There’s no direct syntax for or in the middle of patterns but you can use a guard: case testvalue do n when n in [200, 400] -> true _ -> false end You can also use or in guards. This will work too but is more verbose: case testvalue do n when n == 200 … Read more
Mix.env() doesn’t work in production or other environments where you use compiled releases (built using Exrm / Distillery) or when Mix just isn’t available. The solution is to specify it in your config/config.exs file: config :your_app, env: Mix.env() You can then get the environment atom in your application like this: Application.get_env(:your_app, :env) #=> :prod Update … Read more
The error you get is from the underlying database where the column type is set to varchar which is what’s created by default when you specify the column type as string in a migration. To store a variable length string over 255 characters, you need to specify the column type as text in the migration. … Read more
I can think of 3 ways to quit an IEx shell: The mentioned <ctrl-c> hit twice or once followed by q and then <enter>, <ctrl-g> and then q + <enter>, and finally System.halt, but there is a difference between System.halt and the others. Namely that System.halt “halts the Erlang runtime” and the others just “quit … Read more
Use Enum.take/2 with a negative value: iex(1)> list = [1, 2, 4, 5, 6, 7, 8, 9, 9, 88, 88] iex(2)> Enum.take(list, -4) |> IO.inspect(charlists: :as_lists) [9, 9, 88, 88] take(enumerable, count) […] count must be an integer. If a negative count is given, the last count values will be taken. […]
You should use IO.inspect instead of IO.puts to print the internal representation of a value: iex> IO.puts [1, 2] ^A^B # prints “^A^B” :ok # return value of IO.puts iex> IO.inspect [1, 2] [1, 2] # prints “[1, 2]” [1, 2] # return value of IO.inspect However you might still get problems with some special … Read more
Not a direct answer, but another way to maybe achieve what you want: You could have a playground project that you generate once (e.g. mix new playground) and that you can then relatively easily add new dependencies to. If you do iex -S mix within this project, you’ll get all its dependencies. If you want … Read more
Updated Answer As José Valim said in his answer, in Elixir 1.1 and above, you can now use these methods to get random element(s) from a list: Enum.random/1 – For getting single random element Enum.take_random/2 – For getting multiple random elements Example: Enum.random(list) #=> 4 Enum.take_random(list, 3) #=> [3, 9, 1] Enum.take_random(list, 1) #=> [7] … Read more
I’m not sure when this was added to Ecto, but at least in 2.1.6 there’s no need for raw SQL anymore. drop/1 now supports constraints (drop_if_exists/1 doesn’t though): def up do drop constraint(:videos, “videos_user_id_fkey”) alter table(:videos) do modify :user_id, references(:users, on_delete: :delete_all) end end def down do drop constraint(:videos, “videos_user_id_fkey”) alter table(:videos) do modify :user_id, … Read more
Ecto’s queries rely on macros to provide the powerful DSL that we use. That means that, whatever comes after from, is not “regular” Elixir code, but a DSL which will eventually get transformed to SQL query. So, a caret there is not pin operator per se, and has nothing to do with pattern matching (although … Read more