Cast_assoc invalid

If you don’t need to insert it, just validate it exists, you can let the database take care of it for you:

schema "countries" do
   field :code
   field :language
   field :text
   timestamps
end

def changeset(struct, params \\ %{}) do
  struct
  |> cast(params, [:text, :code, :language])
  |> validate_required([:code, :language, :text])
  |> foreign_key_constraint(:code, name: :name_of_the_code_foreign_key)
  |> foreign_key_constraint(:language, name: :name_of_the_language_foreign_key)
end

Then you can query your database to find the name of the foreign keys. If you are not sure the foreign key exists, then you can try to insert a country with a code that certainly does not exist and Ecto will error, telling you which foreign key name that failed, or succeed, which means you have no primary keys and therefore you should add one.

First of all, thanks for your answer.

Do I need anymore?

|> cast_assoc(:code)
|> cast_assoc(:language)

or just:

def changeset(struct, params \\ %{}) do
  struct
  |> cast(params, [:text])
  |> validate_required([:code, :language, :text])
  |> foreign_key_constraint(:code, name: :name_of_the_code_foreign_key)
  |> foreign_key_constraint(:language, name: :name_of_the_language_foreign_key)
end

Thanks

Sorry, you are right. You don’t need cast_assoc but make sure you pass both :code and :language to cast. I will edit my previous answer for clarify.

Thanks jose.

Did it work?

Sorry.
I changed my schema to:

schema "countries" do

    field :code, :string
    field :language, :string
    field :text, :string

    timestamps

  end

  def changeset(model, params \\ %{}) do

	  model
	  |> cast(params, [:code, :language, :text])
	  |> validate_required([:code, :language, :text])
	  |> foreign_key_constraint(:code, name: :alpha2)
      |> foreign_key_constraint(:language, name: :code)

  end

as output

iex(11)> v = %{code: "LK", language: "ZZ", text: "Schweiz"}
%{code: "LK", language: "ZZ", text: "Schweiz"}
iex(12)> c = Country.changeset(%Country{}, v)              
#Ecto.Changeset<action: nil,
 changes: %{code: "LK", language: "ZZ", text: "Schweiz"}, errors: [],
 data: #Busiket.Country<>, valid?: true>

It should complain, a country with code LK does not exists!

Thanks

@josevalim I found the error, it is on migration file, since I rename the column:

create table(:countries) do
  add :coun, references(:countries_code, column: :alpha2, type: :string)
  add :lang, references(:languages_code, column: :code, type: :string)
  add :text, :string

  timestamps
		end

create unique_index(:countries, [:coun, :lang])

I rename the column from coun to code and from lang to language.
Now how to add references to the new name of columns?

Delete and create the countries database with:

  def change do

    drop table(:countries)

    create table(:countries) do
      add :code, references(:countries_code, column: :alpha2, type: :string)
      add :language, references(:languages_code, column: :code, type: :string)
      add :text, :string

      timestamps
    end

    create unique_index(:countries, [:code, :language])

  end

and tried with:

iex(2)> v = %{code: "LK", language: "ZZ", text: "Schweiz"}
%{code: "LK", language: "ZZ", text: "Schweiz"}
iex(3)> c = Country.changeset(%Country{}, v)  
#Ecto.Changeset<action: nil,
 changes: %{code: "LK", language: "ZZ", text: "Schweiz"}, errors: [],
 data: #Busiket.Country<>, valid?: true>

The compiler should complain.

If you are using “references”, one is automatically added for you. Please
check the answer in my first post, I think you did not add the new fields
to the “cast” call in your changeset function (because I forgot to do so as
well in my original reply).

Hi jose
I tried again as you metioned and it does not work.

The schema and changeset function:

  schema "countries" do

    field :iso_country, :string
    field :iso_language, :string
    field :name, :string

    timestamps

  end

  def changeset(struct, params \\ %{}) do

    struct
    |> cast(params, [:iso_country, :iso_language, :name])
    |> validate_required([:iso_country, :iso_language, :name])
    |> foreign_key_constraint(:iso_country, name: :iso)
    |> foreign_key_constraint(:iso_language, name: :iso)

  end

and migration:

def change do

create table(:countries) do

  add :iso_country, references(:countries_code, column: :iso, type: :string)
  add :iso_language, references(:languages_code, column: :iso, type: :string)
  add :name, :string

  timestamps
end

create unique_index(:countries, [:iso_country, :iso_language])

When I look at the pgAdmin console, the migration did the right job:

23-11-_2016_16-42-15.png328×266 6.96 KB

as you can see on the picture, the constraints on countries table is available.

I test as follow:

iex(4)> a = %{iso_country: "YY", iso_language: "DE", name: "Schweiz"}
%{iso_country: "YY", iso_language: "DE", name: "Schweiz"}
iex(5)> Country.changeset(%Country{}, a)
#Ecto.Changeset<action: nil,
 changes: %{iso_country: "YY", iso_language: "DE", name: "Schweiz"}, errors: [],
 data: #Busiket.Country<>, valid?: true>

The country with iso YY does not exists on countries_code db:

23-11-_2016_16-45-20.png447×104 3.08 KB

What am I doing wrong?

Thanks.