Simplifying exportWorkbook()

saveBlob() replaces complexity of processAndSave()

Author: ddooley

lib/utils/files.js

@@ -1,4 +1,4 @@
-import { utils as XlsxUtils, writeFile } from 'xlsx/xlsx.js';
+import { utils as XlsxUtils, writeFile} from 'xlsx/xlsx.js';
 import { saveAs } from 'file-saver';
 
 /**
@@ -120,6 +120,7 @@ export function createWorkbookFromJSON(jsonData) {
   return workbook;
 }
 
+/*
 function writeWorkbook(workbook, baseName, ext, opt = {}) {
   if (ext === 'xlsx' || ext === 'xls') {
     // can support multiple sheets in one file
@@ -144,6 +145,7 @@ function writeWorkbook(workbook, baseName, ext, opt = {}) {
     });
   }
 }
+*/
 
 /**
  * Download matrix to file.
@@ -158,111 +160,110 @@ function writeWorkbook(workbook, baseName, ext, opt = {}) {
  * @param {String} ext Extension of downloaded file.
  */
 export function exportWorkbook(workbook, baseName, ext) {
-  switch (ext) {
-    case 'xlsx':
-    case 'xls':
-      writeWorkbook(workbook, baseName, ext);
-      break;
-    case 'csv':
-      processAndSave(
-        workbook,
-        baseName,
-        'csv',
-        ',',
-        'text/plain;charset=UTF-8'
-      );
-      break;
-
-    case 'csv (UTF-16)':
-      processAndSave(
-        workbook,
-        baseName,
-        'csv',
-        ',',
-        'text/plain;charset=UTF-16LE'
-      );
-      break;
-
-    case 'tsv':
-      processAndSave(
-        workbook,
-        baseName,
-        'tsv',
-        '\t',
-        'text/plain;charset=UTF-8'
-      );
-      break;
-
-    case 'tsv (UTF-16)':
-      processAndSave(
-        workbook,
-        baseName,
-        'tsv',
-        '\t',
-        'text/plain;charset=UTF-16LE'
-      );
-      break;
-
-    case 'csv (UTF-8, no BOM)':
-      processAndSave(
-        workbook,
-        baseName,
-        'csv',
-        ',',
-        'text/plain;charset=UTF-8',
-        false
-      );
-      break;
-
-    case 'csv (ASCII)':
-      processAndSave(
-        workbook,
-        baseName,
-        'csv',
-        ',',
-        'text/plain;charset=us-ascii',
-        false
-      );
-      break;
-  }
-}
 
-function processAndSave(
-  workbook,
-  baseName,
-  ext,
-  delimiter,
-  mimeType,
-  includeBOM = true
-) {
+  // Often just one sheet, but if multiple, then each gets file name + _ + template (class) name
   const sheets = workbook.SheetNames;
   sheets.forEach((sheetName) => {
-    let data = '';
-
     const worksheet = workbook.Sheets[sheetName];
+    const fileName = `${baseName}${sheets.length > 1 ? `_${sheetName}` : ''}.${ext.split(' ')[0]}`;
+    var data = '';
+
+    switch (ext) {
+      case 'xlsx':
+      case 'xls':
+        // Note, mimeType always set to application/zip in these cases.
+        writeFile(workbook, `${baseName}.${ext}`); //, opt
+        break;
+
+      /* Notes: 
+       See 
+       - https://docs.sheetjs.com/docs/api/write-options/
+       - https://docs.sheetjs.com/docs/api/utilities/csv#csv-output
+       * We want more accurate mimeTypes, so saveBlob() allows this.
+       * writeFile(bookType: 'csv'...) output includes the UTF-8 byte order
+       * mark ("BOM").
+       * writeFile(bookType: 'tsv'...) output will NOT include the BOM ???
+       * sheet_to_csv() will return JavaScript strings without the UTF-8 BOM.
+       * sheet_to_txt(): If encoding support is available, the output will be
+       * encoded in CP1200 and the UTF-16 BOM will be added. If encoding 
+       * support is not available, the output will be encoded as a standard
+       * string. 
+       *    So is encoding support available?
+      */
+      case 'csv':
+        // writeFile(workbook, fileName, {bookType: 'csv', FS: ','});
+        data = XlsxUtils.sheet_to_csv(worksheet, {FS: ','});
+        data = '\uFEFF' + data; //BOM
+        saveBlob(data, fileName, 'text/plain;charset=UTF-8');
+        break;
+
+      case 'csv (UTF-16)':
+        //writeFile(workbook, fileName, {bookType: 'txt', FS: ','});
+        data = XlsxUtils.sheet_to_csv(worksheet, {FS: ','});
+        data = '\uFEFF' + data; //BOM
+        saveBlob(data, fileName, 'text/plain;charset=UTF-16LE');
+        break;
+
+      case 'tsv': // BOM version
+        //writeFile(workbook, fileName, {bookType: 'csv', FS: '\t'}); 
+        data = XlsxUtils.sheet_to_csv(worksheet, {FS: '\t'});
+        data = '\uFEFF' + data; //BOM
+        saveBlob(data, fileName, 'text/plain;charset=UTF-8');
+        break;
+
+      case 'tsv (UTF-16)':
+        data = XlsxUtils.sheet_to_txt(worksheet, {FS: '\t'});
+        saveBlob(data, fileName, 'text/plain;charset=UTF-16LE');
+        break;
+
+      case 'csv (UTF-8, no BOM)':
+        data = XlsxUtils.sheet_to_csv(worksheet, {FS: ','});
+        saveBlob(data, fileName, 'text/plain;charset=UTF-8');
+        break;
+
+      case 'csv (ASCII)': // no BOM
+        data = XlsxUtils.sheet_to_csv(worksheet, {FS: ','});
+        saveBlob(data, fileName, 'text/plain;charset=us-ascii');
+        break;
+    }
+  })
+};
+
+// Saves workbook which may have multiple sheets into one or more files.
+// ext:        csv, csv (UTF-16), tsv, tsv (UTF-16)
+// ext no BOM: csv (UTF-8, no BOM), csv (ASCII)
+// This script can enhance file type with mimeType - but is that something sheetJS can't do?
+function saveBlob(
+  data,
+  fileName,
+  mimeType
+) {
+ 
+    /*
     const sheetData = XlsxUtils.sheet_to_json(worksheet, { header: 1 });
 
     const formattedData = sheetData
       .map((row) => row.join(delimiter))
       .join('\n');
     data += formattedData + '\n';
 
+    // Insert BOM character.
     if (includeBOM && mimeType.includes('UTF-8')) {
       data = '\uFEFF' + data;
     }
+    */
 
+    // https://docs.sheetjs.com/docs/api/utilities/csv#csv-output
+    // "If encoding support is available, the output will be encoded in CP1200 and the UTF-16 BOM will be added. If encoding support is not available, the output will be encoded as a standard string.""
+
+    // Enhancing with mimeType
     const blob = new Blob([data], { type: mimeType });
-    saveAs(
-      blob,
-      `${baseName}${sheets.length > 1 ? `_${sheetName}` : ''}.${
-        ext.split(' ')[0]
-      }`
-    );
-  });
-}
+    saveAs(blob, fileName);
+};
 
 // TODO: refactor to export matrix
 export function exportFile(matrix, baseName, ext) {
+  console.log("running exportFile", matrix, baseName, ext)
   const worksheet = XlsxUtils.aoa_to_sheet(matrix);
   const workbook = XlsxUtils.book_new();
   XlsxUtils.book_append_sheet(workbook, worksheet, DEFAULT_SHEETNAME);