Equivalent of IO.inspect function that just returns string instead of printing given list, map or keyword list?
inspect([name: “John Doe”]) It is defined by the Kernel module and therefore automatically imported.
elixir
Return statement in Elixir
This is an interesting problem because you need to perform multiple checks, exit early, and in the process transform some state (connection). I typically approach this problem as follows: I implement each check as a function which takes state as an input and returns {:ok, new_state} or {:error, reason}. Then, I build a generic function … Read more
List comprehension with counter in Elixir
Use Enum.with_index: iex(1)> for {value, index} <- Enum.with_index([“a”, “b”]), do: {value, index} [{“a”, 0}, {“b”, 1}]
Can I concatenate strings in Elixir and use the pipe operator?
Yes, you can, by passing the full path to the function, which in this case is Kernel.<>: iex(1)> “foo” |> Kernel.<>(“bar”) “foobar”
Many to Many relationship in Ecto
This is an old question and the previously accepted answer was no longer the de facto way. Ecto now supports HABTM or many to many associations. https://hexdocs.pm/ecto/Ecto.Schema.html#many_to_many/3 many_to_many :users, MyApp.User, join_through: “chat_group_users”
using a package locally with hex.pm
Yes it is. In your mix.exs, you can list the dependency with the :path keyword (very similarly to what you do with gems). def dependencies do [{:testing_dep, path: “/Users/me/testing_dep”}] end You can read a list of all the supported options (e.g., pulling the dependency from GitHub or from a Git repository) in the documentation for … Read more
Loop through a Map’s key-value pairs
Turns out you iterate over a Map exactly like you do over a Keyword List (i.e. you use a tuple): Enum.each(%{a: 1, b: 2, c: 3}, fn {k, v} -> IO.puts(“#{k} –> #{v}”) end) Comprehensions also work: for {k, v} <- %{a: 1, b: 2, c: 3} do IO.puts(“#{k} –> #{v}”) end Note: If you … Read more
Count the Number of Entries in an Ecto Repository
The options that Dogbert has provided are both correct and should be used for Ecto 1.x. In Ecto 2.0 you can use Repo.aggregate/4 Repo.aggregate(Post, :count, :id)
Installing dependencies in Elixir
If you are looking for something similar to npm install –save, then this does not exist in Elixir. You install things by adding them to deps: in the mix.exs file in your project then running mix deps.get. The other way you may wish to install certain applications is via a mix archive allowing this mix … Read more