Feature/multiple header rows

README.rdoc

@@ -14,6 +14,7 @@ It is (very slightly) oriented towards exporting ActiveRecord sets, but it can b
   @users.to_xls(:columns => [:name, :role]) # include only these columns, on this order
   @users.to_xls(:columns => [:name, {:company => [:name, :address]}]) # able to pick associations/called methods
   @users.to_xls(:columns => [:name, {:company => [:name, :address]}], :headers => ['Name', 'Company', 'Address']) # provide better names for the associated columns
+  @users.to_xls(:columns => [:name, {:company => [:name, :address]}], :headers => [['Personal', 'Company'], ['Name', 'Name', 'Address']], :multiple_header_rows => true) # use multiple rows of headers
 
 == Format
 

lib/to_xls/writer.rb

@@ -35,10 +35,15 @@ def write_sheet(sheet)
       if columns.any?
         row_index = 0
 
-        if headers_should_be_included?
-          apply_format_to_row(sheet.row(0), @header_format)
-          fill_row(sheet.row(0), headers)
-          row_index = 1
+
+        if multiple_header_rows_should_be_included?
+          headers.each do |header_row|
+            fill_headers(sheet, header_row, row_index)
+            row_index += 1
+          end
+        elsif headers_should_be_included?
+          fill_headers(sheet, headers, row_index)
+          row_index += 1
         end
 
         @array.each do |model|
@@ -79,6 +84,13 @@ def headers_should_be_included?
       @options[:headers] != false
     end
 
+    def multiple_header_rows_should_be_included?
+      return false unless headers_should_be_included? && @options[:multiple_header_rows] && @options[:headers]
+      unless headers.all? {|h| h.is_a? Array}
+        raise ArgumentError, ":headers (#{@headers.inspect}) must be an array of arrays"
+      end
+      true
+    end
 private
 
     def apply_format_to_row(row, format)
@@ -89,6 +101,11 @@ def create_format(name)
       Spreadsheet::Format.new @options[name] if @options.has_key? name
     end
 
+    def fill_headers(sheet, headers, row_index)
+      apply_format_to_row(sheet.row(row_index), @header_format)
+      fill_row(sheet.row(row_index), headers)
+    end
+
     def fill_row(row, column, model=nil)
       case column
       when String, Symbol

spec/writer_spec.rb

@@ -77,6 +77,31 @@
       )
     end
 
+    it "uses multiple header rows if the option is set and headers is an array of arrays" do
+      xls = make_book( mock_users,
+        :columns => [:name, :email, :age],
+        :multiple_header_rows => true,
+        :headers => [['Info', '', 'Other Info'], ['Nombre', 'Correo', 'Edad']]
+      )
+      check_sheet( xls.worksheets.first,
+        [ ['Info',   '',      'Other Info'],
+          ['Nombre', 'Correo',      'Edad'],
+          ['Peter',  'peter@gmail.com', 20],
+          ['John',   'john@gmail.com',  25],
+          ['Day9',   'day9@day9tv.com', 27]
+        ]
+      )
+    end
+
+    it "throws an error if multiple header rows option is set but headers is not an array of arrays" do
+      lambda {
+        make_book( mock_users,
+          :columns => [:name, :email, :age],
+          :multiple_header_rows => true,
+          :headers => [['Info', '', 'Other Info'], 'Nombre', 'Correo', 'Edad']
+      ) }.should raise_error
+    end
+
     it "includes no headers if the headers option is false" do
       xls = make_book( mock_users,
         :columns => [:name, :email, :age],

to_xls.gemspec

@@ -20,8 +20,7 @@ Gem::Specification.new do |s|
   s.require_paths = ["lib"]
 
   s.add_runtime_dependency "spreadsheet"
-  s.add_development_dependency "spreadsheet"
-  s.add_development_dependency "rspec", "~> 2.3.0"
+  s.add_development_dependency "rspec", "~> 2.4.0"
   s.add_development_dependency "bundler", "> 1.1.0"
   s.add_development_dependency "rake", "~> 0.9.2"
 end