl = '';
    final urlPath = Uri.tryParse(url)?.path;
    if (urlPath != null) {
      fileExtensionFromUrl = p.extension(urlPath);
    }

    var fileExtension = '';

    final contentTypeHeader = _header(HttpHeaders.contentTypeHeader);
    if (contentTypeHeader != null) {
      final contentType = ContentType.parse(contentTypeHeader);
      fileExtension = contentType.fileExtension;
      if (fileExtensionFromUrl.isNotEmpty && (fileExtension == ".bin" || fileExtension.isEmpty)) {
        fileExtension = fileExtensionFromUrl;
      }
    } else {
      fileExtension = fileExtensionFromUrl;
    }
    return fileExtension;
  }
}

And in mime_converter.dart add your mimeType ext map

// file: mime_converter.dart
import 'dart:io';

///Converts the most common MIME types to the most expected file extension.
extension ContentTypeConverter on ContentType {
  String get fileExtension => mimeTypes[mimeType] ?? ''; // remove the default part
}

/// Source of MIME Types:
/// https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/MIME_types/Common_types
/// Updated on 20th of March in 2020 while being quarantined
const mimeTypes = {
  'application/vnd.android.package-archive': '.apk',
  'application/epub+zip': '.epub',
  'application/gzip': '.gz',
  'application/java-archive': '.jar',
  'application/json': '.json',
  'application/ld+json': '.jsonld',
  'application/msword': '.doc',
  'application/octet-stream': '.bin',
  'application/ogg': '.ogx',
  'application/pdf': '.pdf',
  'application/php': '.php',
  'application/rtf': '.rtf',
  'application/vnd.amazon.ebook': '.azw',
  'application/vnd.apple.installer+xml': '.mpkg',
  'application/vnd.mozilla.xul+xml': '.xul',
  'application/vnd.ms-excel': '.xls',
  'application/vnd.ms-fontobject': '.eot',
  'application/vnd.ms-powerpoint': '.ppt',
  'application/vnd.oasis.opendocument.presentation': '.odp',
  'application/vnd.oasis.opendocument.spreadsheet': '.ods',
  'application/vnd.oasis.opendocument.text': '.odt',
  'application/vnd.openxmlformats-officedocument.presentationml.presentation': '.pptx',
  'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet': '.xlsx',
  'application/vnd.openxmlformats-officedocument.wordprocessingml.document': '.docx',
  'application/vnd.rar': '.rar',
  'application/vnd.visio': '.vsd',
  'application/x-7z-compressed': '.7z',
  'application/x-abiword': '.abw',
  'application/x-bzip': '.bz',
  'application/x-bzip2': '.bz2',
  'application/x-csh': '.csh',
  'application/x-freearc': '.arc',
  'application/x-sh': '.sh',
  'application/x-shockwave-flash': '.swf',
  'application/x-tar': '.tar',
  'application/xhtml+xml': '.xhtml',
  'application/xml': '.xml',
  'application/zip': '.zip',
  'audio/3gpp': '.3gp',
  'audio/3gpp2': '.3g2',
  'audio/aac': '.aac',
  'audio/x-aac': '.aac',
  'audio/midi': '.midi',
  'audio/x-midi': '.midi',
  'audio/x-m4a': '.m4a',
  'audio/m4a': '.m4a',
  'audio/mpeg': '.mp3',
  'audio/ogg': '.oga',
  'audio/opus': '.opus',
  'audio/wav': '.wav',
  'audio/x-wav': '.wav',
  'audio/webm': '.weba',
  'font/otf': '.otf',
  'font/ttf': '.ttf',
  'font/woff': '.woff',
  'font/woff2': '.woff2',
  'image/bmp': '.bmp',
  'image/gif': '.gif',
  'image/jpeg': '.jpg',
  'image/png': '.png',
  'image/svg+xml': '.svg',
  'image/tiff': '.tiff',
  'image/vnd.microsoft.icon': '.ico',
  'image/webp': '.webp',
  'text/calendar': '.ics',
  'text/css': '.css',
  'text/csv': '.csv',
  'text/html': '.html',
  'text/javascript': '.js',
  'text/plain': '.txt',
  'text/xml': '.xml',
  'video/3gpp': '.3gp',
  'video/3gpp2': '.3g2',
  'video/mp2t': '.ts',
  'video/mpeg': '.mpeg',
  'video/ogg': '.ogv',
  'video/webm': '.webm',
  'video/x-msvideo': '.avi',
  'video/quicktime': '.mov',
  'video/mp4': '.mp4',
};