1 files changed, 32 insertions, 2 deletions
diff --git a/app/graphql/types/base_field.rb b/app/graphql/types/base_field.rb
index 8c8b8a82d3e..15331129134 100644
--- a/app/graphql/types/base_field.rb
+++ b/app/graphql/types/base_field.rb
@@ -7,10 +7,40 @@ module Types
     DEFAULT_COMPLEXITY = 1
 
     def initialize(*args, **kwargs, &block)
-      # complexity is already defaulted to 1, but let's make it explicit
-      kwargs[:complexity] ||= DEFAULT_COMPLEXITY
+      kwargs[:complexity] ||= field_complexity(kwargs[:resolver_class])
 
       super(*args, **kwargs, &block)
     end
+
+    private
+
+    def field_complexity(resolver_class)
+      if resolver_class
+        field_resolver_complexity
+      else
+        DEFAULT_COMPLEXITY
+      end
+    end
+
+    def field_resolver_complexity
+      # Complexity can be either integer or proc. If proc is used then it's
+      # called when computing a query complexity and context and query
+      # arguments are available for computing complexity.  For resolvers we use
+      # proc because we set complexity depending on arguments and number of
+      # items which can be loaded.
+      proc do |ctx, args, child_complexity|
+        page_size = @max_page_size || ctx.schema.default_max_page_size
+        limit_value = [args[:first], args[:last], page_size].compact.min
+
+        # Resolvers may add extra complexity depending on used arguments
+        complexity = child_complexity + self.resolver&.try(:resolver_complexity, args).to_i
+
+        # Resolvers may add extra complexity depending on number of items being loaded.
+        multiplier = self.resolver&.try(:complexity_multiplier, args).to_f
+        complexity += complexity * limit_value * multiplier
+
+        complexity.to_i
+      end
+    end
   end
 end