old_contents: # -*- coding: utf-8 -*-
  
  """
  Work in progress:
  - add missing tables
  - add foreign keys and back population between tables
  """
  
  from sqlalchemy import Column, ForeignKey, Integer, String
  from sqlalchemy.ext.declarative import declarative_base
  from sqlalchemy.orm import relationship
  
  Base = declarative_base()
  
  class Metabolite(Base):
      """Table which stores the metabolite and its descriptive information."""
      __tablename__ = "metabolite"
  
      id = Column(Integer, primary_key=True)
      accession = Column(String, nullable=False)
      formula = Column(String, nullable=False)
      mol_weight = Column(float, nullable=True)
      iupac = Column(String, nullable = False)
      trivial = Column(String, nullable=True)
      cas_id = Column(String, nullable=True)
      smiles = Column(String, nullable=True)
      inchi = Column(String, nullable=True)
      inchi_key = Column(String, nullable=True)
  
      biofluids = relationship('')
  
  class Biofluid_loc(Base):
      """possible biofluids"""
      __tablename__ = "biofluid location"
  
      id = Column(Integer, primary_key=True)
      biofluid = Column(String, nullable=False)
  
  class Substituents(Base):
      """Stores the different substituents"""
      __tablename__ = "substituents"
  
      id = Column(Integer, primary_key=True)
      substituent = Column(String, nullable=False)
  
  class Cellular_loc(Base):
      """Stores the possible cellular locations"""
      __tablename__ = "cellular location"
  
      id = Column(Integer, primary_key=True)
      cellular_loc = Column(String, nullable=False)
  
  class Tissues(Base):
      """Stores the possible tissues"""
      __tablename__ = "tissues"
  
      id = Column(Integer, primary_key=True)
      tissue = Column(String, nullable=False)
  
  
new_contents: # -*- coding: utf-8 -*-
  
  """
  Work in progress:
  - add missing tables
  - add foreign keys and back population between tables
  """
  
  from sqlalchemy import Column, ForeignKey, Integer, String, Float
  from sqlalchemy.ext.declarative import declarative_base
  from sqlalchemy.orm import relationship
  
  Base = declarative_base()
  
  class Metabolite(Base):
      """Table which stores the metabolite and its descriptive information."""
      __tablename__ = "metabolite"
  
      id = Column(Integer, primary_key=True)
      accession = Column(String, nullable=False)
      formula = Column(String, nullable=False)
      mol_weight = Column(Float, nullable=True)
      iupac = Column(String, nullable = False)
      trivial = Column(String, nullable=True)
      cas_id = Column(String, nullable=True)
      smiles = Column(String, nullable=True)
      inchi = Column(String, nullable=True)
      inchi_key = Column(String, nullable=True)
  
      biofluids = relationship('')
  
  class Biofluid_loc(Base):
      """possible biofluids"""
      __tablename__ = "biofluid location"
  
      id = Column(Integer, primary_key=True)
      biofluid = Column(String, nullable=False)
  
  class Substituents(Base):
      """Stores the different substituents"""
      __tablename__ = "substituents"
  
      id = Column(Integer, primary_key=True)
      substituent = Column(String, nullable=False)
  
  class Cellular_loc(Base):
      """Stores the possible cellular locations"""
      __tablename__ = "cellular location"
  
      id = Column(Integer, primary_key=True)
      cellular_loc = Column(String, nullable=False)
  
  class Tissues(Base):
      """Stores the possible tissues"""
      __tablename__ = "tissues"
  
      id = Column(Integer, primary_key=True)
      tissue = Column(String, nullable=False)
  
  
subject: Use SQLAlchemy Float instead of Python float