Hey
I want to introduce you a small utility that may help in writing dynamic queries

In a few words, this code:

blank_string? = fn string -> String.trim(string) == "" end
query = some_complex_query()

query =
  if not is_binary(params[:some_field1]) or blank_string?.(params[:some_field1]) do
    query
  else
    query |> where(some_field1: ^params[:some_field1])
  end

query =
  if is_nil(params[:some_field2]) do
    query
  else
    query |> where(some_field2: ^params[:some_field2])
  end

query |> Repo.all()

can be reorganzied to this:

blank_string? = fn string -> String.trim(string) == "" end

some_complex_query()
|> Composite.new(params)
|> Composite.param(:somefield1, &where(&1, some_field1: ^&2),
  ignore?: &(not is_binary(&1) or blank_string?.(&1))
)
|> Composite.param(:some_field2, &where(&1, some_field2: ^&2))
|> Repo.all()

However, library can be used not only with Ecto.
For more complex example with joins check test file.

Currently, it is not published to hex and available only on Github

Any feedback is welcome!