@rossta, @vidalraphael, @kelvinst

Thank you very much… I have learned new things here today… I am happy that I have found my way back to this forum after some bad bi yearly banning experiences at holy stackoverflow (latest only because I asked a duplicate question)…

I’m often lazy and just put a case between things… >.>

value
|> something(42)
|> something_else()
|> case do
     page where limit_size == nil -> page
     page -> page |> limit(size)
   end
|> some_more_things()
...

Also you really need to use code tags instead of quotes for bodies of code, you do it like:
```elixir
Code goes here like 2+2
```
Makes:

Code goes here like 2+2

As a possible alternative to writing a full fledged maybe_* function, you can also consider to use a general purpose maybe_if/3 function. I’ve done that in the past when I needed to chain multiple optional steps.

initial_data
|> first_transformation()
|> maybe_if(should_apply_step2, &second_transformation/1)
|> maybe_if(should_apply_step3, &third_transformation_with_params(&1, my_param))
|> another_one()

where maybe_if is defined like this:

def maybe_if(data, true, action)
  when is_function(action, 1),
  do: apply(action, data)

def maybe_if(data, false, _action), do: data

Actually, you should never assign variables inside conditionals like if, case and so on.

Instead of writing:

if is_list(params["policy"]["client_id"]) do
  page = page |> where([p, c], p.client_id in ^params["policy"]["client_id"])
end

You should write:

page = 
  if is_list(params["policy"]["client_id"]) do
    page |> where([p, c], p.client_id in ^params["policy"]["client_id"])
  else
    page
  end

Other than that I think it’s a good solution, but you could also take a look at Ecto’s 2.1 new dynamic expressions: https://github.com/elixir-ecto/ecto/blob/v2.1/CHANGELOG.md

Yep! @rossta thank you! That’s the way to go!