Phlex::CSV (#655)

In addition to HTML and SVG, Phlex will soon support CSVs.

This is all based on @willcosgrove’s explorations here
https://gist.github.com/willcosgrove/004389a5a053bccb35016223317cb9e9

---------

Co-authored-by: Will Cosgrove <[email protected]>

.rubocop.yml

@@ -14,6 +14,9 @@ Style/MixinUsage:
 Style/RedundantDoubleSplatHashBraces:
   Enabled: false
 
+Style/OptionalArguments:
+  Enabled: false
+
 Naming/AsciiIdentifiers:
   Enabled: false
 

lib/phlex.rb

@@ -14,6 +14,8 @@ module Phlex
 	autoload :Unbuffered, "phlex/unbuffered"
 	autoload :ConcurrentMap, "phlex/concurrent_map"
 	autoload :BlackHole, "phlex/black_hole"
+	autoload :CSV, "phlex/csv"
+	autoload :Callable, "phlex/callable"
 
 	# Included in all Phlex exceptions allowing you to match any Phlex error.
 	# @example Rescue any Phlex error:

lib/phlex/csv.rb

@@ -0,0 +1,93 @@
+# frozen_string_literal: true
+
+class Phlex::CSV
+	include Phlex::Callable
+
+	def initialize(collection)
+		@collection = collection
+		@_headers = []
+		@_current_row = []
+		@_current_column_index = 0
+		@_view_context = nil
+		@_first = true
+	end
+
+	attr_reader :collection
+
+	def call(buffer = +"", view_context: nil)
+		@_view_context = view_context
+
+		each_item do |record|
+			collection_yielder(record) do |*args, **kwargs|
+				view_template(*args, **kwargs)
+
+				if @_first && render_headers?
+					buffer << @_headers.map! { |value| escape(value) }.join(",") << "\n"
+				end
+
+				buffer << @_current_row.map! { |value| escape(value) }.join(",") << "\n"
+				@_current_column_index = 0
+				@_current_row.clear
+			end
+
+			@_first = false
+		end
+
+		buffer
+	end
+
+	def file_name
+		nil
+	end
+
+	def content_type
+		"text/csv"
+	end
+
+	private
+
+	def column(header = nil, value)
+		if @_first
+			@_headers << header
+		elsif header != @_headers[@_current_column_index]
+			raise "Inconsistent header."
+		end
+
+		@_current_row << value
+		@_current_column_index += 1
+	end
+
+	def each_item(&block)
+		collection.each(&block)
+	end
+
+	def collection_yielder(record)
+		yield(record)
+	end
+
+	def template(...)
+		nil
+	end
+
+	def render_headers?
+		true
+	end
+
+	def helpers
+		@_view_context
+	end
+
+	def render(renderable)
+		renderable.call(view_context: @_view_context)
+	end
+
+	def escape(value)
+		value = value.to_s
+
+		if value.include?('"') || value.include?(",") || value.include?("\n")
+			%("#{value.gsub('"', '""')}")
+		else
+			value
+		end
+	end
+end

lib/phlex/html.rb

@@ -49,6 +49,14 @@ def unbuffered
 			self.class.__unbuffered_class__.new(self)
 		end
 
+		def file_name
+			nil
+		end
+
+		def content_type
+			"text/html"
+		end
+
 		# This should be extended after all method definitions
 		extend ElementClobberingGuard
 	end

lib/phlex/svg.rb

@@ -8,5 +8,13 @@ class SVG < SGML
 
 		# This should be extended after all method definitions
 		extend ElementClobberingGuard
+
+		def content_type
+			"image/svg+xml"
+		end
+
+		def file_name
+			nil
+		end
 	end
 end

test/phlex/csv.rb

@@ -0,0 +1,77 @@
+# frozen_string_literal: true
+
+Product = Struct.new(:name, :price)
+
+class Example < Phlex::CSV
+	def view_template(product)
+		column("name", product.name)
+		column("price", product.price)
+	end
+end
+
+class ExampleWithoutHeaders < Example
+	def render_headers?
+		false
+	end
+end
+
+describe Phlex::CSV do
+	it "renders a CSV" do
+		products = [
+			Product.new("Apple", 1.00),
+			Product.new("Banana", 2.00)
+		]
+
+		csv = Example.new(products).call
+
+		expect(csv).to be == <<~CSV
+			name,price
+			Apple,1.0
+			Banana,2.0
+		CSV
+	end
+
+	it "escapes commas" do
+		product = Product.new("Apple, Inc.", 1.00)
+		csv = Example.new([product]).call
+
+		expect(csv).to be == <<~CSV
+			name,price
+			"Apple, Inc.",1.0
+		CSV
+	end
+
+	it "escapes newlines" do
+		product = Product.new("Apple\nInc.", 1.00)
+		csv = Example.new([product]).call
+
+		expect(csv).to be == <<~CSV
+			name,price
+			"Apple\nInc.",1.0
+		CSV
+	end
+
+	it "escapes quotes" do
+		product = Product.new("Apple\"Inc.", 1.00)
+		csv = Example.new([product]).call
+
+		expect(csv).to be == <<~CSV
+			name,price
+			"Apple""Inc.",1.0
+		CSV
+	end
+
+	it "renders without headers" do
+		products = [
+			Product.new("Apple", 1.00),
+			Product.new("Banana", 2.00)
+		]
+
+		csv = ExampleWithoutHeaders.new(products).call
+
+		expect(csv).to be == <<~CSV
+			Apple,1.0
+			Banana,2.0
+		CSV
+	end
+end