feat: add escapeHeaderNestedDots option to allow for unescaping generated header keys

Fixes #245

Author: mrodrig

src/constants.ts

@@ -25,6 +25,7 @@ export const defaultJson2CsvOptions: DefaultJson2CsvOptions = {
         eol   : '\n'
     },
     emptyFieldValue: undefined,
+    escapeHeaderNestedDots: true,
     excelBOM: false,
     excludeKeys: [],
     expandNestedObjects: true,

src/json2csv.ts

@@ -15,7 +15,7 @@ export const Json2Csv = function(options: FullJson2CsvOptions) {
             expandNestedObjects: options.expandNestedObjects,
             expandArrayObjects: expandingWithoutUnwinding,
             ignoreEmptyArraysWhenExpanding: expandingWithoutUnwinding,
-            escapeNestedDots: true
+            escapeNestedDots: true,
         };
 
     /** HEADER FIELD FUNCTIONS **/
@@ -144,7 +144,16 @@ export const Json2Csv = function(options: FullJson2CsvOptions) {
 
         params.header = params.headerFields
             .map(function(field) {
-                const headerKey = fieldTitleMapKeys.includes(field) ? options.fieldTitleMap[field] : field;
+                let headerKey = field;
+
+                // If a custom field title was provided for this field, use that
+                if (fieldTitleMapKeys.includes(field)) {
+                    headerKey = options.fieldTitleMap[field];
+                } else if (!options.escapeHeaderNestedDots) { 
+                    // Otherwise, if the user doesn't want nested dots in keys to be escaped, then unescape them
+                    headerKey = headerKey.replace(/\\\./g, '.');
+                }
+
                 return wrapFieldValueIfNecessary(headerKey);
             })
             .join(options.delimiter.field);

src/types.ts

@@ -98,6 +98,12 @@ export interface Json2CsvOptions extends SharedConverterOptions {
    */
   emptyFieldValue?: unknown;
 
+  /**
+   * Should dots (`.`) appearing in header keys be escaped with a preceding slash (`\`)?
+   * @default true
+   */
+  escapeHeaderNestedDots?: boolean;
+
   /**
    *  Should nested objects be deep-converted to CSV
    *  @default true