instructure/canvas-lms · error · ArgumentError

missing required attributes: #

Error message

missing required attributes: #{missing.to_a}

What it means

attr_config_validate runs after defaults are applied and asserts that every attribute declared known in the attr_config was supplied (or defaulted). If any known attribute has neither a value nor a default, ArgumentError lists the missing keys. It enforces that stream/index definitions are complete before use.

Solutions

1. Supply values for every attribute named in `missing required attributes:`
2. Add defaults via attr_config declarations so validation passes
3. Remove attributes from the attr_config declaration if they are no longer needed
4. Check recent changes to the stream/index class for newly required attributes

Example fix

// before
EventStream::Stream.new(aggregate: ...)
// after
EventStream::Stream.new(aggregate: ..., record: ..., attribute_data: ...)

missing = klass.attr_config_known - (given.keys | klass.attr_config_defaults.keys)
raise "missing: #{missing}" unless missing.empty?

begin
  stream = EventStream::Stream.new(**attrs)
rescue ArgumentError => e
  raise unless e.message.start_with?('missing required attributes')
  Rails.logger.error("Incomplete stream config: #{e.message}")
end

When it happens

Trigger: Instantiating an EventStream::Stream or Index whose class defines an attr_config attribute but neither passes a value for it at construction nor provides a default; calling attr_config_validate manually with a partially populated config.

Common situations: Forgetting a required field in a custom event stream definition; renaming an attribute in one place but not at all construction sites; a nil-vs-absent confusion where the key was never set at all.

Understand the failure class

Background: "missing required argument" and "the following required arguments were not provided": what required-argument errors mean and how to fix them — this error's family across 20 libraries.

Related errors

• An institutional tag category did not pass validation
• app '# ' must be one of: #
• cannot change column: captions - locked by Master Course
• Cannot validate existence for resource type: #
• Caption cannot be empty.

AI-assisted analysis of instructure/canvas-lms@1c9f0bb801 (2026-09-15). Data as JSON: /api/errors/9f77cc00b2cd25df. Report an issue: GitHub.

Appendix: source

Thrown at gems/event_stream/lib/event_stream/attr_config.rb:92

          value = typecast.call(name, value)
        end
        attr_config_values[name] = value
      end
    end
  end

  def attr_config_values
    @attr_config_values ||= {}
  end

  def attr_config_validate
    self.class.attr_config_defaults.each do |key, value|
      unless attr_config_values.key?(key)
        attr_config_values[key] = value
      end
    end
    missing = self.class.attr_config_known - attr_config_values.keys
    raise ArgumentError, "missing required attributes: #{missing.to_a}" unless missing.empty?
  end

  def self.included(base)
    base.extend(ClassMethods)
  end
end

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