On Wed, Aug 29, 2018 at 12:04 AM, yacheng zhu <[email protected]> wrote:
> hi guys, recently I meet a strange error when i use sqlalchemy to insert
> data into a table of mysql.


the error looks like you are passing a string value to a binary
datatype, this needs to be a bytes object, e.g. b'value'.

that's all that really is, there's no evidence of a bug here.  if you
want to illustrate a bug you need to provide a minimal and complete
reproducing test case.

>
> Traceback (most recent call last):
>
>   File "C:\Program
> Files\Python35\lib\site-packages\sqlalchemy\engine\base.py", line 1127, in
> _execute_context
>
>     context = constructor(dialect, self, conn, *args)
>
>   File "C:\Program
> Files\Python35\lib\site-packages\sqlalchemy\engine\default.py", line 694, in
> _init_compiled
>
>     for key in compiled_params
>
>   File "C:\Program
> Files\Python35\lib\site-packages\sqlalchemy\engine\default.py", line 694, in
> <genexpr>
>
>     for key in compiled_params
>
>   File "C:\Program
> Files\Python35\lib\site-packages\sqlalchemy\sql\sqltypes.py", line 877, in
> process
>
>     return DBAPIBinary(value)
>
>   File "C:\Program Files\Python35\lib\site-packages\pymysql\__init__.py",
> line 85, in Binary
>
>     return bytes(x)
>
> TypeError: string argument without an encoding
>
>
>
> It seems that the the value of the variable processors in module
> sqlalchemy\engine\default.py line 690 has some problem
>
>
>                     param = dict(
>
>                         (
>
>                             key,
>
>                             processors[key](compiled_params[key])
>
>                             if key in processors
>
>                             else compiled_params[key]
>
>                         )
>
>                         for key in compiled_params
>
>                     )
>
>
>
> and the variable processsors was assigned at line 652 to equal to
> compiled._bind_processors
>
>
>
>
> when I try to find out the cause of the error, I find an interesting
> appearance that if I watch the variable in debug mode or add the expression
> (in red color)
>
>
>         if statement is not None:
>
>             self.statement = statement
>
>             self.can_execute = statement.supports_execution
>
>             if self.can_execute:
>
>                 self.execution_options = statement._execution_options
>
>             self._bind_processors = self._bind_processors
>
>             self.string = self.process(self.statement, **compile_kwargs)
>
>
> into the module sqlchemy/sql/compiler.py at line 219, the error will not
> occur.
>
>
> In fact, if I add any expression about self._bind_processors, for example
>
>
>         print(self._bind_processors)
>
>
> before calling the self.process method, the error will always disappear.
>
>
> I guess there may be some bug here.
>
>
> --
> SQLAlchemy -
> The Python SQL Toolkit and Object Relational Mapper
>
> http://www.sqlalchemy.org/
>
> To post example code, please provide an MCVE: Minimal, Complete, and
> Verifiable Example. See http://stackoverflow.com/help/mcve for a full
> description.
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-- 
SQLAlchemy - 
The Python SQL Toolkit and Object Relational Mapper

http://www.sqlalchemy.org/

To post example code, please provide an MCVE: Minimal, Complete, and Verifiable 
Example.  See  http://stackoverflow.com/help/mcve for a full description.
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