Relax validation on merge cells to allow input of a single cell

Author: MarkBaker

src/PhpSpreadsheet/Worksheet/Worksheet.php

@@ -1752,31 +1752,35 @@ public function mergeCells($range)
     {
         $range = Functions::trimSheetFromCellReference(Validations::validateCellRange($range));
 
-        if (preg_match('/^([A-Z]+)(\\d+):([A-Z]+)(\\d+)$/', $range, $matches) === 1) {
-            $this->mergeCells[$range] = $range;
-            $firstRow = (int) $matches[2];
-            $lastRow = (int) $matches[4];
-            $firstColumn = $matches[1];
-            $lastColumn = $matches[3];
-            $firstColumnIndex = Coordinate::columnIndexFromString($firstColumn);
-            $lastColumnIndex = Coordinate::columnIndexFromString($lastColumn);
-            $numberRows = $lastRow - $firstRow;
-            $numberColumns = $lastColumnIndex - $firstColumnIndex;
-
-            // create upper left cell if it does not already exist
-            $upperLeft = "{$firstColumn}{$firstRow}";
-            if (!$this->cellExists($upperLeft)) {
-                $this->getCell($upperLeft)->setValueExplicit(null, DataType::TYPE_NULL);
-            }
+        if (strpos($range, ':') === false) {
+            $range .= ":{$range}";
+        }
 
-            // Blank out the rest of the cells in the range (if they exist)
-            if ($numberRows > $numberColumns) {
-                $this->clearMergeCellsByColumn($firstColumn, $lastColumn, $firstRow, $lastRow, $upperLeft);
-            } else {
-                $this->clearMergeCellsByRow($firstColumn, $lastColumnIndex, $firstRow, $lastRow, $upperLeft);
-            }
+        if (preg_match('/^([A-Z]+)(\\d+):([A-Z]+)(\\d+)$/', $range, $matches) !== 1) {
+            throw new Exception('Merge must be on a valid range of cells.');
+        }
+
+        $this->mergeCells[$range] = $range;
+        $firstRow = (int) $matches[2];
+        $lastRow = (int) $matches[4];
+        $firstColumn = $matches[1];
+        $lastColumn = $matches[3];
+        $firstColumnIndex = Coordinate::columnIndexFromString($firstColumn);
+        $lastColumnIndex = Coordinate::columnIndexFromString($lastColumn);
+        $numberRows = $lastRow - $firstRow;
+        $numberColumns = $lastColumnIndex - $firstColumnIndex;
+
+        // create upper left cell if it does not already exist
+        $upperLeft = "{$firstColumn}{$firstRow}";
+        if (!$this->cellExists($upperLeft)) {
+            $this->getCell($upperLeft)->setValueExplicit(null, DataType::TYPE_NULL);
+        }
+
+        // Blank out the rest of the cells in the range (if they exist)
+        if ($numberRows > $numberColumns) {
+            $this->clearMergeCellsByColumn($firstColumn, $lastColumn, $firstRow, $lastRow, $upperLeft);
         } else {
-            throw new Exception('Merge must be set on a range of cells.');
+            $this->clearMergeCellsByRow($firstColumn, $lastColumnIndex, $firstRow, $lastRow, $upperLeft);
         }
 
         return $this;

tests/PhpSpreadsheetTests/Calculation/MergedCellTest.php

@@ -100,7 +100,7 @@ private function setBadRange(Worksheet $sheet, string $range): void
             $sheet->mergeCells($range);
             self::fail("Expected invalid merge range $range");
         } catch (SpreadException $e) {
-            self::assertSame('Merge must be set on a range of cells.', $e->getMessage());
+            self::assertSame('Merge must be on a valid range of cells.', $e->getMessage());
         }
     }
 
@@ -109,7 +109,8 @@ public function testMergedBadRange(): void
         $spreadSheet = new Spreadsheet();
 
         $dataSheet = $spreadSheet->getActiveSheet();
-        $this->setBadRange($dataSheet, 'B1');
+        // TODO - Reinstate full validation and disallow single cell merging for version 2.0
+//        $this->setBadRange($dataSheet, 'B1');
         $this->setBadRange($dataSheet, 'Invalid');
         $this->setBadRange($dataSheet, '1');
         $this->setBadRange($dataSheet, 'C');