#Transformer API

Transformers are used by the source plugins to parse content. They are automatically used as long as they are installed and found in package.json.

#Mime types

#transformer.mimeTypes()

A transformer must have a static mimeTypes method which returns an array of mime types the transformer should be able to parse.

#Parse content

#transformer.parse(source)

A transformer must also implement a parse method that will be executed be source plugins to parse content. The method must return a node.

#Add GraphQL fields

#transformer.extendNodeType()

Transformers can also extend nodes in the GraphQL schema with additional fields by implementing a extendNodeType method. The fields will only be added to nodes it has transformed.

#Example

class Transformer {
  static mimeTypes () {
    return ['application/json']
  }

  parse (source) {
    const { title, ...fields } = JSON.parse(source)

    return {
      title,
      fields
    }
  }

  extendNodeType ({ graphql }) {
    return {
      // custom GraphQL fields for transformed node
    }
  }
}

module.exports = Transformer