Module: CopyCsv::ClassMethods

Defined in:
lib/copy_csv.rb

Instance Method Summary collapse

Instance Method Details

#copy_csv(io, relation: all) ⇒ Object

Performs a database query to copy results as CSV to an IO object.

CSV is created directly in PostgreSQL with less overhead then written to the provided IO object.

Example

File.open("unsubscribed_users.csv", "w") do |file|
  User.where(unsubscribed: false).copy_csv(file)
end

Returns nil



19
20
21
22
23
24
25
26
27
28
29
30
31
32
 
# File 'lib/copy_csv.rb', line 19

def copy_csv(io, relation: all)
  query = <<-SQL
    COPY (#{ relation.to_sql }) TO STDOUT WITH DELIMITER ',' CSV HEADER ENCODING 'UTF-8' QUOTE '"'
  SQL

  raw = connection.raw_connection
  raw.copy_data(query) do
    while (row = raw.get_copy_data)
      io.puts(ensure_utf8(row))
    end
  end

  nil
end

#write_to_csv(file_name, mode = "w") ⇒ Object

Opens the file provided and writes the relation to it as a CSV.

Example

User.where(unsubscribed: false).write_to_csv("unsubscribed_users.csv")

Returns nil



41
42
43
44
45
 
# File 'lib/copy_csv.rb', line 41

def write_to_csv(file_name, mode = "w")
  File.open(file_name, mode) do |file|
    all.copy_csv(file)
  end
end