you can call "->>" (and any other) operator directly:
Student.data_test.op('->>')('foo') == 'bar'if you want to call cast use this: cast(Student.data_test['foo'], String) == 'bar' "c" (the shortcut for "columns") allows for "Table" instances. If you use declarative style, you can not to use it directly, but if you want: Student.__table__.c.data_test.... Should repeat: there is no need to use __table__ attribute directly with declarative style in most cases. чт, 7 дек. 2017 г., 9:15 <shrey.chau...@invicto.in>: > Hi Mike, > > as you said I tried this: > > *from sqlalchemy.dialects import postgresql * > > > > *class Student(db.Model): # ... > data_test=db.Column(postgresql.JSON) * > > > and I tried querying like this: > > *a = Student.query.filter(Student.data_test["foo"].astext =="bar").first()* > > tried this as well: > *a = > Student.query.filter(Student.data_test["foo"].astext.cast(String)=="bar").first()* > > But still I am getting error: > Traceback (most recent call last): > File "sqlalchemyjson.py", line 46, in <module> > a = Student.query.filter(Student.data_test["foo"].astext > =="bar").first() > File "/usr/lib64/python2.7/site-packages/sqlalchemy/orm/query.py", line > 2690, in first > ret = list(self[0:1]) > File "/usr/lib64/python2.7/site-packages/sqlalchemy/orm/query.py", line > 2482, in __getitem__ > return list(res) > File "/usr/lib64/python2.7/site-packages/sqlalchemy/orm/query.py", line > 2790, in __iter__ > return self._execute_and_instances(context) > File "/usr/lib64/python2.7/site-packages/sqlalchemy/orm/query.py", line > 2813, in _execute_and_instances > result = conn.execute(querycontext.statement, self._params) > File "/usr/lib64/python2.7/site-packages/sqlalchemy/engine/base.py", > line 945, in execute > return meth(self, multiparams, params) > File "/usr/lib64/python2.7/site-packages/sqlalchemy/sql/elements.py", > line 263, in _execute_on_connection > return connection._execute_clauseelement(self, multiparams, params) > File "/usr/lib64/python2.7/site-packages/sqlalchemy/engine/base.py", > line 1053, in _execute_clauseelement > compiled_sql, distilled_params > File "/usr/lib64/python2.7/site-packages/sqlalchemy/engine/base.py", > line 1189, in _execute_context > context) > File "/usr/lib64/python2.7/site-packages/sqlalchemy/engine/base.py", > line 1393, in _handle_dbapi_exception > exc_info > File "/usr/lib64/python2.7/site-packages/sqlalchemy/util/compat.py", > line 203, in raise_from_cause > reraise(type(exception), exception, tb=exc_tb, cause=cause) > File "/usr/lib64/python2.7/site-packages/sqlalchemy/engine/base.py", > line 1182, in _execute_context > context) > File "/usr/lib64/python2.7/site-packages/sqlalchemy/engine/default.py", > line 470, in do_execute > cursor.execute(statement, parameters) > sqlalchemy.exc.ProgrammingError: (psycopg2.ProgrammingError) operator does > not exist: json ->> unknown > LINE 3: WHERE (students.data_test ->> 'foo') = 'bar' > > > > When I use plain json, what should be my query? > > *a = Student.query.filter(cast(**Student**.c.data_test["foo"], String) > =="bar").first()* > > I am getting this: > AttributeError: type object 'Student' has no attribute 'c' > > > > Where am I going wrong? > > -- > 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. > --- > You received this message because you are subscribed to the Google Groups > "sqlalchemy" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to sqlalchemy+unsubscr...@googlegroups.com. > To post to this group, send email to sqlalchemy@googlegroups.com. > Visit this group at https://groups.google.com/group/sqlalchemy. > For more options, visit https://groups.google.com/d/optout. > -- Антон -- 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. --- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com. Visit this group at https://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout.
