"""
    Consultar objetos de la Base de Datos
    con ORM de SQLAlchemy
"""
from sqlalchemy import create_engine
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, Integer, String, Sequence
from sqlalchemy.orm import sessionmaker
from sqlalchemy.orm import aliased


engine = create_engine('sqlite:///:memory:')
Base = declarative_base()

class Author(Base):
    __tablename__ = 'author'

    id = Column(Integer, Sequence('author_id_seq'), primary_key=True)
    firstname = Column(String)
    lastname = Column(String)

    def __repr__(self):
        return "{} {}".format(self.firstname, self.lastname)


Base.metadata.create_all(engine)
author = Author(firstname="Juanita", lastname='Leon')

Session = sessionmaker(bind=engine)
session = Session()
session.add(author)
session.add_all([Author(firstname='Joél Ez', lastname='Silva'),
                 Author(firstname='Jorge', lastname='Olivares')])
session.commit()

"""
    QUERYs

"""
print("Query #1:")
# Devuelve los Autores ordenados por ID.
for instance in session.query(Author).order_by(Author.id):
    print(instance.firstname, instance.lastname)

print("Query #2:")
# Devuelve el Nombre y Apellido de cada Autor
for firstname, lastname in session.query(Author.firstname, Author.lastname):
    print(firstname, lastname)

print("Query #3:")
# Devuelve el Autor, y su primer nombre
for row in session.query(Author, Author.firstname).all():
    print(row.Author, row.firstname)

print("Query #4:")
# Devuelve los Autores, asignando una etiqueta al campo firsname
for row in session.query(Author.firstname.label('firstname_label')).all():
    print(row.firstname_label)

print("Query #5:")
# Devuelve el Autor y su primer nombre, definiendo un alias de la tabla
author_alias = aliased(Author, name='author_alias')
for row in session.query(author_alias, author_alias.firstname).all():
    print(row.author_alias)

print("Query #6:")
# Busqueda de todos los Autores, filtrados por slices, del 2 al 3
for an_author in session.query(Author).order_by(Author.id)[1:3]:
    print(an_author)

print("Query #7:")
# Filtrado por autores con nombre 'Joél Ez'
for name, in session.query(Author.firstname).filter_by(firstname='Joél Ez'):
    print(name)

print("Query #8:")
# Filtrado por apellido del Autor
for name, in session.query(Author.firstname).filter(Author.lastname == 'Silva'):
    print(name)

print("Query #9:")
# Filtrado por nombre de autor y apellido
for an_author in session.query(Author).\
                 filter(Author.firstname == 'Jorge').\
                 filter(Author.lastname == 'Olivares'):
    print(an_author)

print("Query #10")
#  Cantidad de autores con el nombre 'Juanita'
print(session.query(Author).filter(Author.firstname == 'Juanita').count())