Add string representation to image Format() (#6608)

when checking on the currently registered Formats, e.g. with `get_image_formats()` the output is now easier to read.

CHANGELOG.txt

@@ -7,6 +7,7 @@ Changelog
  * StreamField values can now be modified in-place (Matt Westcott)
  * Added support for Python 3.9
  * Switch pagination icons to use SVG instead of icon fonts (Scott Cranfill)
+ * Added string representation to image Format class (Andreas Nüßlein)
  * Fix: Stop menu icon overlapping the breadcrumb on small viewport widths in page editor (Karran Besen)
  * Fix: Make sure document chooser pagination preserves the selected collection when moving between pages (Alex Sa)
 

docs/releases/2.12.rst

@@ -21,6 +21,7 @@ Other features
 
  * Added support for Python 3.9
  * Switch pagination icons to use SVG instead of icon fonts (Scott Cranfill)
+ * Added string representation to image Format class (Andreas Nüßlein)
 
 
 Bug fixes

wagtail/images/formats.py

@@ -13,6 +13,12 @@ class Format:
         self.classnames = classnames
         self.filter_spec = filter_spec
 
+    def __str__(self):
+        return f'"{self.name}", "{self.label}", "{self.classnames}", "{self.filter_spec}"'
+
+    def __repr__(self):
+        return f"Format({self})"
+
     def editor_attributes(self, image, alt_text):
         """
         Return additional attributes to go on the HTML element