Unable to Repo.Insert a value into a belongs_to field

Question

I currently have a table that has a field with a belongs_to relationship with another table. When I try and use Repo.insert to add a value to this field I receive an 'is_invalid' error. The error is generated by both seed file and manual command line.

The struct to insert is:

Repo.insert! %Customer_list{
    age: 24,
    first_name: "Tony",
    last_name: "Stark",
    customer_id: "D00001",
    list_date: ~D[2018-09-13],
    consultant_id: 8
  }

The model:

defmodule InformAPI.CTL.Customer_list do
  use Ecto.Schema
  import Ecto.Changeset


  schema "customer_lists" do
    field :age, :integer
    field :first_name, :string
    field :last_name, :string
    field :customer_id, :string
    field :list_date, :date
    belongs_to :consultant_id, InformAPI.CTL.Customer_list_consultants

    timestamps()
  end

  @doc false
  def changeset(customer_list, attrs) do
    Customer_list
    |> cast(attrs, [:customer_id, :first_name, :age, :last_name,  :list_date, :consultant_id])
    |> validate_required([:customer_id, :first_name, :age, :last_name,  :consultant_id, ])
  end
end

All fields except 'consultant_id' can be entered correctly. The 'consultant_id' is a bigint type field in the Postgres DB. The Customer_lists db has the following keys:

customer_lists_consultant_id_fkey
customer_lists_pkey
customer_lists_consultant_id_index

And the customer_lists_consultants table has:

customer_list_consultants_pkey

I'm not sure what is invalid. The consultant_id field won't accept any type of value (String, int etc).

Answer 1

Ecto, by default, assumes that the actual database column of a belongs_to relationship is the name of the declaration plus "_id". In your case, Ecto assumed that the column's name was consultant_id_id and so the value of consultant_id was being ignored by cast.

The fix is to change the name of the relationship to just consultant.

belongs_to :consultant, InformAPI.CTL.Customer_list_consultants