Is it possible to validate a field based on another field’s value in custom validation?

    {
      title: 'Has date end?',
      name: 'has_date_end',
      type: 'boolean',
      fieldset: 'dates',
    },
    {
      name: 'date_end',
      type: 'date',
      fieldset: 'dates',
      validation: Rule => Rule.custom(() => {
        return Rule.valueOfField('has_date_end')
          ? true
          : 'Please check "Has date end?" field'
      })
    },

{
  name: 'durationInMinutes',
  type: 'number',
  title: 'Duration of talk, in minutes',
  validation: Rule => Rule.custom((duration, context) => {
    const isShortTalk = duration && duration <= 10
    if (isShortTalk && context.document.talkType !== 'lightning') {
      return 'Only lightning talks should be 10 minutes or less'
    }
    
    return true
  })
}