old_contents: from . import db
  
  class Item(db.Model):
      
      id = db.Column(db.Integer, primary_key=True, autoincrement=False)
      name = db.Column(db.String(100), nullable=True)
      max_production_limit = db.Column(db.Integer, nullable=True)
      
      # foreign keys
      activities = db.relationship('Activity', backref='blueprint', lazy='dynamic')
      activity_products = db.relationship('ActivityProduct', backref='blueprint', lazy='dynamic', foreign_keys='ActivityProduct.item_id')
      activity_skills = db.relationship('ActivitySkill', backref='blueprint', lazy='dynamic', foreign_keys='ActivitySkill.item_id')
      activity_materials = db.relationship('ActivityMaterial', backref='blueprint', lazy='dynamic', foreign_keys='ActivityMaterial.item_id')
      
      product_for_activities = db.relationship('ActivityProduct', backref='product', lazy='dynamic', foreign_keys='ActivityProduct.product_id')
      skill_for_activities = db.relationship('ActivitySkill', backref='skill', lazy='dynamic', foreign_keys='ActivitySkill.skill_id')
      material_for_activities = db.relationship('ActivityMaterial', backref='material', lazy='dynamic', foreign_keys='ActivityMaterial.material_id')
      
  
new_contents: from . import db
  from .activity import Activity
  from flask import url_for
  
  
  class Item(db.Model):
      
      id = db.Column(db.Integer, primary_key=True, autoincrement=False)
      name = db.Column(db.String(100), nullable=True)
      max_production_limit = db.Column(db.Integer, nullable=True)
  
      # foreign keys
      activities = db.relationship('Activity', backref='blueprint', lazy='dynamic')
      activity_products = db.relationship('ActivityProduct', backref='blueprint', lazy='dynamic', foreign_keys='ActivityProduct.item_id')
      activity_skills = db.relationship('ActivitySkill', backref='blueprint', lazy='dynamic', foreign_keys='ActivitySkill.item_id')
      activity_materials = db.relationship('ActivityMaterial', backref='blueprint', lazy='dynamic', foreign_keys='ActivityMaterial.item_id')
      
      product_for_activities = db.relationship('ActivityProduct', backref='product', lazy='dynamic', foreign_keys='ActivityProduct.product_id')
      skill_for_activities = db.relationship('ActivitySkill', backref='skill', lazy='dynamic', foreign_keys='ActivitySkill.skill_id')
      material_for_activities = db.relationship('ActivityMaterial', backref='material', lazy='dynamic', foreign_keys='ActivityMaterial.material_id')
      
      def icon_32(self):
          static_url = "ccp/Types/%d_32.png" % self.id
          return url_for('static', filename=static_url)
  
      def icon_64(self):
          static_url = "ccp/Types/%d_64.png" % self.id
          return url_for('static', filename=static_url)
  
      def is_manufactured(self):
          if self.product_for_activities.filter_by(activity=Activity.ACTIVITY_MANUFACTURING).count() > 0:
              return True
          return False
subject: Add methods