From 111567b74e05a091d01cd19bbe2fd9f01eef64d9 Mon Sep 17 00:00:00 2001
From: Todd <todd@baliance.com>
Date: Thu, 14 Sep 2017 17:16:19 -0500
Subject: [PATCH] spreadsheet: default new cells to numeric with implicit zero
 value

---
 spreadsheet/cell.go | 4 +++-
 spreadsheet/row.go  | 4 ++++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/spreadsheet/cell.go b/spreadsheet/cell.go
index 0729731b..74c8bed7 100644
--- a/spreadsheet/cell.go
+++ b/spreadsheet/cell.go
@@ -53,6 +53,7 @@ func (c Cell) clearValue() {
 	c.x.F = nil
 	c.x.Is = nil
 	c.x.V = nil
+	c.x.TAttr = sml.ST_CellTypeUnset
 }
 
 // SetInlineString adds a string inline instead of in the shared strings table.
@@ -113,7 +114,8 @@ func (c Cell) GetValueAsNumber() (float64, error) {
 		return math.NaN(), errors.New("cell is not of number type")
 	}
 	if c.x.V == nil {
-		return math.NaN(), errors.New("cell has no value")
+		// empty cells have an implicit zero value
+		return 0, nil
 	}
 	return strconv.ParseFloat(*c.x.V, 64)
 }
diff --git a/spreadsheet/row.go b/spreadsheet/row.go
index 2a8c681b..e8eedd2f 100644
--- a/spreadsheet/row.go
+++ b/spreadsheet/row.go
@@ -62,6 +62,8 @@ func (r Row) SetHidden(hidden bool) {
 // AddCell adds a cell to a spreadsheet.
 func (r Row) AddCell() Cell {
 	c := spreadsheetml.NewCT_Cell()
+	c.TAttr = spreadsheetml.ST_CellTypeN
+
 	r.x.C = append(r.x.C, c)
 	nextIdx := uint32(0)
 	for _, c := range r.x.C {
@@ -92,6 +94,8 @@ func (r Row) Cells() []Cell {
 // invaild spreadsheet.
 func (r Row) AddNamedCell(col string) Cell {
 	c := spreadsheetml.NewCT_Cell()
+	c.TAttr = spreadsheetml.ST_CellTypeN
+
 	r.x.C = append(r.x.C, c)
 	c.RAttr = gooxml.Stringf("%s%d", col, r.RowNumber())
 	return Cell{r.w, r.s, r.x, c}