Module: Export::CSV

Defined in:
lib/export/csv.rb

Overview

Code that translates scopes into downloadable tab-delimited CSV. Dependant on Postgresql.

Defined Under Namespace

Modules: Globi, TaxonNameOrigin

Class Method Summary collapse

Class Method Details

.copy_table(query) ⇒ Object

Returns Tempfile.

Parameters:

  • query —

    any ActiveRecord::Relation

Returns:

  • Tempfile



112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
 
# File 'lib/export/csv.rb', line 112

def self.copy_table(query)
  conn = ::Export.get_connection

  t = Tempfile.new
  q = "COPY ( #{query.to_sql} ) TO STDOUT WITH (FORMAT CSV, DELIMITER E'\t', HEADER, ENCODING 'UTF8')"

  conn.copy_data(q) do
    while row = conn.get_copy_data
      t.write(row.force_encoding('UTF-8'))
    end
  end

  t.rewind
  t
end

.delete_columns(tbl, columns = []) ⇒ Array

Returns delete the specified columns.

Parameters:

  • table (Array)
  • columns (Array) (defaults to: [])

Returns:

  • (Array) —

    delete the specified columns



69
70
71
72
73
74
75
76
77
 
# File 'lib/export/csv.rb', line 69

def self.delete_columns(tbl, columns = [])
  columns.each do |col|
    headers = tbl.collect { |c| c.first }
    if index = headers.index(col.to_s)
      tbl.delete_at(index)
    end
  end
  tbl
end

.generate_csv(scope, exclude_columns: [], header_converters: [], trim_rows: false, trim_columns: false, column_order: []) ⇒ String

translate a scope into a CSV table, with optional tweaks to the data

This is a very nice reference for future consideration:

http://collectiveidea.com/blog/archives/2015/03/05/optimizing-rails-for-memory-usage-part-3-pluck-and-database-laziness

Parameters:

  • scope (Scope)
  • exclude_columns (Array) (defaults to: []) —

    strings

  • header_converters (Array) (defaults to: [])
  • trim_rows (Boolean) (defaults to: false)
  • trim_columns (Boolean) (defaults to: false)

Returns:

  • (String) —

    in CSV format



16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
 
# File 'lib/export/csv.rb', line 16

def self.generate_csv(scope, exclude_columns: [], header_converters: [], trim_rows: false, trim_columns: false, column_order: [])

  column_names = scope.columns_hash.keys
  column_names = sort_column_headers(column_names, column_order.map(&:to_s)) if column_order.any?

  h = ::CSV.new(column_names.join(','), header_converters:, headers: true)
  h.read

  headers = ::CSV::Row.new(h.headers, h.headers, true).headers

  tbl = headers.map { |h| [h] }

  # Pluck rows is from postgresql_cursor gem
  #puts Rainbow('preparing data: ' + (Benchmark.measure do
  scope.pluck_rows(*column_names).each do |o|
    o.each_with_index do |value, index|
      tbl[index] << Utilities::Strings.sanitize_for_csv(value)
    end
    # If keys are not deterministic: .attributes.values_at(*column_names).collect{|v| Utilities::Strings.sanitize_for_csv(v) }
  end
  # end).to_s).yellow

  if !exclude_columns.empty?
    # puts Rainbow('deleting columns: ' + (Benchmark.measure {
    delete_columns(tbl, exclude_columns)
    # }).to_s).yellow
  end

  if trim_columns
    # puts Rainbow('trimming columns: ' + (Benchmark.measure {
    trim_columns(tbl)
    # }).to_s).yellow
  end

  # CSV::Converters are only available on read, not generate, so we can't use them here.
  output = StringIO.new
  # puts Rainbow('generating CSV: '+ (Benchmark.measure do
  (0..tbl.first.length-1).each do |row_index|
    row = tbl.collect { |c| c[row_index] }
    if trim_rows
      next unless row.detect { |c| c.present? } # Minimize checks by exiting ASAP.  Could benchmark vs. row.compact.blank?
    end
    output.puts ::CSV.generate_line(row, col_sep: "\t", encoding: Encoding::UTF_8)
  end
  # end).to_s).yellow

  output.string
end

.sort_column_headers(column_names = [], column_order = []) ⇒ Object

Sort order for columns

columns not in column order at added at the the *front* of the file



96
97
98
99
100
101
102
103
104
105
106
107
108
 
# File 'lib/export/csv.rb', line 96

def self.sort_column_headers(column_names = [], column_order = [])
  sorted = []
  unsorted = []
  column_names.each do |n|
    if p = column_order.index(n)
      sorted[p] = n
    else
      unsorted.push n
    end
  end

  unsorted + sorted
end

.trim_columns(table) ⇒ Array

Parameters:

  • table (Array) —

    remove columns without any non-#blank? values (of course doing this in the scope is better!) this is very slow, use a proper scope, and exclude_columns: [] options instead

Returns:

  • (Array) 


83
84
85
86
87
88
89
90
91
92
 
# File 'lib/export/csv.rb', line 83

def self.trim_columns(table)
  to_delete = []

  table.each_with_index do |col, index|
    to_delete << index unless col.inject { |_, c| break true if c.present? }
  end

  to_delete.each_with_index { |x, i| table.delete_at(x-i) }
  table
end