解析原始CSV

Question

我想添加新列并更新CSV响应中的现有值。如何进行以下转换的更简单更好的方法？

输入

id,name,country
1,John,US
2,Jack,UK
3,Sam,UK

我正在使用以下方法解析csv字符串并添加新列

# Parse original CSV
rows = CSV.parse(csv_string, headers: true).collect do |row|
  hash = row.to_hash
  # Merge additional data as a hash.
  hash.merge('email' => 'sample@gmail.com')
end

# Extract column names from first row of data
column_names = rows.first.keys
# Generate CSV after transformation of csv
csv_response = CSV.generate do |csv|
  csv << column_names
  rows.each do |row|
    # Extract values for row of data
    csv << row.values_at(*column_names)
  end
end

我正在使用以下方法解析csv并更新现有值

name_hash = {“ John” =>“ Johnny”，“ Jack” =>“ Jackie”}

解析原始CSV

rows = CSV.parse(csv_string, headers: true).collect do |row|
  hash = row.to_hash
  hash['name'] = name_hash[hash['name']] if name_hash[hash['name']] != nil
  hash
end

# Extract column names from first row of data
column_names = rows.first.keys
# Generate CSV after transformation of csv
csv_response = CSV.generate do |csv|
  csv << column_names
  rows.each do |row|
    # Extract values for row of data
    csv << row.values_at(*column_names)
  end
end

Answer 1

给出了以下用于修改表格的参考数据的一个可能选项：

name_hash = {"John" => "Johnny", "Jack" => "Jackie"}
sample_email = {'email' => 'sample@gmail.com'}

只需将转换为哈希的表存储在行中即可

rows = CSV.parse(csv_string, headers: true).map(&:to_h)
#=> [{"id"=>"1", "name"=>"John", "country"=>"US"}, {"id"=>"2", "name"=>"Jack", "country"=>"UK"}, {"id"=>"3", "name"=>"Sam", "country"=>"UK"}]

然后根据参考数据修改哈希（对于Ruby 2.6.1，我使用Object#then作为Ruby 2.5的别名，对于Ruby 2.5，我使用了Object#yield_self的别名）：

rows.each { |h| h.merge!(sample_email).then {|h| h['name'] = name_hash[h['name']] if name_hash[h['name']] } }
#=> [{"id"=>"1", "name"=>"Johnny", "country"=>"US", "email"=>"sample@gmail.com"}, {"id"=>"2", "name"=>"Jackie", "country"=>"UK", "email"=>"sample@gmail.com"}, {"id"=>"3", "name"=>"Sam", "country"=>"UK", "email"=>"sample@gmail.com"}]

最后还原表：

csv_response = CSV.generate(headers: rows.first.keys) { |csv| rows.map(&:values).each { |v| csv << v } }

所以您现在拥有：

puts csv_response

# id,name,country,email
# 1,Johnny,US,sample@gmail.com
# 2,Jackie,UK,sample@gmail.com
# 3,Sam,UK,sample@gmail.com

如何在Rails的CSV字符串中添加新列

解析原始CSV

1 个答案: