Hi there,
I'm learning the active model, and I'm trying to retrieve an association.
My models are:
class Composition < ActiveRecord::Base
has_and_belongs_to_many :materials
belongs_to :product
end
class Material < ActiveRecord::Base
has_and_belongs_to_many :compositions
has_many :products, through: :composition
end
class Product < ActiveRecord::Base
has_many :compositions
has_many :materials, through: :composition
accepts_nested_attributes_for :materials
end
My schema is:
create_table "compositions", force: :cascade do |t|
t.integer "product_id"
t.integer "material_id"
t.integer "material_quantity"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
end
create_table "materials", force: :cascade do |t|
t.string "name"
t.decimal "unit_cost"
t.string "unit_measure"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
end
create_table "products", force: :cascade do |t|
t.string "name"
t.string "description"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
end
On my CompositionsController index method, I would like to retrieve all raw
materials for a product id.
What i have now is:
def index
@product = Product.find(params[:product_id])
@compositions = @product.compositions
end
How do I retrieve materials attributes from @compositions?
When I try to use
@compositions = @product.compositions.includes(:materials)
It gives me the error:
PG::UndefinedTable: ERROR: relation "compositions_materials" does not exist
LINE 5: WHERE a.attrelid = '"compositions_materials"'...
^
: SELECT a.attname, format_type(a.atttypid, a.atttypmod),
pg_get_expr(d.adbin, d.adrelid), a.attnotnull, a.atttypid,
a.atttypmod
FROM pg_attribute a LEFT JOIN pg_attrdef d
ON a.attrelid = d.adrelid AND a.attnum = d.adnum
WHERE a.attrelid = '"compositions_materials"'::regclass
AND a.attnum > 0 AND NOT a.attisdropped
ORDER BY a.attnum
Any hints?
Thanks in advance,
Leandro
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