Add DateOnlyCellValue and TimeOnlyCellValue

main/HSSF/UserModel/HSSFCell.cs

@@ -850,44 +850,53 @@ private void CheckFormulaCachedValueType(CellType expectedTypeCode, FormulaRecor
 
         /// <summary>
         /// Get the value of the cell as a date.  For strings we throw an exception.
-        /// For blank cells we return a null.
+        /// For non-Numeric cells including blank cell we return a null.
         /// </summary>
         /// <value>The date cell value.</value>
-        public DateTime DateCellValue
+        public DateTime? DateCellValue
         {
             get
             {
-                if (cellType == CellType.Blank)
+                if (CellType != CellType.Numeric && CellType != CellType.Formula)
                 {
-                    return DateTime.MaxValue;
+                    return null;
                 }
-                if (cellType == CellType.String)
-                {
-                    throw new InvalidDataException(
-                        "You cannot get a date value from a String based cell");
-                }
-                if (cellType == CellType.Boolean)
-                {
-                    throw new InvalidDataException(
-                        "You cannot get a date value from a bool cell");
-                }
-                if (cellType == CellType.Error)
+                double value = this.NumericCellValue;
+                return DateUtil.GetJavaDate(value, book.IsDate1904());
+            }
+        }
+#if NET6_0_OR_GREATER
+        public DateOnly? DateOnlyCellValue 
+        { 
+            get{
+                if (CellType != CellType.Numeric && CellType != CellType.Formula)
                 {
-                    throw new InvalidDataException(
-                        "You cannot get a date value from an error cell");
+                    return null;
                 }
                 double value = this.NumericCellValue;
                 if (book.IsDate1904())
                 {
-                    return DateUtil.GetJavaDate(value, true);
+                    return DateOnly.FromDateTime(DateUtil.GetJavaDate(value, true));
                 }
                 else
                 {
-                    return DateUtil.GetJavaDate(value, false);
+                    return DateOnly.FromDateTime(DateUtil.GetJavaDate(value, false));
+                }
+            } 
+        }
+        public TimeOnly? TimeOnlyCellValue 
+        { 
+            get{
+                if (CellType != CellType.Numeric && CellType != CellType.Formula)
+                {
+                    return null;
                 }
+                double value = NumericCellValue;
+                bool date1904 = Sheet.Workbook.IsDate1904();
+                return TimeOnly.FromDateTime(DateUtil.GetJavaDate(value, date1904));
             }
         }
-
+#endif
         /// <summary>
         /// Get the value of the cell as a string - for numeric cells we throw an exception.
         /// For blank cells we return an empty string.

main/SS/Format/CellFormat.cs

@@ -292,7 +292,7 @@ public CellFormatResult Apply(ICell c)
                     {
                         if (DateUtil.IsValidExcelDate(value))
                         {
-                            return Apply(c.DateCellValue, value);
+                            return Apply((DateTime)c.DateCellValue, value);
                         }
                         else
                         {

main/SS/UserModel/Cell.cs

@@ -190,12 +190,21 @@ CellType CellType
         double NumericCellValue { get; }
 
         /// <summary>
-        /// Get the value of the cell as a date.
+        /// Get the value of the cell as a date. For non-Numeric cells including blank cell we return a null.
         /// </summary>
         /// <exception cref="InvalidOperationException">if the cell type returned by GetCellType() is CELL_TYPE_STRING</exception>
         /// <exception cref="FormatException">if the cell value isn't a parsable double</exception>
-        DateTime DateCellValue { get; }
-
+        DateTime? DateCellValue { get; }
+#if NET6_0_OR_GREATER
+        /// <summary>
+        /// Get DateOnly-type cell value
+        /// </summary>
+        DateOnly? DateOnlyCellValue { get; }
+        /// <summary>
+        /// Get TimeOnly-type cell value
+        /// </summary>
+        TimeOnly? TimeOnlyCellValue { get; }
+#endif
         /// <summary>
         /// Get the value of the cell RichTextString
         /// </summary>

main/SS/UserModel/DataFormatter.cs

@@ -842,8 +842,10 @@ private String GetFormattedDateString(ICell cell)
                       cell.NumericCellValue
                 );
             }
-            DateTime d = cell.DateCellValue;
-            return PerformDateFormatting(d, dateFormat);
+            var d = cell.DateCellValue;
+            if (d == null)
+                return "";
+            return PerformDateFormatting((DateTime)d, dateFormat);
         }
 
         /**

ooxml/XSSF/Streaming/SXSSFCell.cs

@@ -15,6 +15,7 @@ the License.  You may obtain a copy of the License at
    limitations under the License.
 ==================================================================== */
 using System;
+using System.IO;
 using NPOI.SS;
 using NPOI.SS.Formula.Eval;
 using NPOI.SS.UserModel;
@@ -196,23 +197,51 @@ public int ColumnIndex
                 return _row.GetCellIndex(this);
             }
         }
-
-        public DateTime DateCellValue
+        /// <summary>
+        /// Get DateTime-type cell value
+        /// </summary>
+        public DateTime? DateCellValue
         {
             get
             {
-                CellType cellType = _value.GetType();
-                if (cellType == CellType.Blank)
+                if (CellType != CellType.Numeric && CellType != CellType.Formula)
                 {
-                    return new DateTime();
+                    return null;
                 }
-
                 double value = NumericCellValue;
                 bool date1904 = Sheet.Workbook.IsDate1904();
-                return DateUtil.GetJavaDate(value, date1904);
+                return DateUtil.GetJavaDate(value,date1904);
             }
         }
-
+#if NET6_0_OR_GREATER
+        /// <summary>
+        /// Get DateOnly-type cell value
+        /// </summary>
+        public DateOnly? DateOnlyCellValue 
+        { 
+            get{
+                if (CellType != CellType.Numeric && CellType != CellType.Formula)
+                {
+                    return null;
+                }
+                double value = NumericCellValue;
+                bool date1904 = Sheet.Workbook.IsDate1904();
+                return DateOnly.FromDateTime(DateUtil.GetJavaDate(value, date1904));
+            }
+        }
+        public TimeOnly? TimeOnlyCellValue 
+        { 
+            get{
+                if (CellType != CellType.Numeric && CellType != CellType.Formula)
+                {
+                    return null;
+                }
+                double value = NumericCellValue;
+                bool date1904 = Sheet.Workbook.IsDate1904();
+                return TimeOnly.FromDateTime(DateUtil.GetJavaDate(value, date1904));
+            }
+        }
+#endif
         public byte ErrorCellValue
         {
             get

ooxml/XSSF/UserModel/XSSFCell.cs

@@ -26,6 +26,8 @@ limitations under the License.
 using NPOI.Util;
 using NPOI.SS.Formula.Eval;
 using System.Globalization;
+using System.IO;
+
 namespace NPOI.XSSF.UserModel
 {
 
@@ -827,20 +829,47 @@ private CellType GetBaseCellType(bool blankCells)
         /// <summary>
         /// Get the value of the cell as a date.
         /// </summary>
-        public DateTime DateCellValue
+        public DateTime? DateCellValue
         {
             get
             {
-                if (CellType == CellType.Blank)
+                if (CellType != CellType.Numeric && CellType != CellType.Formula)
                 {
-                    return DateTime.MinValue;
+                    return null;
                 }
 
                 double value = NumericCellValue;
                 bool date1904 = Sheet.Workbook.IsDate1904();
                 return DateUtil.GetJavaDate(value, date1904);
             }
         }
+#if NET6_0_OR_GREATER
+        public DateOnly? DateOnlyCellValue 
+        { 
+            get{
+                if (CellType != CellType.Numeric && CellType != CellType.Formula)
+                {
+                    return null;
+                }
+                double value = NumericCellValue;
+                bool date1904 = Sheet.Workbook.IsDate1904();
+                return DateOnly.FromDateTime(DateUtil.GetJavaDate(value, date1904));
+            }
+        }
+
+        public TimeOnly? TimeOnlyCellValue 
+        { 
+            get{
+                if (CellType != CellType.Numeric && CellType != CellType.Formula)
+                {
+                    return null;
+                }
+                double value = NumericCellValue;
+                bool date1904 = Sheet.Workbook.IsDate1904();
+                return TimeOnly.FromDateTime(DateUtil.GetJavaDate(value, date1904));
+            }
+        }
+#endif
         public void SetCellValue(DateTime? value)
         {
             if (value == null)

testcases/main/HSSF/UserModel/TestHSSFCell.cs

@@ -186,7 +186,7 @@ private static void SetCell(HSSFWorkbook workbook, int rowIdx, int colIdx, DateT
             cell.SetCellValue(date);
         }
 
-        private static DateTime ReadCell(HSSFWorkbook workbook, int rowIdx, int colIdx)
+        private static DateTime? ReadCell(HSSFWorkbook workbook, int rowIdx, int colIdx)
         {
             NPOI.SS.UserModel.ISheet sheet = workbook.GetSheetAt(0);
             IRow row = sheet.GetRow(rowIdx);
@@ -485,7 +485,7 @@ public void TestCellType()
             HSSFCell cell = row.CreateCell(0) as HSSFCell;
 
             cell.SetCellType(CellType.Blank);
-            Assert.AreEqual("9999-12-31 23:59:59.999", cell.DateCellValue.ToString("yyyy-MM-dd HH:mm:ss.fff"));
+            Assert.IsNull(cell.DateCellValue);
             Assert.IsFalse(cell.BooleanCellValue);
             Assert.AreEqual("", cell.ToString());
 
@@ -520,6 +520,25 @@ public void TestCellType()
             cell.SetCellValue((IRichTextString)null);
             wb.Close();
         }
+
+        [Test]
+        public void TestGetDateTimeCellValue()
+        {
+            HSSFWorkbook wb = new HSSFWorkbook();
+            HSSFSheet sheet = wb.CreateSheet() as HSSFSheet;
+            HSSFRow row = sheet.CreateRow(0) as HSSFRow;
+            HSSFCell cell = row.CreateCell(0) as HSSFCell;
+            cell.SetCellValue(new DateTime(2022, 5, 10, 13, 20, 50));
+            Assert.IsNotNull(cell.DateCellValue);
+            Assert.AreEqual(new DateTime(2022, 5, 10, 13, 20, 50), cell.DateCellValue);
+#if NET6_0_OR_GREATER
+            Assert.AreEqual(new DateOnly(2022, 5, 10), cell.DateOnlyCellValue);
+            Assert.AreEqual(new TimeOnly(13, 20, 50), cell.TimeOnlyCellValue);
+#endif
+            HSSFCell cell2 = row.CreateCell(1) as HSSFCell;
+            cell2.SetCellValue("test");
+            Assert.IsNull(cell2.DateCellValue);
+        }
     }
 
 }

testcases/main/HSSF/UserModel/TestHSSFDateUtil.cs

@@ -549,7 +549,7 @@ public void TestBug19172()
 
             cell.SetCellValue(valueToTest);
 
-            DateTime returnedValue = cell.DateCellValue;
+            DateTime returnedValue = (DateTime)cell.DateCellValue;
 
             Assert.AreEqual(valueToTest.TimeOfDay, returnedValue.TimeOfDay);
         }

testcases/main/SS/UserModel/BaseTestCell.cs

@@ -84,13 +84,13 @@ public void TestSetValues()
 
             DateTime dt = DateTime.Now.AddMilliseconds(123456789);
             cell.SetCellValue(dt);
-            Assert.IsTrue((dt.Ticks - cell.DateCellValue.Ticks) >= -20000);
+            Assert.IsTrue((dt.Ticks - ((DateTime)cell.DateCellValue).Ticks) >= -20000);
             Assert.AreEqual(CellType.Numeric, cell.CellType);
             AssertProhibitedValueAccess(cell, CellType.Boolean, CellType.String,
                     CellType.Formula, CellType.Error);
 
             cell.SetCellValue(dt);
-            Assert.IsTrue((dt.Ticks - cell.DateCellValue.Ticks) >= -20000);
+            Assert.IsTrue((dt.Ticks - ((DateTime)cell.DateCellValue).Ticks) >= -20000);
             Assert.AreEqual(CellType.Numeric, cell.CellType);
             AssertProhibitedValueAccess(cell, CellType.Boolean, CellType.String,
                     CellType.Formula, CellType.Error);

testcases/ooxml/XSSF/UserModel/TestXSSFWorkbook.cs

@@ -1053,7 +1053,7 @@ public void TestBug56957CloseWorkbook()
 
                 // read-only mode works!
                 workbook = WorkbookFactory.Create(OPCPackage.Open(file, PackageAccess.READ));
-                DateTime dateAct = workbook.GetSheetAt(0).GetRow(0).GetCell(0, MissingCellPolicy.CREATE_NULL_AS_BLANK).DateCellValue;
+                var dateAct = workbook.GetSheetAt(0).GetRow(0).GetCell(0, MissingCellPolicy.CREATE_NULL_AS_BLANK).DateCellValue;
                 Assert.AreEqual(dateExp, dateAct);
                 workbook.Close();
                 workbook = null;