Prompt
Check for nil values early in methods and handle them gracefully before they can cause runtime errors or trigger expensive operations. This prevents NoMethodError exceptions and improves performance by avoiding unnecessary processing.
Key patterns to implement:
- Add nil checks at the beginning of methods before calling methods on potentially nil objects
- Use early returns to exit gracefully when required values are missing
- Place nil validations before expensive operations like database queries or Redis locks
- Use conditional access patterns when objects might be nil
Example of the problem:
def effective?
published? && effective_date.past? # NoMethodError if effective_date is nil
end
Example of the solution:
def accept_embedded_quote_request
quoted_status_uri = value_or_id(@object['object'])
quoting_status_uri = value_or_id(@object['instrument'])
approval_uri = value_or_id(first_of_value(@json['result']))
return if quoted_status_uri.nil? || quoting_status_uri.nil? || approval_uri.nil?
# Continue with expensive operations only after nil validation
with_redis_lock("announce:#{value_or_id(@object)}") do
# ... rest of method
end
end
For conditional access to potentially nil objects:
# Safe conditional access
cached[key] || (uncached[shortcode] if uncached)
# Safe method checking
params[scope].respond_to?(:[]) && params[scope][:password].present?