from flask.ext.sqlalchemy import SQLAlchemy
from sqlalchemy.exc import SQLAlchemyError

db = SQLAlchemy()


class CRUD():

    def session_commit(self):
        try:
           db.session.commit() 
        except SQLAlchemyError as e:
            db.session.rollback()
            reason = str(e)
            return reason

    def add(self, resource):
        db.session.add(resource)
        #return self.session_commit()
        db.session.commit()

    def read(self):
        return self.query.all()

    def update(self):
        return self.session_commit()

    def delete(self, resource):
        db.session.delete(resource)
        return self.session_commit()