Forslag: billeder skal gemmes i Media/MediaSet, ikke BLOB

custom/knowledge/architecture/pictures-must-use-media-not-blob.md

@@ -0,0 +1,51 @@
+---
+bc-version: [all]
+domain: architecture
+keywords: [blob, media, mediaset, picture-field, image-field, table-design]
+technologies: [al]
+countries: [w1]
+application-area: [all]
+---
+
+# Pictures must be stored in a Media/MediaSet field, not BLOB
+
+## Description
+
+`BLOB` is still a valid AL field type for arbitrary binary data, but it is
+not the right choice for storing pictures or images. Microsoft's current
+recommendation is the `Media` field type for a single image, or
+`MediaSet` when a record needs several image variants (e.g. multiple
+sizes). Media/MediaSet integrate with the platform's picture control, the
+media repository, image caching, and thumbnail generation — none of which
+a plain `BLOB` field gets. A `BLOB` field storing a picture works, but it
+is the legacy approach: no caching, no thumbnail support, and no
+integration with the standard picture controls used across Business
+Central pages.
+
+`BLOB` remains the correct choice for genuinely arbitrary binary payloads
+that are not images and don't benefit from the media pipeline (e.g. a raw
+file attachment blob unrelated to picture rendering).
+
+## Best Practice
+
+```al
+field(50; Picture; Media)
+{
+    Caption = 'Picture';
+}
+```
+
+## Anti Pattern
+
+```al
+field(50; Picture; BLOB)
+{
+    Caption = 'Picture';
+}
+```
+
+A `BLOB` field named "Picture" compiles and stores the image bytes, but
+it misses the picture control integration, caching, and thumbnail
+generation that a `Media`/`MediaSet` field provides for free — the anti
+pattern is choosing `BLOB` for image storage out of habit rather than
+recognizing that the field is holding a picture, not generic binary data.