CSV Import issue - ruby-on-rails

Question

I have this to parse a CSV file:
csv_file = CSV.parse(
file.read(),
headers: true,
header_converters: :symbol
)
It works, but I want to specify the encoding type so I add: {encoding: 'UTF-8'} into the read method as below:
csv_file = CSV.parse(
file.read({encoding: 'UTF-8'}),
headers: true,
header_converters: :symbol
)
But I get this error: can't convert Hash into Integer
I just can't see what is wrong. I have checked the docs but it says you can pass the encoding in like so but it does need the file as the first argument so it could be stalling there but surely as it already knows what file is is reading it should be ok.
How can I solve this?
Update:
I have updated to the following:
def import
if params[:import_coasters]
file = params[:import_coasters][:file]
Park.import_from_csv(file)
def self.import_from_csv(file)
Park.destroy_all
and
csv_file = CSV.parse(
File.read(file, {encoding: 'UTF-8'}),
headers: true,
header_converters: :symbol
)
But I get the following error:
can't convert ActionDispatch::Http::UploadedFile into String

Answer 1

You're close. Try this:
# Step 1: convert the uploaded file object to a file name
uploaded_file = params[:import_coasters][:file]
file_name = uploaded_file.path
# Step 2: To get the input text and see if it's what you expect
text = File.read(
file_name,
{encoding: 'UTF-8'}
)
# Parse the text
csv_file = CSV.parse(
text,
headers: true,
header_converters: :symbol
)
From the Ruby 1.9.3 docs on IO.read:
"If the last argument is a hash, it specifies option for internal open(). The key would be the following. open_args: is exclusive to others."
http://www.ruby-doc.org/core-1.9.3/IO.html#method-c-read
Also, look at the documentation for UploadedFile because it's not actually a typical Ruby File object:
http://api.rubyonrails.org/classes/ActionDispatch/Http/UploadedFile.html

Answer 2

It is because File.read() expect a filename as the first argument. You are passing ActionDispatch::Http::UploadedFile instead. If you look at the documentation, you'll see that UploadedFile already has a read method, so you can try:
csv_file = CSV.parse(
file.read({encoding: 'UTF-8'}),
headers: true,
header_converters: :symbol
)