Flask: Cannot convert bytes object to java.lang.String

[matsbohlinsson]

Im trying to run flask. During startup if flask, I get the following runtime error:
TypeError: Cannot convert bytes object to java.lang.String

Seems related to call:click.echo()

 main()
  File "/data/user/0/com.plainembedded.mavicmax/files/chaquopy/AssetFinder/requirements/flaskcode/cli.py", line 59, in main
  File "/data/user/0/com.plainembedded.mavicmax/files/chaquopy/AssetFinder/requirements/click/core.py", line 829, in __call__
  File "/data/user/0/com.plainembedded.mavicmax/files/chaquopy/AssetFinder/requirements/click/core.py", line 782, in main
  File "/data/user/0/com.plainembedded.mavicmax/files/chaquopy/AssetFinder/requirements/click/core.py", line 1066, in invoke
  File "/data/user/0/com.plainembedded.mavicmax/files/chaquopy/AssetFinder/requirements/click/core.py", line 610, in invoke
  File "/data/user/0/com.plainembedded.mavicmax/files/chaquopy/AssetFinder/requirements/flaskcode/cli.py", line 50, in run
  File "/data/user/0/com.plainembedded.mavicmax/files/chaquopy/AssetFinder/requirements/click/utils.py", line 272, in echo
  **File "bootstrap/java/android/stream.py", line 59, in write
  File "class.pxi", line 781, in java.chaquopy.JavaMethod.__call__
  File "conversion.pxi", line 256, in java.chaquopy.p2j**
TypeError: Cannot convert bytes object to java.lang.String

My code:

from flask import Flask
import flaskcode

app = Flask(__name__)
app.config.from_object(flaskcode.default_config)
app.config['FLASKCODE_RESOURCE_BASEPATH'] = '/sdcard/mavicmax/'
app.register_blueprint(flaskcode.blueprint, url_prefix='/flaskcode')

@app.route('/')
def hello():
    return "Hello World!"

if __name__ == '__main__':
    app.run()

[mhsmith]

I've run your code and it doesn't reproduce the issue. In fact, it doesn't look like your code even uses flaskcode.cli, so please explain how flaskcode.cli.main is being called.

Also, what version of Chaquopy are you using?

[matsbohlinsson]

Version: classpath 'com.chaquo.python:gradle:9.1.0'

I uploaded the code to cloned version of your examples repo:
https://github.com/matsbohlinsson/chaquopy-hello-test/commits/master

The latest commit in the repo is exactly what I'm running. You should be able to reproduce it, I hope :-)

The last commit causes the stacktrace below:

D/AndroidRuntime: Shutting down VM
E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.chaquo.python.hello, PID: 28891
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.chaquo.python.hello/hello.MainActivity}: com.chaquo.python.PyException: TypeError: Cannot convert bytes object to java.lang.String
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3308)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3457)
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83)
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2044)
        at android.os.Handler.dispatchMessage(Handler.java:107)
        at android.os.Looper.loop(Looper.java:224)
        at android.app.ActivityThread.main(ActivityThread.java:7560)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:539)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:950)
     Caused by: com.chaquo.python.PyException: TypeError: Cannot convert bytes object to java.lang.String
        at <python>.java.chaquopy.p2j(conversion.pxi:256)
        at <python>.java.chaquopy.JavaMethod.__call__(class.pxi:781)
        at <python>.java.android.stream.write(stream.py:59)
        at <python>.click.utils.echo(utils.py:272)
        at <python>.flask.cli.show_server_banner(cli.py:670)
        at <python>.flask.app.run(app.py:985)
        at <python>.hello.onCreate(hello.py:19)
        at <python>.chaquopy_java.call(chaquopy_java.pyx:380)
        at <python>.chaquopy_java.Java_com_chaquo_python_PyObject_callAttrThrowsNative(chaquopy_java.pyx:352)
        at com.chaquo.python.PyObject.callAttrThrowsNative(Native Method)
        at com.chaquo.python.PyObject.callAttrThrows(PyObject.java:232)
        at com.chaquo.python.PyObject._chaquopyCall(PyObject.java:239)
        at hello.MainActivity.onCreate(MainActivity.java:24)
        at android.app.Activity.performCreate(Activity.java:7894)
        at android.app.Activity.performCreate(Activity.java:7881)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1307)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3283)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3457) 
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83) 
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135) 
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2044) 
        at android.os.Handler.dispatchMessage(Handler.java:107) 
        at android.os.Looper.loop(Looper.java:224) 
        at android.app.ActivityThread.main(ActivityThread.java:7560) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:539) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:950) 
I/Process: Sending signal. PID: 28891 SIG: 9

[mhsmith]

OK, it looks like there's an incompatibility between the way click accesses stdout and the way Chaquopy redirects it to Logcat. We'll fix this in the next version of Chaquopy. Meanwhile, you can work around the problem by adding the following code to the start of your Python file:

import sys
for stream in [sys.stdout, sys.stderr]:
    def write_override(s, write_original=stream.write):
        if not isinstance(s, str):
            raise TypeError()
        return write_original(s)
    stream.write = write_override

[matsbohlinsson]

Wow it works!!

Thank you, this was a major thing for me!

[mhsmith]

This issue is fixed in Chaquopy 10.0.1. To upgrade, edit your app's top-level build.gradle file and change the version number of com.chaquo.python:gradle.