从批处理脚本中调用Powershell命令时，双引号是否不能从字符串转义？

Question

Double quotes structure is not retained in my test message when passed through a powershell instance called through a batch script, as detailed below:

set test={"this":"is","a":"test"}
FOR /F "delims=" %%i in (' powershell -Command "& {$message = '%test%'; echo $message}" ') DO SET message=%%i
echo %test%
echo %message%

the output is as follows:

{"this":"is","a":"test"}
{this:is,a:test}

I would like to retain the quotes to further process the string in powershell, but as you can see, they are stripped when introduced into the $message variable.

Any insight as to how I might fix this?

Answer 1

Echoing %test% containing double quotes inside the d-quoted powershell command will break the enclosing d-quotes.

One way to overcome this, is using batch string substitution to escape the inner d-quotes with a backslash on the fly

:: Q:\Test\2019\04\25\SO_55855412.cmd
@Echo off
set "test={"this":"is","a":"test"}"
FOR /F "delims=" %%i in ('
     powershell -Command "& {$message = '%test:"=\"%'; echo $message}" 
') DO SET "message=%%i"
echo %test%
echo %message%

returns here:

> SO_55855412.cmd
{"this":"is","a":"test"}
{"this":"is","a":"test"}

Another solution is to NOT pass %test% as an argument, but to get the variable from the inherited environment

    powershell -Command "& {$message = $env:test; echo $message}"

Sadly this doesn't work to pass a variable back, as on terminating the spawned app the inherited environment is discarded.