fix unsafe variable assignment in case statement

Question

So I know it aint right to assign a variable inside a case statement, but I can't figure out how to refactor this so that the user gets redirected AND the conn gets assigned correctly:

case Repo.insert(changeset) do
  {:ok,user} ->  conn = put_session(conn, :user, user)
                 redirect conn, to: "/"
  {:error, changeset} -> render(conn,"sign_up.html", changeset: changeset, referral: referral)
end

I can't just move the conn out can I? I'm not sure that assigns it right since now I'm assigning it to the whole redirect statement.

conn =
case Repo.insert(changeset) do
  {:ok,user} -> redirect put_session(conn, :user, user), to: "/"
  {:error, changeset} -> render(conn,"sign_up.html", changeset: changeset, referral: referral)
end

Any suggestions?

score 2 · Accepted Answer · answered Jun 02 '17 at 05:00

2

redirect and render both return the conn so the second version is fine.

If the case is the last expression in the controller function, then you might not need to re-assign conn at all.

conn =
  case Repo.insert(changeset) do
    {:ok,user} -> 
      conn
      |> put_session(conn, :user, user)
      |> redirect(to: "/")

    {:error, changeset} -> 
      conn
      |> render("sign_up.html", changeset: changeset, referral: referral)
  end

answered Jun 02 '17 at 05:00

Mike Buhot

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BTW, the first one is fine as well. – Aleksei Matiushkin Jun 02 '17 at 06:16
depends if conn is used after the case, since it is conditionally rebound in the first case arm. – Mike Buhot Jun 02 '17 at 11:23
It does not matter, it is rebound with put_session, and the returned value is still redirect. – Aleksei Matiushkin Jun 02 '17 at 11:32
The concern is that conn is being conditionally rebound inside a case. This generates a warning and will be an error in future Elixir releases iirc. – Mike Buhot Jun 03 '17 at 12:07

fix unsafe variable assignment in case statement

1 Answers1