Adding SmarterCSV.generate; improve behavior of Writer class (#280)

Author: tilo

CHANGELOG.md

@@ -1,6 +1,10 @@
 
 # SmarterCSV 1.x Change Log
 
+## 1.11.1 (2024-07-05)
+  * improved behavior of Writer class
+  * added SmarterCSV.generate shortcut for CSV writing
+    
 ## 1.11.0 (2024-07-02)
   * added SmarterCSV::Writer to output CSV files ([issue #44](https://github.com/tilo/smarter_csv/issues/44))
 

lib/smarter_csv.rb

@@ -1,6 +1,8 @@
 # frozen_string_literal: true
 
 require "smarter_csv/version"
+require "smarter_csv/errors"
+
 require "smarter_csv/file_io"
 require "smarter_csv/options_processing"
 require "smarter_csv/auto_detection"
@@ -9,8 +11,10 @@
 require 'smarter_csv/header_validations'
 require "smarter_csv/headers"
 require "smarter_csv/hash_transformations"
+
 require "smarter_csv/parse"
 require "smarter_csv/writer"
+require "smarter_csv/smarter_csv"
 
 # load the C-extension:
 case RUBY_ENGINE
@@ -49,4 +53,24 @@
   BLOCK_COMMENT
 end
 # :nocov:
-require "smarter_csv/smarter_csv"
+
+module SmarterCSV
+  # SmarterCSV.generate(filename, options) do |csv_writer|
+  #   MyModel.find_in_batches(batch_size: 100) do |batch|
+  #    batch.pluck(:name, :description, :instructor).each do |record|
+  #       csv_writer << record
+  #     end
+  #   end
+  # end
+  #
+  # rubocop:disable Lint/UnusedMethodArgument
+  def self.generate(filename, options = {}, &block)
+    raise unless block_given?
+
+    writer = Writer.new(filename, options)
+    yield writer
+  ensure
+    writer.finalize
+  end
+  # rubocop:enable Lint/UnusedMethodArgument
+end

lib/smarter_csv/smarter_csv.rb

@@ -1,15 +1,6 @@
 # frozen_string_literal: true
 
 module SmarterCSV
-  class SmarterCSVException < StandardError; end
-  class HeaderSizeMismatch < SmarterCSVException; end
-  class IncorrectOption < SmarterCSVException; end
-  class ValidationError < SmarterCSVException; end
-  class DuplicateHeaders < SmarterCSVException; end
-  class MissingKeys < SmarterCSVException; end # previously known as MissingHeaders
-  class NoColSepDetected < SmarterCSVException; end
-  class KeyMappingError < SmarterCSVException; end
-
   # first parameter: filename or input object which responds to readline method
   def SmarterCSV.process(input, given_options = {}, &block) # rubocop:disable Lint/UnusedMethodArgument
     initialize_variables

lib/smarter_csv/version.rb

@@ -1,5 +1,5 @@
 # frozen_string_literal: true
 
 module SmarterCSV
-  VERSION = "1.11.0"
+  VERSION = "1.11.1"
 end

lib/smarter_csv/writer.rb

@@ -35,22 +35,35 @@ module SmarterCSV
   #    Make sure to use the correct form when specifying headers manually,
   #    in combination with the :discover_headers option
 
+  attr_reader :options, :row_sep, :col_sep, :quote_char, :force_quotes, :discover_headers, :headers, :map_headers, :output_file
+
   class Writer
     def initialize(file_path, options = {})
       @options = options
-      @discover_headers = options.has_key?(:discover_headers) ? (options[:discover_headers] == true) : true
-      @headers = options[:headers] || []
       @row_sep = options[:row_sep] || "\n" # RFC4180 "\r\n"
       @col_sep = options[:col_sep] || ','
-      @quote_char = '"'
+      @quote_char = options[:quote_char] || '"'
       @force_quotes = options[:force_quotes] == true
+      @discover_headers = true # defaults to true
+      if options.has_key?(:discover_headers)
+        # passing in the option overrides the default behavior
+        @discover_headers = options[:discover_headers] == true
+      else
+        # disable discover_headers when headers are given explicitly
+        @discover_headers = !(options.has_key?(:map_headers) || options.has_key?(:headers))
+      end
+      @headers = [] # start with empty headers
+      @headers = options[:headers] if options.has_key?(:headers) # unless explicitly given
+      @headers = options[:map_headers].keys if options.has_key?(:map_headers) && !options.has_key?(:headers)
       @map_headers = options[:map_headers] || {}
+
       @output_file = File.open(file_path, 'w+')
       # hidden state:
       @temp_file = Tempfile.new('tempfile', '/tmp')
       @quote_regex = Regexp.union(@col_sep, @row_sep, @quote_char)
     end
 
+    # this can be called many times in order to append lines to the csv file
     def <<(data)
       case data
       when Hash
@@ -60,7 +73,7 @@ def <<(data)
       when NilClass
         # ignore
       else
-        raise ArgumentError, "Invalid data type: #{data.class}. Must be a Hash or an Array."
+        raise InvalidInputData, "Invalid data type: #{data.class}. Must be a Hash or an Array."
       end
     end
 

spec/smarter_csv/writer_spec.rb

@@ -90,14 +90,31 @@
       expect(output).to include("Alex,,,USA,\n")
     end
 
-    context "when discover_headers is turned off" do
-      let(:options) { {discover_headers: false, headers: [:name, :country]} }
+    context "when headers are given explicitly" do
+      let(:options) { {headers: [:country, :name]} }
 
       it 'writes the given headers and data correctly' do
         create_csv_file
+
+        output = File.read(file_path)
+
+        expect(output).to include("country,name\n")
+        expect(output).to include(",John\n")
+        expect(output).to include("USA,Jane\n")
+        expect(output).to include(",Mike\n")
+        expect(output).to include("USA,Alex\n")
+      end
+    end
+
+    context "when map_headers is given explicitly" do
+      let(:options) { {map_headers: {name: "Person", country: "Country"}} }
+
+      it 'writes the given headers and data correctly' do
+        create_csv_file
+
         output = File.read(file_path)
 
-        expect(output).to include("name,country\n")
+        expect(output).to include("Person,Country\n")
         expect(output).to include("John,\n")
         expect(output).to include("Jane,USA\n")
         expect(output).to include("Mike,\n")
@@ -106,18 +123,18 @@
     end
   end
 
-  context 'when headers are given in advance' do
+  context 'when headers are given explicitly' do
     let(:options) { { headers: %i[name age city] } }
 
     it 'writes the given headers and data correctly' do
       create_csv_file
       output = File.read(file_path)
 
-      expect(output).to include("name,age,city,country,state\n")
+      expect(output).to include("name,age,city\n")
       expect(output).to include("John,30,New York\n")
-      expect(output).to include("Jane,25,,USA\n")
-      expect(output).to include("Mike,35,Chicago,,IL\n")
-      expect(output).to include("Alex,,,USA,\n")
+      expect(output).to include("Jane,25,\n")
+      expect(output).to include("Mike,35,Chicago\n")
+      expect(output).to include("Alex,,\n")
     end
   end
 
@@ -142,20 +159,22 @@
           name: 'Full Name',
           age: 'Age',
           city: 'City',
-          country: 'Country',
           state: 'State',
+          country: 'Country',
         }
       }
     end
 
-    it 'writes the mapped headers and data correctly' do
+    it 'writes the mapped headers and data in the correct order' do
       create_csv_file
+
       output = File.read(file_path)
 
-      expect(output).to include("Full Name,Age,City,Country,State\n")
-      expect(output).to include("John,30,New York\n")
-      expect(output).to include("Jane,25,,USA\n")
-      expect(output).to include("Mike,35,Chicago,,IL\n")
+      expect(output).to include("Full Name,Age,City,State,Country\n")
+      expect(output).to include("John,30,New York,,\n")
+      expect(output).to include("Jane,25,,,USA\n")
+      expect(output).to include("Mike,35,Chicago,IL,\n")
+      expect(output).to include("Alex,,,,USA\n")
     end
   end
 
@@ -194,15 +213,6 @@
       expect(output).to include("5,,,4\n")
     end
 
-    it 'appends with existing headers' do
-      options = { headers: [:a] }
-      writer = SmarterCSV::Writer.new(file_path, options)
-      writer << [{ a: 1, b: 2 }]
-      writer.finalize
-
-      expect(File.read(file_path)).to eq("a,b\n1,2\n")
-    end
-
     it 'appends with missing fields' do
       writer = SmarterCSV::Writer.new(file_path)
       writer << [{ a: 1, b: 2 }, { a: 3 }]
@@ -293,6 +303,13 @@
   end
 
   context 'Error Handling' do
+    it 'raises an error for invalid input data' do
+      expect do
+        writer = SmarterCSV::Writer.new(file_path)
+        writer << "this is invalid"
+      end.to raise_error SmarterCSV::InvalidInputData
+    end
+
     it 'handles file access issues' do
       allow(File).to receive(:open).and_raise(Errno::EACCES)