Parsers

Parsers

parsed_ingredients and parsed_nutrients come from parsers. The bundled ones work with no setup. Add your own when a site writes its ingredients or nutrients in a way they do not read.

Writing a parser

A parser is anything that answers call(text, language:). It gets one ingredient line or one nutrient value, and the language tag of the recipe, such as "en-US" or nil. It returns a hash, or nil when it cannot read the text.

• An ingredient parser returns amount, unit and name.
• A nutrient parser returns unit and amount. It can add name, which otherwise is the key the value came under, such as "calories".

A key left out is nil.

grams_only = lambda do |text, language:|
  amount = text[/\A(\d+)\s*g\b/, 1]
  next nil unless amount

  { amount: amount.to_f, unit: "g", name: text.sub(/\A\d+\s*g\s*/, "") }
end

Adding it

Put your parser in front of the bundled one:

RecipeScrapers.configure do |config|
  config.parsers[:ingredients].unshift(grams_only)
end

The parsers are tried in order, and the first one that returns a hash wins. Every line yours returns nil for still goes to the bundled parser. Only :ingredients and :nutrients take parsers.

When a parser fails

A parser that raises, or returns a key the field does not have, is skipped for that line, and the next parser is tried. The error goes to error_tracker, which raises it again by default. To report it and carry on instead:

RecipeScrapers.configure do |config|
  config.error_tracker = ->(error) { warn(error.full_message) }
end