113 lines
2.4 KiB
Ruby
113 lines
2.4 KiB
Ruby
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# frozen_string_literal: true
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# Generates CSV when given a collection and a mapping.
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#
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# Example:
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#
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# columns = {
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# 'Title' => 'title',
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# 'Comment' => 'comment',
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# 'Author' => -> (post) { post.author.full_name }
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# 'Created At (UTC)' => -> (post) { post.created_at&.strftime('%Y-%m-%d %H:%M:%S') }
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# }
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#
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# CsvBuilder.new(@posts, columns).render
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#
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class CsvBuilder
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attr_reader :rows_written
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#
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# * +collection+ - The data collection to be used
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# * +header_to_hash_value+ - A hash of 'Column Heading' => 'value_method'.
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#
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# The value method will be called once for each object in the collection, to
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# determine the value for that row. It can either be the name of a method on
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# the object, or a lamda to call passing in the object.
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def initialize(collection, header_to_value_hash)
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@header_to_value_hash = header_to_value_hash
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@collection = collection
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@truncated = false
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@rows_written = 0
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end
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# Renders the csv to a string
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def render(truncate_after_bytes = nil)
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Tempfile.open(['csv']) do |tempfile|
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csv = CSV.new(tempfile)
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write_csv csv, until_condition: -> do
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truncate_after_bytes && tempfile.size > truncate_after_bytes
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end
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if block_given?
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yield tempfile
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else
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tempfile.rewind
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tempfile.read
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end
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end
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end
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def truncated?
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@truncated
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end
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def rows_expected
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if truncated? || rows_written == 0
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@collection.count
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else
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rows_written
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end
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end
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def status
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{
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truncated: truncated?,
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rows_written: rows_written,
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rows_expected: rows_expected
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}
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end
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private
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def headers
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@headers ||= @header_to_value_hash.keys
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end
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def attributes
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@attributes ||= @header_to_value_hash.values
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end
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def row(object)
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attributes.map do |attribute|
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if attribute.respond_to?(:call)
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excel_sanitize(attribute.call(object))
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else
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excel_sanitize(object.public_send(attribute)) # rubocop:disable GitlabSecurity/PublicSend
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end
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end
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end
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def write_csv(csv, until_condition:)
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csv << headers
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@collection.find_each do |object|
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csv << row(object)
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@rows_written += 1
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if until_condition.call
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@truncated = true
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break
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end
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end
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end
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def excel_sanitize(line)
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return if line.nil?
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line = ["'", line].join if line =~ /^[=\+\-@;]/
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line
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end
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end
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