1 files changed, 29 insertions, 2 deletions
diff --git a/actionpack/lib/action_dispatch/middleware/exception_wrapper.rb b/actionpack/lib/action_dispatch/middleware/exception_wrapper.rb
index f05c69137b..fb2b2bd3b0 100644
--- a/actionpack/lib/action_dispatch/middleware/exception_wrapper.rb
+++ b/actionpack/lib/action_dispatch/middleware/exception_wrapper.rb
@@ -31,11 +31,12 @@ module ActionDispatch
       "ActionController::MissingExactTemplate" => "missing_exact_template",
     )
 
-    attr_reader :backtrace_cleaner, :exception, :line_number, :file
+    attr_reader :backtrace_cleaner, :exception, :wrapped_causes, :line_number, :file
 
     def initialize(backtrace_cleaner, exception)
       @backtrace_cleaner = backtrace_cleaner
       @exception = original_exception(exception)
+      @wrapped_causes = wrapped_causes_for(exception, backtrace_cleaner)
 
       expand_backtrace if exception.is_a?(SyntaxError) || exception.cause.is_a?(SyntaxError)
     end
@@ -66,7 +67,11 @@ module ActionDispatch
       full_trace_with_ids = []
 
       full_trace.each_with_index do |trace, idx|
-        trace_with_id = { id: idx, trace: trace }
+        trace_with_id = {
+          exception_object_id: @exception.object_id,
+          id: idx,
+          trace: trace
+        }
 
         if application_trace.include?(trace)
           application_trace_with_ids << trace_with_id
@@ -99,6 +104,18 @@ module ActionDispatch
       end
     end
 
+    def trace_to_show
+      if traces["Application Trace"].empty? && rescue_template != "routing_error"
+        "Full Trace"
+      else
+        "Application Trace"
+      end
+    end
+
+    def source_to_show_id
+      (traces[trace_to_show].first || {})[:id]
+    end
+
     private
 
       def backtrace
@@ -113,6 +130,16 @@ module ActionDispatch
         end
       end
 
+      def causes_for(exception)
+        return enum_for(__method__, exception) unless block_given?
+
+        yield exception while exception = exception.cause
+      end
+
+      def wrapped_causes_for(exception, backtrace_cleaner)
+        causes_for(exception).map { |cause| self.class.new(backtrace_cleaner, cause) }
+      end
+
       def clean_backtrace(*args)
         if backtrace_cleaner
           backtrace_cleaner.clean(backtrace, *args)