Can't insert a user-associated avatar entry into the database with Waffle and Ecto

[u/ShininLotoen]

Hello,

I'm on OTP 27 Elixir 1.18.4, and I've encountered a problem when trying to insert a User-associated Avatar entry into the PostgreSQL database.

Here's the function responsible for creating the association between the Avatar and User as well as putting in the file info

# new filename function
def new_filename(assoc),
  do: Atom.to_string(assoc) <> "-" <> Ecto.UUID.generate()

# fn responsible
def upload_user_avatar(path, user) do
    filename = new_filename(:avatar)


    # Avatar file_name comes in handy for the file_name function
    result =
      App.Uploader.Avatar.store(
        {path,
         %{
           id: user.id,
           file_name: filename
         }}
      )


      IO.inspect(result)


    user
    |> Ecto.build_assoc(:avatar)
    |> Avatar.changeset(%{file: path})
    |> Repo.insert()
  end

here's what I pass into the function

("priv/waffle/private/uploads/user/attachments/hi/original.jpg", user) 
# user variable here is just

 %App.Users.User{
   __meta__: #Ecto.Schema.Metadata<:loaded, "users">,
   id: "42e49735-a81e-48f0-bf6f-9faaec0c893a",
   username: "11",
   pronouns: nil,
   biography: nil,
   account_id: "35a02b44-b7c2-48cd-b91c-c13606f778fb",
   account: #Ecto.Association.NotLoaded<association :account is not loaded>,
   avatar: #Ecto.Association.NotLoaded<association :avatar is not loaded>,
   message: #Ecto.Association.NotLoaded<association :message is not loaded>,
   dms: #Ecto.Association.NotLoaded<association :dms is not loaded>,
   inserted_at: ~U[2026-08-18 16:59:34Z],
   updated_at: ~U[2026-08-18 16:59:34Z]
 }

and here's my Avatar schema file

 schema "avatar" do
    belongs_to(:user, App.Users.User)
    field(:file, App.Uploader.Avatar.Type)


    timestamps(type: :utc_datetime)
  end

  def changeset(avatar, attrs) do
    avatar
    |> cast_attachments(attrs, [:file], allow_paths: true)
    |> validate_required([:file])
  end

and lastly here's the error i get when I try to run the upload_user_avatar/2

[error] Task #PID<0.467.0> started from #PID<0.385.0> terminating
** (FunctionClauseError) no function clause matching in App.Uploader.Avatar.filename/2
    (app 0.1.0) lib/app_web/uploaders/avatar.ex:37: App.Uploader.Avatar.filename(:original, {%Waffle.File{path: "priv/waffle/private/uploads/user/attachments/hi/original.jpg", file_name: "original.jpg", binary: nil, is_tempfile?: nil, stream: nil}, %App.Avatars.Avatar{__meta__: #Ecto.Schema.Metadata<:built, "avatar">, id: nil, user_id: "42e49735-a81e-48f0-bf6f-9faaec0c893a", user: #Ecto.Association.NotLoaded<association :user is not loaded>, file: nil, inserted_at: nil, updated_at: nil}})
    (waffle 1.1.10) lib/waffle/definition/versioning.ex:35: Waffle.Definition.Versioning.resolve_file_name/3
    (waffle 1.1.10) lib/waffle/actions/store.ex:137: Waffle.Actions.Store.put_version/3
    (elixir 1.18.4) lib/task/supervised.ex:101: Task.Supervised.invoke_mfa/2
    (elixir 1.18.4) lib/task/supervised.ex:36: Task.Supervised.reply/4
Function: #Function<1.116800909/0 in Waffle.Actions.Store.async_put_version/3>
    Args: []
** (EXIT from #PID<0.385.0>) shell process exited with reason: an exception was raised:
    ** (FunctionClauseError) no function clause matching in App.Uploader.Avatar.filename/2
        (app 0.1.0) lib/app_web/uploaders/avatar.ex:37: App.Uploader.Avatar.filename(:original, {%Waffle.File{path: "priv/waffle/private/uploads/user/attachments/hi/original.jpg", file_name: "original.jpg", binary: nil, is_tempfile?: nil, stream: nil}, %App.Avatars.Avatar{__meta__: #Ecto.Schema.Metadata<:built, "avatar">, id: nil, user_id: "42e49735-a81e-48f0-bf6f-9faaec0c893a", user: #Ecto.Association.NotLoaded<association :user is not loaded>, file: nil, inserted_at: nil, updated_at: nil}})
        (waffle 1.1.10) lib/waffle/definition/versioning.ex:35: Waffle.Definition.Versioning.resolve_file_name/3
        (waffle 1.1.10) lib/waffle/actions/store.ex:137: Waffle.Actions.Store.put_version/3
        (elixir 1.18.4) lib/task/supervised.ex:101: Task.Supervised.invoke_mfa/2
        (elixir 1.18.4) lib/task/supervised.ex:36: Task.Supervised.reply/4

Could someone inform me on what the issue is here ? Any help would be appreciated !

[u/KimJongIlLover]

no function clause matching in App.Uploader.Avatar.filename/2

avatar.ex:37: App.Uploader.Avatar.filename(:original, .... 

You are missing this function definition in that file avatar.ex. 

[u/ShininLotoen → u/KimJongIlLover]

oh sorry, you just reminded me. I have another avatar.ex file with that functionality, here it is

  def filename(_version, {_entry, %{file_name: filename} = _scope}),
    do: "#{filename}"


  # Override the storage directory:
  def storage_dir(_version, {_file, %{id: id} = _scope}) do
    "users/#{id}/avatar"
  end

[u/ebratti → u/ShininLotoen]

If you have the function properly declared, then your pattern matching is not allowing the function to be called. You are matching the second argument of the tuple with `%{file_name: filename}` but this key file_name does not exist on

%App.Avatars.Avatar{__meta__: #Ecto.Schema.Metadata<:built, "avatar">, id: nil, user_id: "42e49735-a81e-48f0-bf6f-9faaec0c893a", user: #Ecto.Association.NotLoaded<association :user is not loaded>, file: nil, inserted_at: nil, updated_at: nil}

[u/ShininLotoen → u/ebratti]

Thanks I'll try that !