In flutter it's easy to load a .txt asset at runtime by specifying it or its folder in the pubspec.yaml file and then loading it with rootBundle. However, i'm working on a pure dart package, and I'm struggling to work out how to get the package to load a .txt file relative to it's own directory structure.
When I use the package in a separate dart command line application i'm working on, the relative path that I specified in one of the package source code files causes an error to be thrown that the txt file doesn't exist. I understand why this error is being thrown, because the relative path is interpreted as being from the command line application's root directory instead of the package's root directory, but i'm unsure of how to solve this without specifying the absolute path for the .txt file. I'd rather not specify the absolute path as it makes the package less portable.
Is there anything similar to flutter's asset loading for a pure dart package?
I think you need the resolveSymbolicLinks or resolveSymbolicLinksSync methods to decode the relative path and then use the resolved path to read the txt file:
import 'dart:io';
void main() async {
String file = '../lib/main.dart';
var path = Uri.parse('.').resolveUri(Uri.file(file)).toFilePath();
print(path);
if (path == '') path = '.';
var resolved = await File(path).resolveSymbolicLinks();
print(resolved);
File(resolved).readAsString().then((String contents) {
print(contents);
});
}
Related
I want to load the bytes of a file into a variable while testing my flutter application.
I can't use the assets directory as those are bundled with the app and require WidgetsFlutterBinding.ensureInitialized();
I tried searching the file manually with the path package, but this did not seem to work and was rather hacky. That is why i'm searching for a more official approach.
I was thinking way to complicated ...
As Chuck Batson commented, you can just use the path from the projects root for passing it into the (dart:io) File:
File loadResource(String relativePath) {
final filePath = path.join("test", "resources", relativePath);
return File(filePath);
}
(Notice: The above code makes use of the path package for constructing a file path.)
I am writing a Dart package (not Flutter). I have included a few bitmap images as public assets, e.g., lib/assets/empty.png. When this package is running as a command-line app for an end-user, how can I get the file path to these assets on the user's system?
Use-case: My Dart package calls out to FFMPEG, and I need to tell FFMPEG where to find these asset files on the system that's using my package. For example, the call to FFMPEG might look like:
ffmpeg -i "path/to/lib/assets/empty.png" ...
Accessing a Dart package's assets can happen in two modalities:
Running a Dart CLI app with the dart tool and accessing a dependency's assets, or
Running an executable CLI app
The difference between these two situations is that when you're running a CLI app using the dart tool, all of your dependencies are available as structured packages in a local cache on your system. However, when you're running an executable, all relevant code is compiled into a single binary, which means you no longer have access at runtime to your dependencies' packages, you only have access to your dependencies' tree-shaken, compiled code.
Accessing assets when running with dart
The following code will resolve a package asset URI to a file system path.
final packageUri = Uri.parse('package:your_package/your/asset/path/some_file.whatever');
final future = Isolate.resolvePackageUri(packageUri);
// waitFor is strongly discouraged in general, but it is accepted as the
// only reasonable way to load package assets outside of Flutter.
// ignore: deprecated_member_use
final absoluteUri = waitFor(future, timeout: const Duration(seconds: 5));
final file = File.fromUri(absoluteUri);
if (file.existsSync()) {
return file.path;
}
This resolution code was adapted from Tim Sneath's winmd package: https://github.com/timsneath/winmd/blob/main/lib/src/metadatastore.dart#L84-L106
Accessing assets when running an executable
When compiling a client app to an executable, that client app simply cannot access any asset files that were stored with the dependent package. However, there is a work around that may work for some people (it did for me). You can store Base64 encoded versions of your assets in your Dart code, within your package.
First, encode each of your assets into a Base64 string and store those strings somewhere in your Dart code.
const myAsset = "iVBORw0KGgoAAA....kJggg==";
Then, at runtime, decode the string back to bytes, and then write those bytes to a new file on the local file system. Here's the method I used in my case:
/// Writes this asset to a new file on the host's file system.
///
/// The file is written to [destinationDirectory], or the current
/// working directory, if no destination is provided.
String inflateToLocalFile([Directory? destinationDirectory]) {
final directory = destinationDirectory ?? Directory.current;
final file = File(directory.path + Platform.pathSeparator + fileName);
file.createSync(recursive: true);
final decodedBytes = base64Decode(base64encoded);
file.writeAsBytesSync(decodedBytes);
return file.path;
}
This approach was suggested by #passsy
Have a look at the dcli package.
It has a 'pack' command designed to solve exactly this problem.
It encodes assets into dart files that can be unpacked at runtime.
I am using kivy as the GUI and Briefcase as a packaging utility. My .kv file is in the appname/project/src/projectName/resources folder. I also need a .csv file, in the same folder, and want to use pandas with it. I have no problem with importing the packages (I added them to the .toml file). I can't use the full path because when I package the app, the path will be different on each computer. Using relative paths to the app.py file does not work, giving me a file not found error. Is there a way to read a file using a relative path (maybe the source parameter in the .toml file)?
kv = Builder.load_file('resources/builder.kv')
df = pd.read_csv('resources/chemdata.csv')
class ChemApp(App):
def build(self):
self.icon = 'resources/elemental.ico'
return kv
I just encountered and solved a similar problem with Briefcase, even though I was using BeeWare's Toga GUI.
In my case, the main Python file app.py had to access a database file resources/data.csv. In the constructor of the class where I create a main window in app.py, I added the following lines (The import line wasn't there, but included here for clarification):
from pathlib import Path
self.resources_folder = Path(__file__).joinpath("../resources").resolve()
self.db_filepath = self.resources_folder.joinpath("data.csv")
Then I used self.db_filepath to successfully open the CSV file on my phone.
__file__ returns the path to the current file on whatever platform or device.
I'm working on a Lua script which will be hosted by a third party program (some .exe which will call a certain function in my script). In order to implement a functionality I need (make a rest call to a webservice to retrieve certain info) I want to use socket.http.request.
I've first build an example script for the call I wanted to make:
local io = require("io")
local http = require("socket.http")
local ltn12 = require("ltn12")
local data = "some data")
local response = {}
socket.http.request({
method = "POST",
url = "http://localhost:8080/someServce/rest/commands/someCommand",
headers = {
["Content-Type"] = "application/x-www-form-urlencoded",
["Content-Length"] = string.len(data)
},
source = ltn12.source.string(data),
sink = ltn12.sink.table(response)
})
print(table.concat(response))
print("Done")
This works fine. I get the response I expect.
Now when I try to do this from the third party host, I first got an error:
module 'socket.http' not found:
no field package.preload['socket.http']
no file '.\socket\http.lua'
no file 'D:\SomeFolder\lua\socket\http.lua'
no file 'D:\SomeFolder\lua\socket\http\init.lua'
no file 'D:\SomeFolder\socket\http.lua'
no file 'D:\SomeFolder\socket\http\init.lua'
no file 'C:\Program Files (x86)\Lua\5.1\lua\socket\http.luac'
no file '.\socket\http.dll'
no file 'D:\SomeFolder\socket\http.dll'
no file 'D:\SomeFolder\loadall.dll'
no file '.\socket.dll'
no file 'D:\SomeFolder\socket.dll'
no file 'D:\SomeFolder\loadall.dll'
I've tried copying the socket folder from the LUA folder to the folder the host is executing from (D:\SomeFolder). It then finds the module, but fails to load it with another error:
loop or previous error loading module 'socket.http'
I've also tried moving the require statement outside of the function and making it global. This gives me yet another error:
module 'socket.core' not found:
no field package.preload['socket.core']
no file '.\socket\core.lua'
no file 'D:\SomeFolder\lua\socket\core.lua'
no file 'D:\SomeFolder\lua\socket\core\init.lua'
no file 'D:\SomeFolder\socket\core.lua'
no file 'D:\SomeFolder\socket\core\init.lua'
no file 'C:\Program Files (x86)\Lua\5.1\lua\socket\core.luac'
no file 'C:\Program Files (x86)\Lua\5.1\lua\socket\core.lua'
no file '.\socket\core.dll'
no file 'D:\SomeFolder\socket\core.dll'
no file 'D:\SomeFolder\loadall.dll'
no file '.\socket.dll'
no file 'D:\SomeFolder\socket.dll'
no file 'D:\SomeFolder\loadall.dll'
Then I tried copying the core.dll from socket into the D:\SomeFolder folder and it gave me another error:
error loading module 'socket.core' from file '.\socket\core.dll':
%1 is not a valid Win32 application.
Now I'm stuck. I think I must be doing something completely wrong, but I can't find any proper description on how to fix issues like this. Can anyone help me out?
As it turns out, the actual path Lua is going to look for is the problem here. Together with the third party we found that if we put a set of libraries in D:\SomeFolder\ everything now works. So for example there is now a socket.lua in D:\SomeFolder\and there are a socket and a mime forlder there as well.
Rule of thumb appears to be that the location of lua5.1.dll that is bound by the application is leading for the location of any modules you want to load.
You probably need to have the following folder structure (relative to your D:\SomeFolder folder):
socket.lua
socket/core.dll
socket/http.lua
socket/url.lua
socket/<any other file from socket folder required by http.lua>
I just tested this configuration and it works for me.
loop or previous error loading module 'socket.http'
This is usually caused by loading socket.http from socket/http.lua file itself.
I am trying to create HTML files using XSLT, I have used xml file and xsl files to create HTML file. Here some other xsl files which are located in same location are included in xsl file by using <xsl:include href="temp.xsl"/>.
Here Xsl files are located in "D:/XSL_Folder/" path.
I am running Main.java file which is located in D:/Workspace/Webapp_Project/ path.
When i try to create HTML files by using passing "D:/XSL_Folder/root.xsl" and "D:/XML_Folder/data.xml" files to Main.java as arguments, I am getting following error while creating Templates.
Templates lTemplates = TransformerFactory.newInstance().newTemplates(new StreamSource(new FileInputStream(lFileXSL)));
ERROR: 'D:\Workspace\Webapp_Project\temp.xsl (The system cannot find the file specified)'
FATAL ERROR: 'Could not compile stylesheet'
12:20:07 ERROR f.s.t.v.v2.dao.impl.DocUnitDaoImpl - Error while creating a new XslTransformerGetter. The path to the XSL may be wrong.
javax.xml.transform.TransformerConfigurationException: Could not compile stylesheet
at com.sun.org.apache.xalan.internal.xsltc.trax.TransformerFactoryImpl.newTemplates(TransformerFactoryImpl.java:885) ~[na:1.7.0_13]
In error report we can see that parser is checking included xsl file in project path (D:\Workspace\Webapp_Project), not in the path where root.xsl file is located (D:/XSL_Folder/).
Can anyone suggest me why parser searching xsl file in project folder in the path where root.xsl file is located and how to fix this problem?
Code I'm using to create HTML file by using XSL and XML file :
public static void simpleTransform(InputStream lXmlFileStream, File lXSLFile,
StreamResult lHtmlResult, Map<String, String> lArguments) {
TransformerFactory tFactory = TransformerFactory.newInstance();
try {
Transformer transformer =
tFactory.newTransformer(new StreamSource(lXSLFile));
for (Entry<String, String> lEntrie : lArguments.entrySet()) {
transformer.setParameter(lEntrie.getKey(), lEntrie.getValue());
}
transformer.setOutputProperty(OutputKeys.ENCODING, "UTF-8");
transformer.transform(new StreamSource(lXmlFileStream), lHtmlResult);
}
catch (Exception e) {
e.printStackTrace();
}
}
You have tagged the question "saxon", and you have said you are using XSLT 2.0, but the error messages show that you are using Xalan. If you specifically want to use Saxon then the best way is to avoid using the JAXP classpath search and instantiate Saxon directly - in place of TransformerFactory.newInstance(), use new net.sf.saxon.TransformerFactory().
Supplying a File as the argument to StreamSource ought to be OK; but I would like to see how the File lXSLFile object is created. My suspicion would be that you have done something like new File ("root.xsl") and it has been resolved relative to the current directory.
You may try to use <xsl:include href="resolve-uri('temp.xsl')"/> instead of <xsl:include href="temp.xsl"/> to avoid this problem.