Update: I fixed the symptom by changing the column datatypes back to
db.String and casting when a UnicodeDecodError is raised.
db.session.query(cast(Annotations.annotation, sa.Unicode)
However, my feeling is that this is not a great situation as it looks like
I have two different string encodings (?) in the same table-field. This is
because I was running into an issue where long strings passed as query
parameters to _.in() or `==` filters were raising ProgrammingError exceptions
about varchar(max) and text types not being comparable. To work around, I
trapped the exceptions and casted the parameters as db.String in the filter
.filter(cast(AnnotatedData.annotated_string, sa.String) ==
cast(annotation_instance, sa.String)).all()
and inserted the cast'd strings (which shouldn't have been a problem since
the column types were defined as db.String in the first place).
I wonder if this situation is recognizable and if anyone has any advice on
dealing with the situation?
Thanks
On Friday, March 4, 2016 at 2:51:15 PM UTC-5, Tim Pierson wrote:
>
> I've seen a couple of issues regarding mssql and drivers handling of
> strings but I haven't been able to resolve my problem.
>
> I have a flask app with flask-sqlalchemy models defined and a simple query
> is throwing the above complaint about decoding the string.
>
> My connection string:
>
> mssql+pyodbc://[...]/[...]?trusted_connection=yes&charset=utf8&deprecate_large_types=True
> A
>
>
> Which is given to the SQLAlchemy class instance db after the initialization
> of the app with:
>
>
> db.init_app(app)
>
> The offending model:
>
>
> class Annotations(db.Model):
> id = db.Column(db.Integer, primary_key=True)
> creation_date = db.Column(db.DateTime, default=datetime.datetime.now)
> created_by = db.Column(db.String, nullable=False)
> annotation = db.Column(sqlalchemy.Unicode, nullable=False)
> annotation_type_id = db.Column(db.Integer,
> db.ForeignKey('AnnotationTypes.id'))
>
>
>
> The query:
>
>
> db.session.query(Annotations.annotation).all()
>
>
> I've replaced the original column type db.String with sqlalchemy.Unicode on
> the field that throws the error as per an earlier question on this list but
> it hasn't resolved the problem.
>
>
> Could someone offer any pointers?
>
>
> Thanks,
>
>
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