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?

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