Use DataFormat when reading (fixes #306)

Author: mganss

ExcelMapper.Tests/Tests.cs

@@ -3197,7 +3197,7 @@ record Stato
         [Test]
         public void StatoTest()
         {
-            var excel = new ExcelMapper {  CreateMissingHeaders = true, HeaderRow = true };
+            var excel = new ExcelMapper { CreateMissingHeaders = true, HeaderRow = true };
 
             var statos = new Stato[]
             {
@@ -3210,5 +3210,22 @@ public void StatoTest()
 
             AssertEquivalent(statos, statos2);
         }
+
+        record IdNumber
+        {
+            [DataFormat(1)]
+            public string IdNo { get; set; }
+        }
+
+        [Test]
+        public void FormatTest()
+        {
+            var rows = new ExcelMapper(@"../../../xlsx/Format.xlsx").Fetch<IdNumber>().ToList();
+            AssertEquivalent(rows, new[]
+            {
+                new IdNumber { IdNo = "8005065137086" },
+                new IdNumber { IdNo = "8402155792088" }
+            });
+        }
     }
 }

ExcelMapper.Tests/xlsx/Format.xlsx

@@ -1495,7 +1495,18 @@ object GetCellValue(ICell cell, ColumnInfo targetColumn)
                 case CellType.Numeric:
                     if (!formulaResult && targetColumn.PropertyType == typeof(string))
                     {
-                        return DataFormatter.FormatCellValue(cell);
+                        if (targetColumn.BuiltinFormat != 0 || targetColumn.CustomFormat != null)
+                        {
+                            var formatIndex = targetColumn.BuiltinFormat != 0 ? targetColumn.BuiltinFormat : cell.CellStyle.DataFormat;
+                            var formatString = targetColumn.BuiltinFormat != 0 ? BuiltinFormats.GetBuiltinFormat(targetColumn.BuiltinFormat)
+                                : targetColumn.CustomFormat ?? cell.CellStyle.GetDataFormatString();
+                            var formattedValue = DataFormatter.FormatRawCellContents(cell.NumericCellValue, formatIndex, formatString);
+                            return formattedValue;
+                        }
+                        else
+                        {
+                            return DataFormatter.FormatCellValue(cell);
+                        }
                     }
                     else if (cell.NumericCellValue <= maxDate && DateUtil.IsCellDateFormatted(cell))
                     {