Add fragment proc for list names

This allows us to identify a fragment that depends on item context in a list

Author: jho406

lib/props_template/extensions/partial_renderer.rb

@@ -152,6 +152,10 @@ def refine_options(options, item = nil)
         locals[as] = item
 
         if (fragment_name = rest[:fragment])
+          if item && ::Proc === fragment_name
+            fragment_name = fragment_name.call(item)
+          end
+
           rest[:fragment] = fragment_name.to_s
         end
       end
@@ -163,3 +167,4 @@ def refine_options(options, item = nil)
     end
   end
 end
+

spec/extensions/fragments_spec.rb

@@ -170,4 +170,40 @@
       ]
     })
   end
+
+  it "renders an array of partials with fragments using a proc to derive the fragment key" do
+    json = render(<<~PROPS)
+      klass = Struct.new(:email, :id)
+
+      users = [
+        klass.new('[email protected]', 1),
+        klass.new('[email protected]', 2)
+      ]
+
+      json.data do
+        opts = {
+          partial: ['person', fragment: -> (item) { item.email } ]
+        }
+        json.array! users, opts do
+        end
+      end
+
+      json.fragments json.fragments!
+    PROPS
+
+    expect(json).to eql_json({
+      data: [
+        {
+          email: "[email protected]",
+        },
+        {
+          email: "[email protected]",
+        }
+      ],
+      fragments: [
+        {type: "[email protected]", partial: "person", path: "data.0"},
+        {type: "[email protected]", partial: "person", path: "data.1"}
+      ]
+    })
+  end
 end