Undefined method `header_row?' for ["A", nil]:Array (NoMethodError)

7stud2 · 23 February 2014 18:10

Can anyone tell me why I am getting the error ?

require 'csv'

_output_file_path =
File.expand_path('output.csv',File.dirname(__FILE__))

hash = { 'A' => [ 'v', 'x', 'y' , 'z' ] ,
           'B' => [ 'm', 'n' , 'o' ] ,
           'C' => [ 'i', 'j' , 'k' , 'l', 'm', 'n' , 'o' ]
       }

headers = hash.keys
csv_row = CSV::Row.new(headers,[],true)
csv_table = CSV::Table.new(csv_row)

headers.each do |col_name|
csv_table[col_name] = hash[col_name]
end

p csv_table.to_csv
# ~> /home/kirti/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/csv.rb:726:in
`block in []=': undefined method `header_row?' for ["A", nil]:Array
(NoMethodError)
# ~> from
/home/kirti/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/csv.rb:504:in
`each'
# ~> from
/home/kirti/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/csv.rb:504:in
`each'
# ~> from
/home/kirti/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/csv.rb:725:in
`each_with_index'
# ~> from
/home/kirti/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/csv.rb:725:in `[]='
# ~> from -:16:in `block in <main>'
# ~> from -:15:in `each'
# ~> from -:15:in `<main>'

···

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7stud2 · 23 February 2014 19:14

I have fixed the error. But csv_table not showing any data .

require 'csv'

_output_file_path =
File.expand_path('output.csv',File.dirname(__FILE__))

hash = { 'A' => [ 'v', 'x', 'y' , 'z' ] ,
           'B' => [ 'm', 'n' , 'o' ] ,
           'C' => [ 'i', 'j' , 'k' , 'l', 'm', 'n' , 'o' ]
       }

headers = hash.keys
csv_row = CSV::Row.new(headers,[],true)
csv_table = CSV::Table.new([csv_row])
csv_table.delete(1)
headers.each do |col_name|
csv_table[col_name] = hash[col_name]
end
csv_table.to_csv
# => "A,B,C\n"

What wrong I did here ?

···

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abinoam · 25 February 2014 00:05

Dear Arup,

Look at Class: CSV::Table (Ruby 2.1.0)

"Columns are returned as an Array of values. Altering that Array has
no effect on the table."

headers.each do |col_name|
p csv_table[col_name].class # Add this line
csv_table[col_name] = hash[col_name]
end

And you will see:
Array
Array
Array

Abinoam Jr.

···

On Sun, Feb 23, 2014 at 4:14 PM, Arup Rakshit <lists@ruby-forum.com> wrote:

I have fixed the error. But csv_table not showing any data .

require 'csv'

_output_file_path =
File.expand_path('output.csv',File.dirname(__FILE__))

hash = { 'A' => [ 'v', 'x', 'y' , 'z' ] ,
           'B' => [ 'm', 'n' , 'o' ] ,
           'C' => [ 'i', 'j' , 'k' , 'l', 'm', 'n' , 'o' ]
       }

headers = hash.keys
csv_row = CSV::Row.new(headers,,true)
csv_table = CSV::Table.new([csv_row])
csv_table.delete(1)
headers.each do |col_name|
  csv_table[col_name] = hash[col_name]
end
csv_table.to_csv
# => "A,B,C\n"

What wrong I did here ?

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7stud2 · 25 February 2014 08:09

Abinoam Jr. wrote in post #1137892:

Dear Arup,

Look at
Class: CSV::Table (Ruby 2.1.0)

"Columns are returned as an Array of values. Altering that Array has
no effect on the table."

But I am using the method `#=`
(Class: CSV::Table (Ruby 2.1.0)
) not `#`.

In the default mixed mode, this method **assigns rows for index access
and columns for header access.**

···

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7stud2 · 25 February 2014 08:09