Null Reference Error when preparing aruments

[nealblomfield]

Describe the bug

InputObject#validate_for generates a NoMethodError: undefined method `[]' for nil because it is being passed a nil context (https://github.com/rmosolgo/graphql-ruby/blob/v2.4.15/lib/graphql/schema/input_object.rb#L109). Walking back up the call stack shows that:

• Argument#recursively_prepare_input_argument (https://github.com/rmosolgo/graphql-ruby/blob/v2.4.15/lib/graphql/schema/argument.rb#L410) passes the context unchecked
• Argument#prepare_value passes the context which may default to nil (https://github.com/rmosolgo/graphql-ruby/blob/v2.4.15/lib/graphql/schema/argument.rb#L220)
• InputObject#initialize specifically calls Argument#prepare_value when context is nil https://github.com/rmosolgo/graphql-ruby/blob/v2.4.15/lib/graphql/schema/input_object.rb#L41

Versions

graphql version: 2.4.15
rails (or other framework): 7.2.2.1

GraphQL schema
Nothing relevant

GraphQL query
Nothing relevant

Steps to reproduce

Steps to reproduce the behavior

Expected behavior
The code does not throw a no method error on nil when preparing arguments

Actual behavior
The code threw a no method error on nil when preparing arguments

Click to view exception backtrace

["graphql-2.4.15/lib/graphql/schema/input_object.rb:109:in `validate_for'",
 "graphql-2.4.15/lib/graphql/schema/argument.rb:410:in `recursively_prepare_input_object'",
 "graphql-2.4.15/lib/graphql/schema/argument.rb:408:in `block in recursively_prepare_input_object'",
 "graphql-2.4.15/lib/graphql/schema/argument.rb:408:in `map'",
 "graphql-2.4.15/lib/graphql/schema/argument.rb:408:in `recursively_prepare_input_object'",
 "graphql-2.4.15/lib/graphql/schema/argument.rb:220:in `prepare_value'",
 "graphql-2.4.15/lib/graphql/schema/input_object.rb:41:in `block in initialize'",
 "graphql-2.4.15/lib/graphql/schema/input_object.rb:35:in `each'",
 "graphql-2.4.15/lib/graphql/schema/input_object.rb:35:in `initialize'",
 "graphql-2.4.15/lib/graphql/schema/input_object.rb:235:in `new'",
 "graphql-2.4.15/lib/graphql/schema/input_object.rb:235:in `block in coerce_input'",
 "graphql-2.4.15/lib/graphql/execution/interpreter/runtime.rb:777:in `minimal_after_lazy'",
 "graphql-2.4.15/lib/graphql/execution/interpreter/runtime.rb:774:in `block in minimal_after_lazy'",
 "graphql-2.4.15/lib/graphql/execution/lazy.rb:30:in `value'",
 "graphql-2.4.15/lib/graphql/schema.rb:1628:in `public_send'",
 "graphql-2.4.15/lib/graphql/schema.rb:1628:in `sync_lazy'",
 "graphql-2.4.15/lib/graphql/execution/interpreter/runtime.rb:772:in `block in minimal_after_lazy'",
 "graphql-2.4.15/lib/graphql/execution/lazy.rb:30:in `value'",
 "graphql-2.4.15/lib/graphql/execution/lazy.rb:59:in `block (2 levels) in all'",
 "graphql-2.4.15/lib/graphql/execution/lazy.rb:59:in `map'",
 "graphql-2.4.15/lib/graphql/execution/lazy.rb:59:in `block in all'",
 "graphql-2.4.15/lib/graphql/execution/lazy.rb:30:in `value'",
 "graphql-2.4.15/lib/graphql/execution/lazy.rb:51:in `block in then'",
 "graphql-2.4.15/lib/graphql/execution/lazy.rb:30:in `value'",
 "graphql-2.4.15/lib/graphql/schema.rb:1628:in `public_send'",
 "graphql-2.4.15/lib/graphql/schema.rb:1628:in `sync_lazy'",
 "graphql-2.4.15/lib/graphql/execution/interpreter/runtime.rb:807:in `block (2 levels) in after_lazy'",
 "graphql-2.4.15/lib/graphql/tracing/trace.rb:111:in `execute_field_lazy'",
 "graphql-2.4.15/lib/graphql/tracing/data_dog_trace.rb:118:in `block in execute_field_lazy'",
 "graphql-2.4.15/lib/graphql/tracing/data_dog_trace.rb:104:in `block in execute_field_span'",
 "datadog-2.12.2/lib/datadog/tracing/trace_operation.rb:226:in `block in measure'",
 "datadog-2.12.2/lib/datadog/tracing/span_operation.rb:152:in `measure'",
 "datadog-2.12.2/lib/datadog/tracing/trace_operation.rb:226:in `measure'",
 "datadog-2.12.2/lib/datadog/tracing/tracer.rb:411:in `start_span'",
 "datadog-2.12.2/lib/datadog/tracing/tracer.rb:166:in `block in trace'",
 "datadog-2.12.2/lib/datadog/tracing/context.rb:45:in `activate!'",
 "datadog-2.12.2/lib/datadog/tracing/tracer.rb:165:in `trace'",
 "datadog-2.12.2/lib/datadog/tracing.rb:30:in `trace'",
 "graphql-2.4.15/lib/graphql/tracing/data_dog_trace.rb:96:in `execute_field_span'",
 "graphql-2.4.15/lib/graphql/tracing/data_dog_trace.rb:117:in `execute_field_lazy'",
 "graphql-2.4.15/lib/graphql/tracing/notifications_trace.rb:38:in `block in execute_field_lazy'",
 "activesupport-7.2.2.1/lib/active_support/notifications.rb:212:in `instrument'",
 "graphql-2.4.15/lib/graphql/tracing/notifications_trace.rb:38:in `execute_field_lazy'",
 "graphql-2.4.15/lib/graphql/execution/interpreter/runtime.rb:806:in `block in after_lazy'",
 "graphql-2.4.15/lib/graphql/execution/lazy.rb:30:in `value'",
 "graphql-2.4.15/lib/graphql/execution/interpreter/resolve.rb:27:in `each'",
 "graphql-2.4.15/lib/graphql/execution/interpreter/resolve.rb:27:in `block in resolve_each_depth'",
 "graphql-2.4.15/lib/graphql/dataloader/null_dataloader.rb:19:in `append_job'",
 "graphql-2.4.15/lib/graphql/execution/interpreter/resolve.rb:26:in `resolve_each_depth'",
 "graphql-2.4.15/lib/graphql/execution/interpreter.rb:104:in `block (3 levels) in run_all'",
 "graphql-2.4.15/lib/graphql/tracing/trace.rb:89:in `execute_query_lazy'",
 "graphql-2.4.15/lib/graphql/tracing/data_dog_trace.rb:51:in `block in execute_query_lazy'",
 "datadog-2.12.2/lib/datadog/tracing/trace_operation.rb:226:in `block in measure'",
 "datadog-2.12.2/lib/datadog/tracing/span_operation.rb:152:in `measure'",
 "datadog-2.12.2/lib/datadog/tracing/trace_operation.rb:226:in `measure'",
 "datadog-2.12.2/lib/datadog/tracing/tracer.rb:411:in `start_span'",
 "datadog-2.12.2/lib/datadog/tracing/tracer.rb:166:in `block in trace'",
 "datadog-2.12.2/lib/datadog/tracing/context.rb:45:in `activate!'",
 "datadog-2.12.2/lib/datadog/tracing/tracer.rb:165:in `trace'",
 "datadog-2.12.2/lib/datadog/tracing.rb:30:in `trace'",
 "graphql-2.4.15/lib/graphql/tracing/data_dog_trace.rb:43:in `execute_query_lazy'",
 "graphql-2.4.15/lib/graphql/tracing/notifications_trace.rb:38:in `block in execute_query_lazy'",
 "activesupport-7.2.2.1/lib/active_support/notifications.rb:212:in `instrument'",
 "graphql-2.4.15/lib/graphql/tracing/notifications_trace.rb:38:in `execute_query_lazy'",
 "graphql-2.4.15/lib/graphql/execution/interpreter.rb:103:in `block (2 levels) in run_all'",
 "graphql-2.4.15/lib/graphql/dataloader/null_dataloader.rb:19:in `append_job'",
 "graphql-2.4.15/lib/graphql/execution/interpreter.rb:94:in `block in run_all'",
 "graphql-2.4.15/lib/graphql/tracing/trace.rb:81:in `execute_multiplex'",
 "graphql-2.4.15/lib/graphql/tracing/data_dog_trace.rb:63:in `block in execute_multiplex'",
 "datadog-2.12.2/lib/datadog/tracing/trace_operation.rb:226:in `block in measure'",
 "datadog-2.12.2/lib/datadog/tracing/span_operation.rb:152:in `measure'",
 "datadog-2.12.2/lib/datadog/tracing/trace_operation.rb:226:in `measure'",
 "datadog-2.12.2/lib/datadog/tracing/tracer.rb:411:in `start_span'",
 "datadog-2.12.2/lib/datadog/tracing/tracer.rb:166:in `block in trace'",
 "datadog-2.12.2/lib/datadog/tracing/context.rb:45:in `activate!'",
 "datadog-2.12.2/lib/datadog/tracing/tracer.rb:165:in `trace'",
 "datadog-2.12.2/lib/datadog/tracing.rb:30:in `trace'",
 "graphql-2.4.15/lib/graphql/tracing/data_dog_trace.rb:43:in `execute_multiplex'",
 "graphql-2.4.15/lib/graphql/tracing/notifications_trace.rb:38:in `block in execute_multiplex'",
 "activesupport-7.2.2.1/lib/active_support/notifications.rb:210:in `block in instrument'",
 "activesupport-7.2.2.1/lib/active_support/notifications/instrumenter.rb:58:in `instrument'",
 "activesupport-7.2.2.1/lib/active_support/notifications.rb:210:in `instrument'",
 "graphql-2.4.15/lib/graphql/tracing/notifications_trace.rb:38:in `execute_multiplex'",
 "app/graphql/tracing/actual_complexity.rb:19:in `execute_multiplex'",
 "graphql-batch-0.6.0/lib/graphql/batch/setup_multiplex.rb:24:in `execute_multiplex'",
 "graphql-2.4.15/lib/graphql/execution/interpreter.rb:42:in `run_all'",
 "graphql-2.4.15/lib/graphql/schema.rb:1573:in `multiplex'",
 "graphql-2.4.15/lib/graphql/schema.rb:1549:in `execute'",
 ]```

</details>

**Additional context**

[rmosolgo]

Hey, thanks for the detailed report and sorry for the trouble! I just moved this code around (#5285) but my test suite must be missing some coverage for the case you described here. I'll take a look soon and follow up here.

[nealblomfield]

#5321 will not fix this bug because the block of code can be run when the context is nil. Please reopen this bug report.

            if arg_defn.prepare.is_a?(Symbol) || context.nil?
              prepared_value = arg_defn.prepare_value(self, @ruby_style_hash[ruby_kwargs_key])
              prepared_value = arg_defn.prepare_value(self, @ruby_style_hash[ruby_kwargs_key], context: context)
              overwrite_argument(ruby_kwargs_key, prepared_value)
            end

[rmosolgo]

will not

Just to clarify, did you try the new version and find that the same thing went wrong? If you haven't tried it, please do, and let me know what you find!

I replicated this error in a test, using the clues from the backtrace, and I think the reason it ended up here is because arg_defn.prepare was a Symbol. The patch in #5321 fixed my replication example.

I think the context.nil? check is for some legacy usages of InputObject.new, but not used in normal execution.

[nealblomfield]

Looks like it has fixed the bug that we were seeing. Thanks.

[rmosolgo]

Awesome, thanks again for the detailed report and please let me know if it gives you an more trouble!