Add sgid support

app/javascript/activetext/index.js

@@ -25,9 +25,10 @@ addEventListener("trix-attachment-add", event => {
       console.warn("Failed to store file for attachment", attachment, error)
     } else {
       console.log("Created blob for attachment", attributes, attachment)
-      const { signed_id } = attributes
-      const url = `${blobsURL}/${signed_id}/${encodeURIComponent(attachment.file.name)}`
-      attachment.setAttributes({ url, signed_id })
+      attachment.setAttributes({
+        url: `${blobsURL}/${attributes.signed_id}/${encodeURIComponent(attachment.file.name)}`,
+        sgid: attributes.attachable_sgid
+      })
     }
   })
 })

lib/active_text/attachable.rb

@@ -1,5 +1,9 @@
 module ActiveText
   module Attachable
+    extend ActiveSupport::Concern
+
+    LOCATOR_NAME = "attachable"
+
     class << self
       def from_node(node)
         if attachable = attachable_from_sgid(node["sgid"])
@@ -13,12 +17,48 @@ module ActiveText
         end
       end
 
+      def from_attachable_sgid(sgid, options = {})
+        method = sgid.is_a?(Array) ? :locate_many_signed : :locate_signed
+        record = GlobalID::Locator.public_send(method, sgid, options.merge(for: LOCATOR_NAME))
+        record or raise ActiveRecord::RecordNotFound
+      end
+
       private
         def attachable_from_sgid(sgid)
-          ::Attachable.from_attachable_sgid(sgid)
+          from_attachable_sgid(sgid)
         rescue ActiveRecord::RecordNotFound
           nil
         end
     end
+
+    class_methods do
+      def from_attachable_sgid(sgid)
+        ActiveText::Attachable.from_attachable_sgid(sgid, only: self)
+      end
+    end
+
+    def attachable_sgid
+      to_sgid(expires_in: nil, for: LOCATOR_NAME).to_s
+    end
+
+    def attachable_content_type
+      try(:content_type) || "application/octet-stream"
+    end
+
+    def previewable_attachable?
+      false
+    end
+
+    def as_json(*)
+      super.merge(attachable_sgid: attachable_sgid)
+    end
+
+    def to_active_text_attributes(attributes = {})
+      attributes.dup.tap do |attributes|
+        attributes[:sgid] = attachable_sgid
+        attributes[:content_type] = attachable_content_type
+        attributes[:previewable] = true if previewable_attachable?
+      end
+    end
   end
 end

lib/active_text/engine.rb

@@ -11,6 +11,18 @@ module ActiveText
       end
     end
 
+    initializer "active_text.active_storage_extension" do
+      require "active_storage/blob"
+
+      class ActiveStorage::Blob
+        include ActiveText::Attachable
+
+        def previewable_attachable?
+          representable?
+        end
+      end
+    end
+
     # FIXME: Aren't helpers supposed to load automatically?
     # https://github.com/rails/rails/issues/26627 ?
     initializer "active_text.helper" do