5 files changed, 22 insertions, 4 deletions

diff --git a/examples/example.rb b/examples/example.rb
index 04ad6f4c..d93f5dcc 100644
--- a/examples/example.rb
+++ b/examples/example.rb
@@ -266,7 +266,8 @@ end
 
 wb.add_worksheet(:name => "custom column widths") do |sheet|
   sheet.add_row ["I use autowidth and am very wide", "I use a custom width and am narrow"]
-  sheet.column_widths nil, 3
+  sheet.add_row ['abcdefg', 'This is a very long text and should flow into the right cell', nil, 'xxx' ]
+  sheet.column_widths nil, 3, 5, nil
 end
 
 ##Fit to page printing
diff --git a/lib/axlsx/workbook/shared_strings_table.rb b/lib/axlsx/workbook/shared_strings_table.rb
index d9a22432..45402f5b 100644
--- a/lib/axlsx/workbook/shared_strings_table.rb
+++ b/lib/axlsx/workbook/shared_strings_table.rb
@@ -29,7 +29,7 @@ module Axlsx
     # Creates a new Shared Strings Table agains an array of cells
     # @param [Array] cells This is an array of all of the cells in the workbook
     def initialize(cells)
-      cells = cells.flatten.reject { |c| c.type != :string || c.value.start_with?('=') }
+      cells = cells.flatten.reject { |c| c.type != :string || c.value.nil? || c.value.start_with?('=') }
       @count = cells.size
       @unique_cells = []
       @shared_xml_string = ""
diff --git a/lib/axlsx/workbook/worksheet/cell.rb b/lib/axlsx/workbook/worksheet/cell.rb
index 3557a89b..f4c6ff09 100644
--- a/lib/axlsx/workbook/worksheet/cell.rb
+++ b/lib/axlsx/workbook/worksheet/cell.rb
@@ -307,12 +307,13 @@ module Axlsx
     # @param [String] str The string index the cell content will be appended to. Defaults to empty string.
     # @return [String] xml text for the cell
     def to_xml_string(r_index, c_index, str = '')
+      return str if @value.nil?
       str << '<c r="' << Axlsx::cell_r(c_index, r_index) << '" s="' << @style.to_s << '" '
       case @type
       when :string
         #parse formula
         if @value.start_with?('=')
-          str  << 't="str"><f>' << value.to_s.gsub('=', '') << '</f>'
+          str  << 't="str"><f>' << @value.to_s.gsub('=', '') << '</f>'
         else
           #parse shared
           if @ssti
@@ -382,6 +383,7 @@ module Axlsx
     #   About Time - Time in OOXML is *different* from what you might expect. The history as to why is interesting,  but you can safely assume that if you are generating docs on a mac, you will want to specify Workbook.1904 as true when using time typed values.
     # @see Axlsx#date1904
     def cast_value(v)
+      return nil if v.nil?
       if @type == :date
         self.style = STYLE_DATE if self.style == 0
         v
diff --git a/test/workbook/worksheet/tc_cell.rb b/test/workbook/worksheet/tc_cell.rb
index 2313a8ba..1cfd6169 100644
--- a/test/workbook/worksheet/tc_cell.rb
+++ b/test/workbook/worksheet/tc_cell.rb
@@ -98,7 +98,9 @@ class TestCell < Test::Unit::TestCase
     @c.type = :float
     assert_equal(@c.send(:cast_value, "1.0"), 1.0)
     @c.type = :string
-    assert_equal(@c.send(:cast_value, nil), "")
+    assert_equal(@c.send(:cast_value, nil), nil)
+    @c.type = :float
+    assert_equal(@c.send(:cast_value, nil), nil)
     @c.type = :boolean
     assert_equal(@c.send(:cast_value, true), 1)
     assert_equal(@c.send(:cast_value, false), 0)
diff --git a/test/workbook/worksheet/tc_row.rb b/test/workbook/worksheet/tc_row.rb
index d1507aa1..a953566e 100644
--- a/test/workbook/worksheet/tc_row.rb
+++ b/test/workbook/worksheet/tc_row.rb
@@ -27,6 +27,19 @@ class TestRow < Test::Unit::TestCase
     r.cells.each { |c| assert_equal(c.style,1) }
   end
 
+  def test_nil_cells
+    row = @ws.add_row([nil,1,2,nil,4,5,nil])
+    r_s_xml = Nokogiri::XML(row.to_xml_string(0, ''))
+    assert_equal(r_s_xml.xpath(".//row/c").size, 4)
+  end
+  
+  def test_nil_cell_r
+    row = @ws.add_row([nil,1,2,nil,4,5,nil])
+    r_s_xml = Nokogiri::XML(row.to_xml_string(0, ''))
+    assert_equal(r_s_xml.xpath(".//row/c").first['r'], 'B1')
+    assert_equal(r_s_xml.xpath(".//row/c").last['r'], 'F1')
+  end
+
   def test_index
     assert_equal(@row.index, @row.worksheet.rows.index(@row))
   end