Palindrome
Hi there,
I’ve got the following function to read from a CSV file and insert the data into the address table of my database.
def process_csv_file(%User{type: "customer"} = customer, file) do
File.stream!(file)
|> Stream.map(& &1)
|> CSV.decode(separator: ?;, headers: false)
|> Stream.map(fn x ->
case x do
{:ok, [name, address, zip_code, city, country]} ->
create_address(customer, %{
name: name,
address_one: address,
zip_code: zip_code,
city: city,
country: country
})
_ ->
IO.puts("Something went wrong...")
end
end)
|> Stream.run()
end
If I try to run it, it returns :ok and nothing happens.
But if I use Enum instead of Stream, everything runs fine. What am I doing wrong here? ![]()
(In this case it isn’t very important, it’s just a small file. But I’m hoping to learn something from this.)
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kelvinst
Taking the answer from the docs for
Stream.run/1:One might prefer
Stream.runoverEnum.mapwhen the expected result of the stream iterations is the side effect itself, so it does not have to return any value, and in that case, it would just discard the iteration results, which might be more efficient for most cases (like the example the docs gave).That’s not the case for your function there, as far as I understand, as you want to process a CSV and return a list of addresses from it.
Last Post!
kelvinst
I see, so you don’t want the actual list of new addresses then? AFAIK it should work with
Stream.run()then. When you say “nothing happens” you mean the addresses are not being created?