```ruby
class SourcePresenter
  attr_reader :source

  def initialize(source)
    @source = source
  end

  def as_json(opts = {})
    {
      id: source.id,
      name: source.name,
      citation: source.description,
      citation_id: source.citation_id,
      source_type: source.source_type,
      asco_abstract_id: source.asco_abstract_id,
      source_url: source.source_url,
      open_access: source.open_access,
      pmc_id: source.pmc_id,
      publication_date: publication_date,
      journal: source.journal,
      full_journal_title: source.full_journal_title,
      status: source.status,
      is_review: source.is_review?,
      clinical_trials: source.clinical_trials.map { |t| ClinicalTrialPresenter.new(t) },
    }
  end

  private
  def publication_date
    {}.tap do |date|
      if source.publication_year
        date[:year] =  source.publication_year
      end
      if source.publication_month
        date[:month] = source.publication_month
      end
      if source.publication_day
        date[:day] = source.publication_day
      end
    end
  end
end
```

Add evidence item count to source presenter
user
```ruby
class SourcePresenter
  attr_reader :source

  def initialize(source)
    @source = source
  end

  def as_json(opts = {})
    {
      id: source.id,
      name: source.name,
      citation: source.description,
      citation_id: source.citation_id,
      source_type: source.source_type,
      asco_abstract_id: source.asco_abstract_id,
      source_url: source.source_url,
      open_access: source.open_access,
      pmc_id: source.pmc_id,
      publication_date: publication_date,
      journal: source.journal,
      full_journal_title: source.full_journal_title,
      status: source.status,
      is_review: source.is_review?,
      clinical_trials: source.clinical_trials.map { |t| ClinicalTrialPresenter.new(t) },
      evidence_item_count: source.evidence_items.size,
    }
  end

  private
  def publication_date
    {}.tap do |date|
      if source.publication_year
        date[:year] =  source.publication_year
      end
      if source.publication_month
        date[:month] = source.publication_month
      end
      if source.publication_day
        date[:day] = source.publication_day
      end
    end
  end
end
```
assistant