From b60518d748f2d7df41fcc374c5f29bd308d8089a Mon Sep 17 00:00:00 2001
From: Zevero <zevero@users.noreply.github.com>
Date: Tue, 24 May 2016 08:36:40 +0200
Subject: [PATCH] Guarantee column order of objects. With headers.

---
 lib/csv-express.js | 52 +++++++++++++++-------------------------------
 1 file changed, 17 insertions(+), 35 deletions(-)

diff --git a/lib/csv-express.js b/lib/csv-express.js
index 9acd35f..872071e 100644
--- a/lib/csv-express.js
+++ b/lib/csv-express.js
@@ -26,7 +26,7 @@ exports.ignoreNullOrUndefined = true;
  */
 
 function escape(field) {
-  if (exports.ignoreNullOrUndefined && field == undefined) {
+  if (exports.ignoreNullOrUndefined && field === undefined) {
     return '';
   }
   if (exports.preventCast) {
@@ -38,27 +38,6 @@ function escape(field) {
   return '"' + String(field).replace(/\"/g, '""') + '"';
 }
 
-/**
- * Convert an object to an array of property values.
- *
- * Example:
- *    objToArray({ name: "john", id: 1 })
- *    // => [ "john", 1 ]
- *
- * @param {Object} obj The object to convert.
- * @return {Array} The array of object properties.
- * @api private
- */
-
-function objToArray(obj) {
-  var result = [];
-  for (var prop in obj) {
-    if (obj.hasOwnProperty(prop)) {
-      result.push(obj[prop]);
-    }
-  }
-  return result;
-}
 
 
  /*
@@ -75,23 +54,26 @@ res.csv = function(data, csvHeaders, headers, status) {
 
   this.charset = this.charset || 'utf-8';
   this.header('Content-Type', 'text/csv');
-
-  if (csvHeaders) {
-    var header = [];
-    for (var prop in data[0]) {
-      if (data[0].hasOwnProperty(prop)) {
-        header.push(prop);
-      }
-    }
-    body += header + '\r\n';
-  }
+  
+  var csvHeader_arr = [], csvHeader_pos = {}; //twice for better access of position
 
   data.forEach(function(item) {
-    if (!(item instanceof Array)) {
-      item = objToArray(item);
+    var arr = [];
+    if (item instanceof Array) arr = item;
+    else 
+    for (var prop in item) { //former objToArray but with correct header_csv position
+      if (item.hasOwnProperty(prop)) {
+        if (csvHeader_pos[prop] === undefined) {
+          csvHeader_pos[prop] = csvHeader_arr.length; 
+          csvHeader_arr.push(prop);
+        }
+        arr[csvHeader_pos[prop]] = item[prop];
+      }
     }
-    body += item.map(escape).join(exports.separator) + '\r\n';
+    body += arr.map(escape).join(exports.separator) + '\r\n';
   });
+  
+  if (csvHeaders && csvHeader_arr.length) body = csvHeader_arr.map(escape).join(exports.separator) + '\r\n' + body;
 
   if (this.charset !== 'utf-8') {
     body = iconv.encode(body, this.charset);