[write] table column names have to be characters

src/helper_functions.cpp

@@ -477,6 +477,8 @@ void wide_to_long(
 
   auto startcol = start_col;
 
+  int32_t in_string_nums = string_nums;
+
   // pointer magic. even though these are extracted, they just point to the
   // memory in the data frame
   Rcpp::CharacterVector zz_row_r = Rcpp::as<Rcpp::CharacterVector>(zz["row_r"]);
@@ -514,7 +516,7 @@ void wide_to_long(
 
       int8_t vtyp = (int8_t)vtyps[i];
       // if colname is provided, the first row is always a character
-      if (ColNames & (j == 0)) vtyp = character;
+      if (ColNames && j == 0) vtyp = character;
       std::string vals = Rcpp::as<std::string>(cvec[j]);
       std::string row = std::to_string(startrow);
 
@@ -524,8 +526,13 @@ void wide_to_long(
       if (ref_str.compare("0") == 0)
       ref_str = col + row;
 
-      // factors can be numeric or string or both
-      if (vtyp == factor) string_nums = true;
+      // factors can be numeric or string or both. tables require the
+      // column name to be character and once we have overwritten for
+      // a factor, we have to reset string_nums.
+      if (!(ColNames && j == 0) && vtyp == factor)
+        string_nums = 1;
+      else
+        string_nums = in_string_nums;
 
       // create struct
       celltyp cell;

tests/testthat/test-tables.R

@@ -203,3 +203,23 @@ test_that("updating table works", {
   expect_equal(got, "A1:J4")
 
 })
+
+test_that("writing table headers with factor variables works", {
+  df <- data.frame(
+    fct = structure(
+      1:2,
+      levels = c(
+        "one",
+        "two"
+      ),
+      class = "factor"),
+    `1` = 1:2,
+    check.names = FALSE
+  )
+
+  wb <- wb_workbook()$add_worksheet()$add_data_table(x = df)
+
+  exp <- "<is><t>1</t></is>"
+  got <- wb$worksheets[[1]]$sheet_data$cc$is[[2]]
+  expect_equal(exp, got)
+})