Cast_assoc invalid

kostonstyle

Hi all
I have following schemas

schema "languages_code" do
   field :code, :string
   field :text, :string

    timestamps
end

and another schema that will be associated with languages_code schema:

schema "countries" do

    belongs_to :code, CountryCode, references: :alpha2
    belongs_to :language, LanguageCode, references: :code
    field :text, :string

    timestamps

  end

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

	  model
	  |> cast(params, [:text])
	  |> cast_assoc(:code)
	  |> cast_assoc(:language)
	  |> validate_required([:code, :language, :text])

  end

Then I test it as follow:

iex(1)> alias Busiket.Country
Busiket.Country
iex(2)> v = %{code: "CH", language: "DE", text: "Schweiz"}
%{code: "CH", language: "DE", text: "Schweiz"}
iex(3)> c = Country.changeset(%Country{}, v)
#Ecto.Changeset<action: nil, changes: %{text: "Schweiz"},
 errors: [language: {"is invalid", [type: :map]},
  code: {"is invalid", [type: :map]}], data: #Busiket.Country<>, valid?: false>
iex(4)>

What is wrong with association?

Update
I tried as follow:

iex(4)> v = %{code: %{code: "CH"}, language: %{alpha2: "DE"}, text: "Schweiz"}
%{code: %{code: "CH"}, language: %{alpha2: "DE"}, text: "Schweiz"}
iex(5)> c = Country.changeset(%Country{}, v)                                  
#Ecto.Changeset<action: nil,
 changes: %{code: #Ecto.Changeset<action: :insert, changes: %{},
    errors: [alpha2: {"can't be blank", []}, alpha3: {"can't be blank", []}],
    data: #Busiket.CountryCode<>, valid?: false>,
   language: #Ecto.Changeset<action: :insert, changes: %{},
    errors: [code: {"can't be blank", []}, text: {"can't be blank", []}],
    data: #Busiket.LanguageCode<>, valid?: false>, text: "Schweiz"}, errors: [],
 data: #Busiket.Country<>, valid?: false>

I’ve forgot to mention, that the data on the language_code table is already available:

I do not have to insert it, only to validate, if the value of the field code of the country is match to the table of language_code.

Thanks

22 comments

#ecto

1 5759 22

2016-11-24 15:25:22 UTC

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josevalim

Creator of Elixir

Constraints are only tested after you do a repository operation, such as Repo.insert, since it is the database reporting what is wrong (rather than we testing it).

Post #11

kostonstyle

So, I have to do Repo.insert to get to know if there is a constraint error or not?

Post #12

josevalim

Creator of Elixir

Yes, that’s by definition how constraints in Ecto work. They rely on the
database as the da abase is the only one who can effectively say if that
relationship exists or not.

Post #13

kostonstyle

My last question(hopefully ), when I tried to insert into db, I’ve got an exception:

iex(5)> e = Repo.insert(c)
[debug] QUERY ERROR db=16.0ms
INSERT INTO "countries" ("iso_country","iso_language","name","inserted_at","updated_at") VALUES ($1,$2,$3,$4,$5) RETURNING "id" ["YY", "DE", "Schweiz", {{2016, 11, 24}, {13, 28, 8, 0}}, {{2016, 11, 24}, {13, 28, 8, 0}}]
** (Ecto.ConstraintError) constraint error when attempting to insert struct:

If you would like to convert this constraint into an error, please
call foreign_key_constraint/3 in your changeset and define the proper
constraint name. The changeset defined the following constraints:

How to get a message instead raised exception?
In doc Ecto.Repo — Ecto v3.14.0 it says, I should get a tuple.

Thanks

Post #14

josevalim

Creator of Elixir

Can you post the full message? The error message is telling exactly what you need to do. You need to pass the :name option to foreign_key_constraint/3 with the foreign key name that is failing.

Post #15

kostonstyle

I’ve found the solution:

  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)
    |> foreign_key_constraint(:iso_language)

  end

It works as expected.
At last, what is the :name options for, that I can pass?

Post #16

kostonstyle

with the name option, I’ve got error as I mentioned above.

Post #17

kostonstyle

So I will post the final code, that works.

  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)
    |> foreign_key_constraint(:iso_language)

  end

Look at the function foreign_key_constraint, I do not pass the name option parameter and it works. Why? What is the use of the name option parameter?

Post #18

josevalim

Creator of Elixir

The name option would be given to the foreign_key_constraint function. If it works without passing the :name option, it means Ecto is guessing the proper name for you.

Post #19

kostonstyle

So, when I what to pass the :name option, how do I have to write?
The migration of countries looks as follow:

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

Thanks

Post #20

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