Rails belongs_to with custom column name
Solution 1:
You must use the name of the association, also need to add the foreign key to the belongs_to
# Returns a FamiliaProducto object
p = Producto.first
p.familia_producto
# Producto model
belongs_to :familia_producto, class_name: 'FamiliaProducto', foreign_key: 'familia'
# FamiliaProducto model
has_many :productos, class_name: 'Producto', foreign_key: 'familia'
# Returns an integer
p = Producto.first
p.familia