Validate bookmark URL uniqueness

slices/micropub/repos/post_repo.rb

@@ -53,6 +53,12 @@ module Micropub
           .one
       end
 
+      def url_exists?(url)
+        !!posts
+          .where(url: url)
+          .one
+      end
+
       def find!(id)
         posts
           .by_pk(id)

slices/micropub/validation/posts/bookmark_contract.rb

@@ -2,6 +2,9 @@ module Micropub
   module Validation
     module Posts
       class BookmarkContract < Dry::Validation::Contract
+
+        include Deps["repos.post_repo"]
+
         params do
           required(:name).filled(:string)
           required(:content).maybe(:string)
@@ -14,6 +17,10 @@ module Micropub
           required(:photos).array(:hash)
           required(:cache).filled(:bool)
         end
+
+        rule(:url) do
+          key.failure("URL already bookmarked") if post_repo.url_exists?(values[:url])
+        end
       end
     end
   end