models.js

// models/Project.js
module.exports = {
  attributes: {
    title: {
      type: Sequelize.STRING
    }
  },
  associations: function() {
    Project.belongsTo(Customer);
    Project.hasMany(Contributor);
  }
};

// models/Contributor.js
module.exports = {
  attributes: {
    note: {
      type: Sequelize.STRING
    },
  },
  associations: function() {
    Contributor.belongsTo(Project);
    Contributor.belongsTo(User);
  }
};

// models/Customer.js
module.exports = {
  attributes: {
    name: {
      type: Sequelize.STRING
    }
  },
  associations: function() {
    Customer.hasMany(Project);
  }
};

// models/User.js
module.exports = {
  attributes: {
    username: {
      type: Sequelize.STRING
    }
  }
};