Incorrect function argument leads to undefined method 'size'

[keestux]

The bug was introduced in this commit: 0b0a72f right before v3.8.0 was created.

There are two uses of full_field_name and only one was corrected modified in that commit. The remaining full_field_name that needs fixing is at line 114 lib/fit4ruby/FitMessageRecord.rb

        field_name = field_description.full_field_name(fit_entity)

That should have been

        field_name = field_description.full_field_name(fit_entity.top_level_record.developer_data_ids)

Still that is not enough to be able to read FIT files of my Wahoo device. The following problem area is here in lib/fit4ruby/FieldDescription.rb:

      app_id = developer_data_ids[@developer_data_index].application_id
      # Convert the byte array with the app ID into a 16 character hex string.
      app_id_str = app_id.map { |i| '%02X' % i }.join('')
      @full_field_name =
        "#{@field_name.gsub(/[^A-Za-z0-9_]/, '_')}_#{app_id_str}"

The thing is, my Wahoo device does not have a application_id.
I'm not sure what the best solution is. I've replaced the code with

      if (app_id = developer_data_ids[@developer_data_index].application_id)
        # Convert the byte array with the app ID into a 16 character hex string.
        id_str = app_id.map { |i| '%02X' % i }.join('')
        @full_field_name =
            "#{@field_name.gsub(/[^A-Za-z0-9_]/, '_')}_#{id_str}"
      elsif (manf_id = developer_data_ids[@developer_data_index].manufacturer_id)
        id_str = '%02X' % manf_id
        @full_field_name = @field_name
      else
        id_str = ""
        @full_field_name = @field_name
      end

At least I can now read my FIT file.

[keestux]

@jtanium You have forked this repo and added support for Coros. You must have run into that .size problem as well. I see that you more experienced with Ruby then I am. Can you have a look at my first remark in this issue?

[jtanium]

Hey @keestux -- I no longer work for the company where I was doing that work, and it's all pretty fuzzy. I used Claude to help me review your fixes and to create this reply. The usual warnings apply.

Bug 1 — wrong argument in FitMessageRecord.rb

Your diagnosis is correct. Line 114 passes fit_entity (a FitFileEntity object) where full_field_name expects the developer data IDs array. The fix:

field_name = field_description.full_field_name(fit_entity.top_level_record.developer_data_ids)

Interestingly, FieldDescription#create_global_definition already calls full_field_name with the right argument, so this was a case of one call site getting updated in 0b0a72f and the other being missed.

Also worth noting: once full_field_name crashes, field_name is nil for the rest of that loop iteration, and both obj.set(field_name, value) and the fields_dump block use it without a nil guard. So this is a hard crash, not just silent bad data.

Bug 2 — missing application_id on Wahoo devices

Your logic in FieldDescription.rb looks right. One small thing: I pulled the full method and it ends right after setting @full_field_name, so id_str in the elsif and else branches is dead code — it's assigned but never referenced. Since those two branches do the same thing anyway, I'd simplify:

dev_data = developer_data_ids[@developer_data_index]

if (app_id = dev_data.application_id)
  id_str = app_id.map { |i| '%02X' % i }.join('')
  @full_field_name = "#{@field_name.gsub(/[^A-Za-z0-9_]/, '_')}_#{id_str}"
else
  # Some devices (e.g. Wahoo) omit application_id; use the field name as-is.
  @full_field_name = @field_name
end

As I said, I no longer have access to the Coros files I used when I wrote that fork, so I can't verify. But your logic looks solid.

[keestux]

@jtanium Thanks