Do not write non-String to response body when using custom_block_resu…

…lts plugin

Previously, the plugin would write non-nil/false values to the
response body, which is not supported unless the value is a
String.  Have unsupported_block_result return nil unless the
return value of the block is a string.

CHANGELOG

@@ -1,3 +1,7 @@
+= master
+
+* Do not write non-String to response body when using custom_block_results plugin (jeremyevans)
+
 = 3.86.0 (2024-11-12)
 
 * Add conditional_sessions plugin, for using the sessions plugin for only a subset of requests (jeremyevans)

lib/roda/plugins/custom_block_results.rb

@@ -28,7 +28,16 @@ module RodaPlugins
     #
     # Note that custom block result handling only occurs if the types
     # are not handled by Roda itself.  You cannot use this to modify
-    # the handling of nil, false, or string results.
+    # the handling of nil, false, or string results.  Additionally,
+    # if the response body has already been written to before the the
+    # route block exits, then the result of the block is ignored,
+    # and the related +handle_block_result+ block will not be called
+    # (this is standard Roda behavior).
+    # 
+    # The return value of the +handle_block_result+ block is written
+    # to the body if the block return value is a String, similar to
+    # standard Roda handling of block results.  Non-String return
+    # values are ignored.
     module CustomBlockResults
       def self.configure(app)
         app.opts[:custom_block_results] ||= {}
@@ -55,7 +64,15 @@ module RequestMethods
         # to get the block result.
         def unsupported_block_result(result)
           roda_class.opts[:custom_block_results].each do |klass, meth|
-            return scope.send(meth, result) if klass === result
+            if klass === result
+              result = scope.send(meth, result)
+
+              if String === result
+                return result
+              else
+                return
+              end
+            end
           end
 
           super

spec/plugin/custom_block_results_spec.rb

@@ -16,6 +16,16 @@
     end
   end
 
+  it "should handle blocks that do not return strings" do
+    2.times do
+      @app.handle_block_result(Symbol) do |s|
+        response.status = 201
+      end
+      status.must_equal 201
+      body.must_be_empty
+    end
+  end
+
   it "should handle other objects supporting ===" do
     @app.handle_block_result(/sy/) do |s|
       "x#{s}"