Pivot table generation fails when no Columns and multiple Data are provided. (#708)

fix to create pivot table in case there is no input from Columns
Co-authored-by: NJin Kim <jinhyuk.kim@cerence.com>
Co-authored-by: xuri <xuri.me@gmail.com>

pivotTable.go

@@ -460,6 +460,15 @@ func inPivotTableField(a []PivotTableField, x string) int {
 // definition and option.
 func (f *File) addPivotColFields(pt *xlsxPivotTableDefinition, opt *PivotTableOption) error {
 	if len(opt.Columns) == 0 {
+		if len(opt.Data) <= 1 {
+			return nil
+		}
+		pt.ColFields = &xlsxColFields{}
+		// in order to create pivot table in case there is no input from Columns
+		pt.ColFields.Count = 1
+		pt.ColFields.Field = append(pt.ColFields.Field, &xlsxField{
+			X: -2,
+		})
 		return nil
 	}
 

pivotTable_test.go

@@ -84,7 +84,7 @@ func TestAddPivotTable(t *testing.T) {
 		DataRange:       "Sheet1!$A$1:$E$31",
 		PivotTableRange: "Sheet1!$AE$2:$AG$33",
 		Rows:            []PivotTableField{{Data: "Month", DefaultSubtotal: true}, {Data: "Year"}},
-		Data:            []PivotTableField{{Data: "Sales", Subtotal: "Max", Name: "Summarize by Max"}},
+		Data:            []PivotTableField{{Data: "Sales", Subtotal: "Max", Name: "Summarize by Max"}, {Data: "Sales", Subtotal: "Average", Name: "Average of Sales"}},
 		RowGrandTotals:  true,
 		ColGrandTotals:  true,
 		ShowDrill:       true,
@@ -98,7 +98,7 @@ func TestAddPivotTable(t *testing.T) {
 		PivotTableRange:     "Sheet1!$AJ$2:$AP1$35",
 		Rows:                []PivotTableField{{Data: "Month", DefaultSubtotal: true}, {Data: "Year"}},
 		Filter:              []PivotTableField{{Data: "Region"}},
-		Columns:             []PivotTableField{{Data: "Type", DefaultSubtotal: true}},
+		Columns:             []PivotTableField{},
 		Data:                []PivotTableField{{Subtotal: "Sum", Name: "Summarize by Sum"}},
 		RowGrandTotals:      true,
 		ColGrandTotals:      true,