Mirrors the fix for issue 869 on the master branch (#873)

* Mirrors the fix for issue 869 on the master branch
* Fixing test and early return property set

---------

Co-authored-by: RiRiSharp <[email protected]>

Author: michelebastione

samples/xlsx/TestIssue869/DateTimeMidnight.xlsx

@@ -15,5 +15,28 @@ public abstract class Configuration : IConfiguration
         ///     When exporting using DataReader, the data not in DynamicColumn will be filtered.
         /// </summary>
         public bool DynamicColumnFirst { get; set; } = false;
+        
+        /// <summary>
+        /// Specifies when and how DateTime values are converted to DateOnly values.
+        /// </summary>
+        public DateOnlyConversionMode DateOnlyConversionMode { get; set; }
+    }
+    
+    public enum DateOnlyConversionMode
+    {
+        /// <summary>
+        /// No conversion is applied and DateOnly values are not transformed.
+        /// </summary>
+        None,
+
+        /// <summary>
+        /// Allows conversion from DateTime to DateOnly only if the time component is exactly midnight (00:00:00).
+        /// </summary>
+        RequireMidnight,
+
+        /// <summary>
+        /// Converts DateTime to DateOnly by ignoring the time part completely, assuming the time component is not critical.
+        /// </summary>
+        IgnoreTimePart
     }
 }

samples/xlsx/TestIssue869/DateTimeNotMidnight.xlsx

@@ -142,6 +142,16 @@ public static bool IsNumericType(Type type, bool isNullableUnderlyingType = fals
                     pInfo.Property.SetValue(v, newValue);
                     return newValue;
                 }
+                
+                if (itemValue is DateTime dateTimeValue && config.DateOnlyConversionMode != DateOnlyConversionMode.None)
+                {
+                    if (config.DateOnlyConversionMode == DateOnlyConversionMode.RequireMidnight && dateTimeValue.TimeOfDay != TimeSpan.Zero)
+                        throw new InvalidCastException($"Could not convert cell of type DateTime to DateOnly, because DateTime was not at midnight, but at {dateTimeValue:HH:mm:ss}.");
+
+                    newValue = DateOnly.FromDateTime(dateTimeValue);
+                    pInfo.Property.SetValue(v, newValue);
+                    return newValue;
+                }
 
                 var vs = itemValue?.ToString();
                 if (pInfo.ExcelFormat != null)

src/MiniExcel/IConfiguration.cs

@@ -4661,4 +4661,42 @@ public void TestIssue809()
         Assert.Equal(null, rows[0].A);
         Assert.Equal(2, rows[2].B);
     }
+    
+    
+    private class Issue869
+    {
+        public string? Name { get; set; }
+        public DateOnly? Date { get; set; }
+    }
+
+    [Theory]
+    [InlineData("DateTimeMidnight", DateOnlyConversionMode.None, true)]
+    [InlineData("DateTimeNotMidnight", DateOnlyConversionMode.None, true)]
+    [InlineData("DateTimeMidnight", DateOnlyConversionMode.RequireMidnight, false)]
+    [InlineData("DateTimeNotMidnight", DateOnlyConversionMode.RequireMidnight, true)]
+    [InlineData("DateTimeMidnight", DateOnlyConversionMode.IgnoreTimePart, false)]
+    [InlineData("DateTimeNotMidnight", DateOnlyConversionMode.IgnoreTimePart, false)]
+    public void TestIssue869(string fileName, DateOnlyConversionMode mode, bool throwsException)
+    {
+        var path = PathHelper.GetFile($"xlsx/TestIssue869/{fileName}.xlsx");
+        var config = new OpenXmlConfiguration { DateOnlyConversionMode = mode };
+
+        var testFn = () => MiniExcel.Query<Issue869>(path, configuration: config).ToList();
+        if (throwsException)
+        {
+            Assert.Throws<ExcelInvalidCastException>(testFn);
+        }
+        else
+        {
+            try
+            {
+                var result = testFn();
+                Assert.Equal(new DateOnly(2025, 1, 1), result[0].Date);
+            }
+            catch (Exception ex)
+            {
+                Assert.Fail($"No exception should be thrown, but one was still thrown: {ex}.");
+            }
+        }
+    }
 }