How to read CSV with headers?
Ruby provides a way to read a CSV file. We can specify options to let Ruby know if the file has headers or not.
How to read a CSV file with headers
| name | age |
|---|---|
| Alice | 30 |
| Bob | 25 |
Passing headers: true option will treat the first row as headers.
We can now access the values using the header names.
require 'csv'
CSV.foreach("path/to/file.csv", headers: true) do |row|
p row
p row['name']
p row['age']
end
# => #<CSV::Row "name":"Alice" "age":"30">
# => "Alice"
# => "30"
# => #<CSV::Row "name":"Bob" "age":"25">
# => "Bob"
# => "25"
We can also use various header_converters to convert the headers to a different format.
Convert headers to downcase
Passing downcase to header_converters will convert the headers to lowercase.
| Name | Age |
|---|---|
| Alice | 30 |
| Bob | 25 |
require 'csv'
CSV.foreach("path/to/file.csv", headers: true, header_converters: :downcase) do |row|
p row
p row['name']
p row['age']
end
# => #<CSV::Row "name":"Alice" "age":"30">
# => "Alice"
# => "30"
# ...
Convert headers to symbol
Passing symbol to header_converters will convert the headers to symbols.
| First Name | Age |
|---|---|
| Alice | 30 |
| Bob | 25 |
Note: This tokenizes the header names and converts them to symbols. "First Name" becomes :first_name.
require 'csv'
CSV.foreach("path/to/file.csv", headers: true, header_converters: :symbol) do |row|
p row
p row[:first_name]
p row[:age]
end
# => #<CSV::Row first_name:"Alice" age:"30">
# => "Alice"
# => "30"
# ...