How to load resource files or package: URI in Dart?

Question

There is a way to get the path to the currently executing script, and then find the resource files relative to this location, but there is no guarantee that the directory structure is the same when publishing the application.

Does Dart provide a general way to load resources (files, data, ...) in a way that also works with pub run or pub global run ?

Given a different way, how do I dynamically load the contents of a package: URI in a Dart application at runtime?

Answer 1

An update to the resource package has been published.

Update This is being recycled. The Resource class will be moved to the package.

Original

Dart has a new Resource class (tested with Dart VM version: 1.12.0-edge.d4d89d6f12b44514336f1af748e466607bcd1453 (Fri Aug 7 19:38:14 2015) )

resource_example / Library / resources / sample.txt

 Sample text file. 

resource_example / bin / main.dart

 main() async { var resource = const Resource('package:resource_example/resource/sample.txt'); print(await resource.readAsString()); // or for binary resources // print(await resource.readAsBytes()); } 

Performance

 dart bin/main.dart 

prints

 Sample text file. 

Performance

 pub global activate -spath . pub global run resource_example:main 

also prints

 Sample text file. 

It is also possible to pass the contents of a variable as a resource. This may, for example, be convenient in unit tests for transferring mock resources.

 const sampleText = "Sample const text"; main() async { var uriEncoded = sampleText.replaceAll(' ', '%20'); var resource = new Resource('data:application/dart;charset=utf-8,$uriEncoded'); print(await resource.readAsString()); } 

Arbitrary files or http uris are also supported, but this may not work when using pub run or pub global run when using relative paths.

 main() async { var uri = new Uri.file('lib/resource/sample.txt'); var resource = new Resource(uri.toString()); print(await resource.readAsString()); } 

See details
- http://blog.sethladd.com/2015/08/dynamically-load-package-contents-with.html
- https://codereview.chromium.org/1276263002/