Merge pull request #23 from maks/lists-sortby

List sorting and date formating function

README.md

@@ -182,18 +182,16 @@ Listing files are in yaml format with the following parameters supported: `path`
 
 The `path` is a path relative to `.dsg/html/_content`.
 The `filter` specifies which files to list within the given path.
-The `sort_by` specifies a property.
+The `sort_by` specifies a property **AND** the `ASC` or `DESC`.
 
-eg.
+eg. to sort in chronological descending order based on a front-matter property called `pub_date`
 
 ```yaml
 path: blog
 filter: "*.md"
-sort_by: lastModified
+sort_by: pub_date DESC
 ```
 
-**note:** `sortby` not yet implemented.
-
 **DSG** injects your listings into a global `_lists` variable. For each file all of the files YAML front-matter properties are available along with the files:
 
 * `filename`:  the files name without extension.
@@ -336,6 +334,25 @@ dart: ->usage.badge.dart
 ---  
 ```
 
+## Template Functions
+
+Mustache provides for the use of "lambdas" which are essentially names functions that can be accessed in templates using the section syntax.
+The currently available functions in DSG are listed below.
+
+### formatDate
+
+Allows formating either a hard coded string or another template variable written in the format `yyyy-MM-dd` the function will ouput the it using the format specified in `date_format` in `site.yaml`.
+
+eg. given in site.yaml a `date_format: dd MMM yyyy` and then a variable defined in your front-matter like `article_date: 2020-01-26`
+and then a template with:
+```mustache
+
+Article published on: {{# formatDate }} {{ date }} {{/ formatDate }} 
+
+```
+will output: `Article published on: 26 Jan 2020`
+
+
 ## SASS
 If DSG finds a .scss file in your output dir (web) it compiles it to the corresponding .css file.      
 Install instruction for SASS can be found [here](https://sass-lang.com/install)  

lib/dsg.dart

@@ -28,6 +28,7 @@ part 'src/config.dart';
 part 'src/generator.dart';
 part 'src/init.dart';
 part 'src/options.dart';
+part 'src/dates.dart';
 
 bool _runsOnOSX() => (SysInfo.operatingSystemName == 'Mac OS X');
 

lib/src/dates.dart

@@ -0,0 +1,13 @@
+part of dsg;
+
+String _parseDate(String dateStr, String parseFormat, String outputFormat) {
+  final _logger = Logger('dsg.dates');
+
+  try {
+    final date = DateFormat(parseFormat).parseLoose(dateStr.trim());
+    return DateFormat(outputFormat).format(date);
+  } catch (e) {
+    _logger.warning('FAILED to parse date: $dateStr $e');
+    return dateStr;
+  }
+}

lib/src/generator.dart

@@ -9,6 +9,8 @@ typedef TemplateRenderer = String Function(
 /// Resolved partial-names into mustache.Templates
 typedef PartialsResolver = mustache.Template Function(String name);
 
+String _outputFormat = 'MMMM dd yyyy';
+
 /// Can be set to define a custom [rendering function](TemplateRenderer) to handle your template files
 /// and use any templating language of your choice.
 ///
@@ -19,6 +21,13 @@ TemplateRenderer renderTemplate =
   final template = mustache.Template(source,
       htmlEscapeValues: false, partialResolver: resolver, lenient: true);
 
+  final inFormat = 'yyyy-MM-dd';
+
+  final formatDate = (mustache.LambdaContext ctx) =>
+      '${_parseDate(ctx.renderString(), inFormat, _outputFormat)}';
+
+  options['formatDate'] = formatDate;
+
   return template.renderString(options);
 };
 
@@ -57,6 +66,8 @@ class Generator {
 
     final dataMap = _getDataMap(dataFiles);
 
+    _outputFormat = config.dateformat;
+
     _logger.info('Listings... ${listingsMap?.keys}');
 
     _logger.info('Generating .html files...');

lib/src/listings.dart

@@ -33,8 +33,19 @@ Future<Map<String, List<Map>>> getListingsMap(
   await listingsMap.forEach((key, value) async {
     listings[key] = await value;
 
-    // TODO:
-    _logger.info('SORT listing: $key BY: ${configsMap[key].sortby}');
+    final sortBy = configsMap[key].sortby.split(' ')[0];
+    final sortDirection = configsMap[key].sortby.split(' ')[1];
+
+    final asc = (dynamic a, dynamic b) =>
+        a[sortBy].toString().compareTo(b[sortBy].toString());
+    final desc = (dynamic a, dynamic b) =>
+        b[sortBy].toString().compareTo(a[sortBy].toString());
+
+    final sortFunction = (sortDirection == 'DESC') ? desc : asc;
+
+    _logger.info('SORT listing: $key BY: $sortBy');
+
+    listings[key].sort(sortFunction);
   });
   return listings;
 }