Format renamer patch

README.md

@@ -78,6 +78,32 @@ string
 })
 ```
 
+### create multiple formats from a single date
+
+By default the formatted date is output with the same key as the original date (so the original date gets replaced).
+
+It can be useful to output a single date in more than one format. This can be achieved by:
+- using the *array of objects* format for `dates`
+- adding copies of date objects which include an `out_key` property
+
+The following example re-uses the same `date` and outputs it in 2 formats named `dateNice`, `dateYear`.
+```js
+.use(dateFormatter({
+    dates: [
+        {
+            key: 'date',
+            format: 'MMMM DD, YYYY',
+            out_key: 'dateNice'
+        }, {
+            key: 'date',
+            format: 'YYYY',
+            out_key: 'dateYear'
+        }
+    ]
+})
+```
+(`out_key` can also be used to rename a date)
+
 ### format
 
 Any date format that `moment` accepts, defaults to `MMMM DD, YYYY`

lib/index.js

@@ -61,6 +61,7 @@ function plugin(options) {
     var dateKeys = DEFAULT_DATE_KEYS;
     var normalizedDateKeys;
     var formats;
+    var out_keys;
 
     if (isString(options.dates)) {
         dateKeys = [options.dates];
@@ -73,6 +74,9 @@ function plugin(options) {
         if (normalizedDateKeys.formats) {
             formats = normalizedDateKeys.formats;
         }
+        if (normalizedDateKeys.out_keys) {
+            out_keys = normalizedDateKeys.out_keys;
+        }
     }
 
     return function (files, metalsmith, done) {
@@ -85,11 +89,15 @@ function plugin(options) {
             transform(dateKeys, function (result, fKey, index) {
                 var time = result[fKey];
                 var localFormat = format;
+                var out_key = fKey;
                 if (formats && formats[index]) {
                     localFormat = formats[index];
                 }
+                if (out_keys && out_keys[index]) {
+                    out_key = out_keys[index];
+                }
                 if (time) {
-                    result[fKey] = moment.utc(time).format(localFormat);
+                    result[out_key] = moment.utc(time).format(localFormat);
                 }
             }, file);
 
@@ -108,6 +116,7 @@ function plugin(options) {
 function normalizeDateKeys(dates) {
     var keys = [];
     var formats = [];
+    var out_keys = [];
 
     dates.forEach(function (element) {
         if (isString(element)) {
@@ -119,11 +128,19 @@ function normalizeDateKeys(dates) {
             if (element.format) {
                 formats.push(element.format);
             }
+            if (element.out_key) {
+                out_keys.push(element.out_key);
+            } else {
+                // out_keys isn't always defined but we need to keep the
+                // array indices in sync, so push something falsey
+                out_keys.push(undefined);
+            }
         }
     });
 
     return {
         keys: !isEmpty(keys) ? keys : null,
-        formats: !isEmpty(formats) ? formats : null
+        formats: !isEmpty(formats) ? formats : null,
+        out_keys: !isEmpty(out_keys) ? out_keys : null
     };
 }