From 0dd6e27d8f8b4c7963698e5dc8f2864887a54d0a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Przemys=C5=82aw=20Szustak?= <przemyslaw.szustak@gmail.com>
Date: Mon, 15 Apr 2019 21:32:22 +0200
Subject: [PATCH] Conditional formatting - support for
 Conditional::CONDITION_CONTAINSBLANKS (#883)

Condition formating option was not supported. I unziped xlsx and found this formula to option blank field
---
 src/PhpSpreadsheet/Writer/Xlsx/Worksheet.php | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/PhpSpreadsheet/Writer/Xlsx/Worksheet.php b/src/PhpSpreadsheet/Writer/Xlsx/Worksheet.php
index 9600b1d0..7f48a6c1 100644
--- a/src/PhpSpreadsheet/Writer/Xlsx/Worksheet.php
+++ b/src/PhpSpreadsheet/Writer/Xlsx/Worksheet.php
@@ -519,6 +519,9 @@ class Worksheet extends WriterPart
                             // Formula
                             $objWriter->writeElement('formula', $formula);
                         }
+                    } elseif ($conditional->getConditionType() == Conditional::CONDITION_CONTAINSBLANKS) {
+                        // formula copied from ms xlsx xml source file
+                        $objWriter->writeElement('formula', 'LEN(TRIM(' . $cellCoordinate . '))=0');
                     }
 
                     $objWriter->endElement();