Merge 9b1705f into 11ae60b

.gitignore

@@ -6,8 +6,5 @@
 /doc/
 /pkg/
 /spec/reports/
-/tmp/
-*output.csv
-*input.csv
-*result.csv
-*transformed.csv
+tmp/*
+!tmp/

.travis.yml

@@ -2,9 +2,9 @@ sudo: false
 language: ruby
 cache: bundler
 rvm:
+  - 2.0.0
   - 2.1.0
   - 2.2.0
-  - 2.2.2
   - 2.3.0
-  - 2.3.3
-before_install: gem install bundler -v 1.13.6
+  - 2.4.0
+  - 2.5.0

README.md

@@ -46,20 +46,20 @@ The headers will be picked up and used instead of the first line.
 
 These are the settings that will be merged with settings passed through either `SimpleCsv#generate` or `SimpleCsv#read`
 
-|        setting       |                   value               |
-|----------------------|---------------------------------------|
-|`:col_sep`            | `","`                                 |
-|`:row_sep`            | `:auto`                               |
-|`:quote_char`         | `"\"`                                 |
-|`:field_size_limit`    | `nil`                                 |
-|`:converters`         | `[:all, :blank_to_nil, :null_to_nil]` |
-|`:unconverted_fields`  | `nil`                                 |
-|`:headers`            | `true`                                |
-|`:return_headers`     | `false`                               |
-|`:header_converters`  | `nil`                                 |
-|`:skip_blanks`        | `false`                               |
-|`:force_quotes`       | `true`                                |
-|`:skip_lines`         | `nil`                                 |
+| setting                | value                                   |
+| ---------------------- | --------------------------------------- |
+| `:col_sep`             | `","`                                   |
+| `:row_sep`             | `:auto`                                 |
+| `:quote_char`          | `"\"`                                   |
+| `:field_size_limit`    | `nil`                                   |
+| `:converters`          | `[:all, :blank_to_nil, :null_to_nil]`   |
+| `:unconverted_fields`  | `nil`                                   |
+| `:headers`             | `true`                                  |
+| `:return_headers`      | `false`                                 |
+| `:header_converters`   | `nil`                                   |
+| `:skip_blanks`         | `false`                                 |
+| `:force_quotes`        | `true`                                  |
+| `:skip_lines`          | `nil`                                   |
 
 The following settings differ from the `CSV::DEFAULT_OPTIONS`
 
@@ -110,7 +110,12 @@ SimpleCsv.generate path, options = { ... }, &block
 The `SimpleCsv#generate` method takes a (required) path, an (optional) hash of options and a (required) block to start building a CSV file.
 To generate a CSV file we use `SimpleCsv#generate` (using the [faker](https://github.com/stympy/faker) gem to provide fake data)
 
-While writing a row to a CSV, the value of a set property can be accessed by calling that property method again without arguments. (See the "inspect a value" comment in the following example)
+This method passes any unknown method to its caller (`main Object` if none). If you need a reference to the instance of the current writer from within the block, it takes an optional argument:
+
+```ruby
+```
+
+While writing a row to a CSV, the value of a set property can be accessed by calling that property method again without arguments (See the "inspect a value" comment in the following example).
 
 ```ruby
 require 'faker'
@@ -156,7 +161,7 @@ end
 
 ### Reading a CSV file without headers
 
-Last but not least, if we have a CSV file that does not contain headers we can use the following setup.
+If we have a CSV file that does not contain headers we can use the following setup.
 Setting `:has_headers` to `false` means we do not expect the first line to be headers.
 Therefore we have to explicitly define the headers before looping the CSV.
 
@@ -172,6 +177,34 @@ SimpleCsv.read('headerless.csv', has_headers: false) do
 end
 ```
 
+### Transforming s CSV file
+
+When you want to alter or reduce the output of a given CSV file, `SimpleCsv#transform` can be used.
+This allows you to apply call a block for each value in a specified column, you can also control the output headers to remove clutter from the input file.
+
+A transformation is defined by calling the header you wish to modify with a block that performs the modification.
+In below example, a CSV with columns `:name`, `:username`, `:age` and `:interests` is assumed. The `:age` of every row
+will be incremented because `age` was defined with the block. **Only** `headers` _and_ `output_headers` are supported within the transform block.
+
+```ruby
+SimpleCsv.transform('people.csv', output: 'people2.csv') do
+  # define specific output headers, other columns will not be added to output csv file
+  output_headers :name, :username, :age, :interests
+
+  # everyone got one year older, increase all ages.
+  age { |n| n + 1 }
+
+  # replace all names with "#{name}_old".
+  name { |s| "#{name}_old" }
+end
+```
+
+The above example will create a file called `people2.csv` that contains the result data. The original file is **not** destroyed by default.
+There is one additional option for `SimpleCsv#transform` which is the `:output` option.
+When this option not set, the returned file will have the same name as the input CSV followed by a timestamp
+formatted in the following format: `[input_csv]-[%d-%m-%Y-%S&7N].csv` (`[input_csv]` will have `.csv` extension stripped and reapplied).
+See Ruby's [`Time#strftime`](https://ruby-doc.org/core-2.5.0/Time.html) documentation for more information.
+
 ### Batch operations
 
 If we have a large CSV we might want to batch operations (say, if we are inserting this data into a database or through an API).

bin/console

@@ -5,21 +5,25 @@ require 'pry'
 require 'faker'
 require 'simple_csv'
 
-SimpleCsv.generate('sample.csv') do
-  headers :name, :age
+# SimpleCsv.generate('sample.csv') do
+#   headers :name, :age
 
-  10.times do
-    name Faker::Name.name
-    age  Faker::Number.between(20, 120)
-  end
-end
+#   10.times do
+#     name Faker::Name.name
+#     age  Faker::Number.between(20, 120)
+#   end
+# end
 
-SimpleCsv.transform('sample.csv', output: 'result.csv') do
-  output_headers :age
+SimpleCsv.transform('spec/files/result.csv', output: 'result.csv') do
+  output_headers 'user name'
 
-  age { |n| n * 2 }
+  user_name { |n| n * 2 }
 end
 
 SimpleCsv.read('result.csv') do
   p headers
+
+  each_row do
+    p headers.map { |h| send(h) }
+  end
 end

lib/simple_csv/base.rb

@@ -42,14 +42,13 @@ def first_line
       @first_line ||= File.open @csv_path, &:readline
     end
 
-
     def headers?
       @headers_set
     end
 
-    def alias_to_friendly_headers
+    def alias_to_friendly_headers(names = @headers)
       @col_map ||= {}
-      aliasses = headers.each_with_object({}) do |hdr, h|
+      aliasses = names.each_with_object({}) do |hdr, h|
         n = hdr.to_s.strip.gsub(/([a-z])([A-Z])/, '\1_\2').downcase
                .gsub(/[^\w]|\s/, '_')
         h[n] = hdr unless @col_map.key? n

lib/simple_csv/transformer.rb

@@ -22,13 +22,14 @@ def output_headers(*out_headers)
       return @output_headers if @output_headers.any?
 
       @output_headers = out_headers.map(&:to_s)
+      alias_to_friendly_headers @output_headers
+      @output_headers
     end
 
     private
 
     def apply_transforms(path, **opts)
       received_headers = headers
-      transformations  = @transforms
       timestamp        = Time.new.strftime '%d-%m-%Y-%S%7N'
       output_path      = opts.delete(:output) || "#{path.split('.')[0..-2].join}-#{timestamp}.csv"
       output_headers   = @output_headers.any? ? @output_headers : received_headers
@@ -39,7 +40,7 @@ def apply_transforms(path, **opts)
 
           reader.each_row do
             output_headers.each do |column|
-              transform = transformations[column.to_sym]
+              transform = find_transform column
               result    = transform ? transform.call(reader.send(column))
                                     : reader.send(column)
 
@@ -50,8 +51,14 @@ def apply_transforms(path, **opts)
       end
     end
 
+    def find_transform(column)
+      @transforms[(@col_map.key(column.to_s) || column).to_sym]
+    end
+
     def method_missing(mtd, *args, &block)
-      if headers.include?(mtd.to_s) || @output_headers.include?(mtd.to_s)
+      mstr = mtd.to_s
+
+      if headers.include?(mstr) || @output_headers.include?(mstr) || @col_map.key?(mstr)
         @transforms[mtd] = block || args.first unless @transforms.key? mtd
       else
         @caller_self.send mtd, *args, &block

simple_csv.gemspec

@@ -24,9 +24,9 @@ Gem::Specification.new do |spec|
 
   spec.required_ruby_version = '>= 2.1'
 
-  spec.add_development_dependency 'bundler', '~> 1.13'
-  spec.add_development_dependency 'rake', '~> 10.0'
-  spec.add_development_dependency 'rspec', '~> 3.0'
+  spec.add_development_dependency 'bundler'
+  spec.add_development_dependency 'rake'
+  spec.add_development_dependency 'rspec'
   spec.add_development_dependency 'pry'
   spec.add_development_dependency 'pry-byebug'
   spec.add_development_dependency 'faker'