Hello,

I’m having a vexing issue using Ecto.UUIDs as my primary key in a table. When I create a record, I generate the UUID for the id, and pass that along with the other fields to insert. A record is created, and the UUID is shown. When I query the record, I get a different UUID back.

Here’s an example of what I’m seeing. Code for the schema and repo follow the example.

I believe I’m doing something dumb but, at least for me, the dumber it is the harder it is to find.

iex(5)> Repo.insert(%ReplicationType{id: Ecto.UUID.generate(), name: "test3"})
18:32:49.063 [debug] QUERY OK db=0.8ms queue=7.6ms
INSERT INTO `replication_types` (`id`,`name`,`inserted_at`,`updated_at`) VALUES (?,?,?,?) [<<71, 34, 96, 242, 205, 97, 72, 47, 171, 47, 132, 161, 18, 187, 187, 138>>, "test3", ~N[2019-04-19 22:32:49], ~N[2019-04-19 22:32:49]]
{:ok,
 %Pserver.Pserver.ReplicationType{
   __meta__: #Ecto.Schema.Metadata<:loaded, "replication_types">,
   id: "472260f2-cd61-482f-ab2f-84a112bbbb8a",
   inserted_at: ~N[2019-04-19 22:32:49],
   name: "test3",
   replication_tables: #Ecto.Association.NotLoaded<association :replication_tables is not loaded>,
   sites: #Ecto.Association.NotLoaded<association :sites is not loaded>,
   updated_at: ~N[2019-04-19 22:32:49]
 }}
iex(6)> Repo.get_by(ReplicationType, name: "test3")                           
18:33:11.506 [debug] QUERY OK source="replication_types" db=8.9ms
SELECT r0.`id`, r0.`name`, r0.`inserted_at`, r0.`updated_at` FROM `replication_types` AS r0 WHERE (r0.`name` = ?) ["test3"]
%Pserver.Pserver.ReplicationType{
  __meta__: #Ecto.Schema.Metadata<:loaded, "replication_types">,
  id: "4722603f-3f61-482f-3f2f-3f3f123f3f3f",
  inserted_at: ~N[2019-04-19 22:32:49],
  name: "test3",
  replication_tables: #Ecto.Association.NotLoaded<association :replication_tables is not loaded>,
  sites: #Ecto.Association.NotLoaded<association :sites is not loaded>,
  updated_at: ~N[2019-04-19 22:32:49]
}

the code for ReplicationType:

defmodule Pserver.Pserver.ReplicationType do
  use Ecto.Schema
  import Ecto.Changeset
  alias Pserver.Pserver.{ReplicationTable, Site}

  @primary_key {:id, :binary_id, autogenerate: true}
  @foreign_key_type :binary_id
  schema "replication_types" do
    # field :id, :binary_id
    field :name, :string
    
    has_many :sites, Site
    has_many :replication_tables, ReplicationTable
    timestamps()
  end

  @doc false
  def changeset(replication_type, attrs) do
    replication_type
    |> cast(attrs, [:name])
    |> validate_required([:name])
    |> unique_constraint(:name)
  end
end

And the Repo…

defmodule Pserver.Repo do
  use Ecto.Repo,
    otp_app: :pserver,
    adapter: Ecto.Adapters.MySQL
end

Thank you!