elixir - how to add conditional pipe into pipeline?

elixir ecto
asiniy picture asiniy · May 7, 2016 · Viewed 7.9k times · Source

I have a small pipeline in elixir, it's about changing ecto model state:

model
|> cast(params, ~w(something), ~w())
|> conditional
|> Repo.update

The problem is that I have conditional pipe which can be nil sometimes, so in the case it's nil it should do nothing and can works (I presume it will be fn(x) -> x end)

So, my question is: "how can I do that"?

Answer

NoDisplayName picture NoDisplayName · May 7, 2016 
model
|> cast(params, ~w(something), ~w())
|> maybe_do_something(conditional)
|> Repo.update

defp maybe_do_something(changeset, nil), do: changeset

defp maybe_do_something(changeset, func) do
  # Do something with changeset
end

Not sure if I got your question right, but maybe thats what you are looking for.

Related questions

Turn postgres date representation into ISO 8601 string

I'm trying to format a Postgres date representation into a ISO 8601 string. I'm assuming that there is a Postgres function that can do it, but I found the documentation short on examples. My query is SELECT now()::timestamp which returns [{{2016, 8, 9}, {3, 56, 55, 754181}}] …

Read More
How to use raw sql with ecto Repo

I have an upsert requirement, so I need to call a postgres stored procedure or use a common table expression. I also use the pgcrypto exgtension for passwords and would like to use postgres functions (such as "crypt" to encode/…

Read More
Is there a Phoenix equivalent to Rails Console

I'm just learning Phoenix and Elixir and I'm coming from Ruby/Rails where I work in the REPL using pry to inspect my database and application state. I'm trying to figure out how to interact with my database and models …

Read More