CODEWITHSUNDEEP
elixir
Torito
Torito

Reputation: 315

Why error -- undefined function defstruct

I have this modules where I'm trying to define a struct:

defmodule A do
  defmodule B do
    defstruct :id, :name
  end
end

Why error?

undefined function defstruct/2

Why is this error?

Upvotes: 3

Views: 747

Answers (2)

PatNowak
PatNowak

Reputation: 5812

Just check the official documentation in that matter.

You can use notation without square brackets, but you have be explicit and provide a keyword list. In example there are default values provided.

In your case :id, :name won't be keyword list and that's why compiler throw an error that you put there two arguments.

If you would do:

defmodule A do
  defstruct id: nil, name: nil
end

It would works perfectly fine.

Otherwise use explicitly list.

Upvotes: 4

nietaki
nietaki

Reputation: 9018

Elixir interprets defstruct :id, :name as calling defstruct with 2 arguments, that's the /2 part in undefined function defstruct/2.

What you want to do is pass a single argument to defstruct, a list of field names:

defmodule A do
  defmodule B do
    defstruct [:id, :name]
  end
end

Upvotes: 5

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