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Deterministic Cache Keys for Collections

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                  class CacheKeys
  def self.snips_index(member:, params:)
    parts = {
      member_id: member&.id,
      q: params[:q].to_s,
      tag: params[:tag].to_s,
      page: params[:page].to_s
    }

    "snips:index:v2:#{Digest::SHA1.hexdigest(parts.to_json)}"
  end
end

                  key = CacheKeys.snips_index(member: current_member, params: params)
@snips = Rails.cache.fetch(key, expires_in: 2.minutes) do
  Snip.by_active.page(params[:page])
end

When caching lists, include inputs that change the list (filters, page, member permissions). A deterministic cache key function prevents subtle “wrong user saw wrong list” bugs.

Sarah Chen

More from Sarah Chen

Deterministic Cache Keys for Collections

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More from Sarah Chen