Merge pull request MWDelaney#23 from xaqrox/filter

Add filter support for block data.

README.md

@@ -59,3 +59,10 @@ Add blade templates to `views/blocks` which get and use ACF data. Each template
 
 ## Creating ACF fields
 Once a block is created you'll be able to assign ACF fields to it using the standard Custom Fields interface in WordPress. We recommend using [sage-advanced-custom-fields](https://github.com/MWDelaney/sage-advanced-custom-fields) to keep your ACF fields in version control with Sage.
+
+## Filter block data
+Block data can be altered via the 'sage/blocks/[block-name]/data' filter. For example, if your block template is called `my-block.blade.php`, you can alter the data thusly:
+
+```php
+add_filter('sage/blocks/my-block/data', function ($block) { // Do your thing here. });
+```

sage-acf-gutenberg-blocks.php

@@ -143,7 +143,14 @@ function sage_blocks_callback($block, $content = '', $is_preview = false, $post_
     $block['is_preview'] = $is_preview;
     $block['content'] = $content;
     $block['slug'] = $slug;
-    $block['classes'] = implode(' ', [$block['slug'], $block['className'], 'align'.$block['align']]);
+    // Send classes as array to filter for easy manipulation.
+    $block['classes'] = [$slug, $block['className'], 'align'.$block['align']];
+
+    // Filter the block data.
+    $block = apply_filters("sage/blocks/$slug/data", $block);
+
+    // Join up the classes.
+    $block['classes'] = implode(' ', array_filter($block['classes']));
 
     // Use Sage's template() function to echo the block and populate it with data
     echo \App\template("blocks/${slug}", ['block' => $block]);