fix: clear table placeholders when data is empty (#344)

Author: smakaiberriesandco

ClosedXML.Report/RangeInterpreter.cs

@@ -187,7 +187,10 @@ string EvalString(string str)
                         {
                             var rangeWithoutOptionsRow = growedRange.Worksheet
                                 .Range(growedRange.FirstCell(), growedRange.LastCell().CellAbove());
-                            rangeWithoutOptionsRow.Delete(XLShiftDeletedCells.ShiftCellsUp);
+                            if (growedRange.Worksheet.Tables.Any(t => t.Contains(rangeWithoutOptionsRow)))
+                                growedRange.Clear();
+                            else
+                                rangeWithoutOptionsRow.Delete(XLShiftDeletedCells.ShiftCellsUp);
                         }
                         continue;
                     }

tests/ClosedXML.Report.Tests/RangeInterpreterTests.cs

@@ -1,6 +1,7 @@
 using ClosedXML.Excel;
 using FluentAssertions;
 using System.Collections.Generic;
+using System.Data;
 using System.Linq;
 using Xunit;
 using Xunit.Abstractions;
@@ -104,6 +105,42 @@ public void ShouldNotThrowExceptionIfAccessSomeChildrenNullProp()
             ws.Cell("B4").GetString().Should().Be("Material 1");
         }
 
+        [Fact]
+        public void ShouldClearPlaceHolders()
+        {
+            var wbTemplate = new XLWorkbook();
+            var ws = wbTemplate.AddWorksheet();
+            var template = new XLTemplate(wbTemplate);
+
+            ws.Cell("B8").InsertTable(new DataTable()
+            {
+                Columns =
+                {
+                    "Id",
+                    "Name"
+                },
+                Rows =
+                {
+                    { "{{item.Id}}", "{{item.Name}}" }
+                }
+            });
+            ws.Range("B9:C9").AddToNamed("TestRange");
+
+            var model = new
+            {
+                TestRange = new List<Item>()
+            };
+
+            template.AddVariable(model);
+
+            template.Generate();
+
+            ws.Cell("B8").GetString().Should().Be("Id");
+            ws.Cell("C8").GetString().Should().Be("Name");
+            ws.Cell("B9").GetString().Should().BeEmpty();
+            ws.Cell("C9").GetString().Should().BeEmpty();
+        }
+
         [Fact]
         public void ShouldDestroyEmptyTable()
         {