1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
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
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
|
== Recipes for Generating \CSV
These recipes are specific code examples for specific \CSV generating tasks.
For other recipes, see {Recipes for CSV}[./recipes_rdoc.html].
All code snippets on this page assume that the following has been executed:
require 'csv'
=== Contents
- {Output Formats}[#label-Output+Formats]
- {Generating to a String}[#label-Generating+to+a+String]
- {Recipe: Generate to String with Headers}[#label-Recipe-3A+Generate+to+String+with+Headers]
- {Recipe: Generate to String Without Headers}[#label-Recipe-3A+Generate+to+String+Without+Headers]
- {Generating to a File}[#label-Generating+to+a+File]
- {Recipe: Generate to File with Headers}[#label-Recipe-3A+Generate+to+File+with+Headers]
- {Recipe: Generate to File Without Headers}[#label-Recipe-3A+Generate+to+File+Without+Headers]
- {Generating to IO an Stream}[#label-Generating+to+an+IO+Stream]
- {Recipe: Generate to IO Stream with Headers}[#label-Recipe-3A+Generate+to+IO+Stream+with+Headers]
- {Recipe: Generate to IO Stream Without Headers}[#label-Recipe-3A+Generate+to+IO+Stream+Without+Headers]
- {Converting Fields}[#label-Converting+Fields]
- {Recipe: Filter Generated Field Strings}[#label-Recipe-3A+Filter+Generated+Field+Strings]
- {Recipe: Specify Multiple Write Converters}[#label-Recipe-3A+Specify+Multiple+Write+Converters]
- {RFC 4180 Compliance}[#label-RFC+4180+Compliance]
- {Row Separator}[#label-Row+Separator]
- {Recipe: Generate Compliant Row Separator}[#label-Recipe-3A+Generate+Compliant+Row+Separator]
- {Recipe: Generate Non-Compliant Row Separator}[#label-Recipe-3A+Generate+Non-Compliant+Row+Separator]
- {Column Separator}[#label-Column+Separator]
- {Recipe: Generate Compliant Column Separator}[#label-Recipe-3A+Generate+Compliant+Column+Separator]
- {Recipe: Generate Non-Compliant Column Separator}[#label-Recipe-3A+Generate+Non-Compliant+Column+Separator]
- {Quote Character}[#label-Quote+Character]
- {Recipe: Generate Compliant Quote Character}[#label-Recipe-3A+Generate+Compliant+Quote+Character]
- {Recipe: Generate Non-Compliant Quote Character}[#label-Recipe-3A+Generate+Non-Compliant+Quote+Character]
=== Output Formats
You can generate \CSV output to a \String, to a \File (via its path), or to an \IO stream.
==== Generating to a \String
You can generate \CSV output to a \String, with or without headers.
===== Recipe: Generate to \String with Headers
Use class method CSV.generate with option +headers+ to generate to a \String.
This example uses method CSV#<< to append the rows
that are to be generated:
output_string = CSV.generate('', headers: ['Name', 'Value'], write_headers: true) do |csv|
csv << ['Foo', 0]
csv << ['Bar', 1]
csv << ['Baz', 2]
end
output_string # => "Name,Value\nFoo,0\nBar,1\nBaz,2\n"
===== Recipe: Generate to \String Without Headers
Use class method CSV.generate without option +headers+ to generate to a \String.
This example uses method CSV#<< to append the rows
that are to be generated:
output_string = CSV.generate do |csv|
csv << ['Foo', 0]
csv << ['Bar', 1]
csv << ['Baz', 2]
end
output_string # => "Foo,0\nBar,1\nBaz,2\n"
==== Generating to a \File
You can generate /CSV data to a \File, with or without headers.
===== Recipe: Generate to \File with Headers
Use class method CSV.open with option +headers+ generate to a \File.
This example uses method CSV#<< to append the rows
that are to be generated:
path = 't.csv'
CSV.open(path, 'w', headers: ['Name', 'Value'], write_headers: true) do |csv|
csv << ['Foo', 0]
csv << ['Bar', 1]
csv << ['Baz', 2]
end
p File.read(path) # => "Name,Value\nFoo,0\nBar,1\nBaz,2\n"
===== Recipe: Generate to \File Without Headers
Use class method CSV.open without option +headers+ to generate to a \File.
This example uses method CSV#<< to append the rows
that are to be generated:
path = 't.csv'
CSV.open(path, 'w') do |csv|
csv << ['Foo', 0]
csv << ['Bar', 1]
csv << ['Baz', 2]
end
p File.read(path) # => "Foo,0\nBar,1\nBaz,2\n"
==== Generating to an \IO Stream
You can generate \CSV data to an \IO stream, with or without headers.
==== Recipe: Generate to \IO Stream with Headers
Use class method CSV.new with option +headers+ to generate \CSV data to an \IO stream:
path = 't.csv'
File.open(path, 'w') do |file|
csv = CSV.new(file, headers: ['Name', 'Value'], write_headers: true)
csv << ['Foo', 0]
csv << ['Bar', 1]
csv << ['Baz', 2]
end
p File.read(path) # => "Name,Value\nFoo,0\nBar,1\nBaz,2\n"
===== Recipe: Generate to \IO Stream Without Headers
Use class method CSV.new without option +headers+ to generate \CSV data to an \IO stream:
path = 't.csv'
File.open(path, 'w') do |file|
csv = CSV.new(file)
csv << ['Foo', 0]
csv << ['Bar', 1]
csv << ['Baz', 2]
end
p File.read(path) # => "Foo,0\nBar,1\nBaz,2\n"
=== Converting Fields
You can use _write_ _converters_ to convert fields when generating \CSV.
==== Recipe: Filter Generated Field Strings
Use option <tt>:write_converters</tt> and a custom converter to convert field values when generating \CSV.
This example defines and uses a custom write converter to strip whitespace from generated fields:
strip_converter = proc {|field| field.respond_to?(:strip) ? field.strip : field }
output_string = CSV.generate(write_converters: strip_converter) do |csv|
csv << [' foo ', 0]
csv << [' bar ', 1]
csv << [' baz ', 2]
end
output_string # => "foo,0\nbar,1\nbaz,2\n"
==== Recipe: Specify Multiple Write Converters
Use option <tt>:write_converters</tt> and multiple custom converters
to convert field values when generating \CSV.
This example defines and uses two custom write converters to strip and upcase generated fields:
strip_converter = proc {|field| field.respond_to?(:strip) ? field.strip : field }
upcase_converter = proc {|field| field.respond_to?(:upcase) ? field.upcase : field }
converters = [strip_converter, upcase_converter]
output_string = CSV.generate(write_converters: converters) do |csv|
csv << [' foo ', 0]
csv << [' bar ', 1]
csv << [' baz ', 2]
end
output_string # => "FOO,0\nBAR,1\nBAZ,2\n"
=== RFC 4180 Compliance
By default, \CSV generates data that is compliant with
{RFC 4180}[https://tools.ietf.org/html/rfc4180]
with respect to:
- Column separator.
- Quote character.
==== Row Separator
RFC 4180 specifies the row separator CRLF (Ruby <tt>"\r\n"</tt>).
===== Recipe: Generate Compliant Row Separator
For strict compliance, use option +:row_sep+ to specify row separator <tt>"\r\n"</tt>:
output_string = CSV.generate('', row_sep: "\r\n") do |csv|
csv << ['Foo', 0]
csv << ['Bar', 1]
csv << ['Baz', 2]
end
output_string # => "Foo,0\r\nBar,1\r\nBaz,2\r\n"
===== Recipe: Generate Non-Compliant Row Separator
For data with non-compliant row separators, use option +:row_sep+ with a different value:
This example source uses semicolon (<tt>";'</tt>) as its row separator:
output_string = CSV.generate('', row_sep: ";") do |csv|
csv << ['Foo', 0]
csv << ['Bar', 1]
csv << ['Baz', 2]
end
output_string # => "Foo,0;Bar,1;Baz,2;"
==== Column Separator
RFC 4180 specifies column separator COMMA (Ruby <tt>","</tt>).
===== Recipe: Generate Compliant Column Separator
Because the \CSV default comma separator is <tt>","</tt>,
you need not specify option +:col_sep+ for compliant data:
output_string = CSV.generate('') do |csv|
csv << ['Foo', 0]
csv << ['Bar', 1]
csv << ['Baz', 2]
end
output_string # => "Foo,0\nBar,1\nBaz,2\n"
===== Recipe: Generate Non-Compliant Column Separator
For data with non-compliant column separators, use option +:col_sep+.
This example source uses TAB (<tt>"\t"</tt>) as its column separator:
output_string = CSV.generate('', col_sep: "\t") do |csv|
csv << ['Foo', 0]
csv << ['Bar', 1]
csv << ['Baz', 2]
end
output_string # => "Foo\t0\nBar\t1\nBaz\t2\n"
==== Quote Character
RFC 4180 specifies quote character DQUOTE (Ruby <tt>"\""</tt>).
===== Recipe: Generate Compliant Quote Character
Because the \CSV default quote character is <tt>"\""</tt>,
you need not specify option +:quote_char+ for compliant data:
output_string = CSV.generate('', force_quotes: true) do |csv|
csv << ['Foo', 0]
csv << ['Bar', 1]
csv << ['Baz', 2]
end
output_string # => "\"Foo\",\"0\"\n\"Bar\",\"1\"\n\"Baz\",\"2\"\n"
===== Recipe: Generate Non-Compliant Quote Character
For data with non-compliant quote characters, use option +:quote_char+.
This example source uses SQUOTE (<tt>"'"</tt>) as its quote character:
output_string = CSV.generate('', quote_char: "'", force_quotes: true) do |csv|
csv << ['Foo', 0]
csv << ['Bar', 1]
csv << ['Baz', 2]
end
output_string # => "'Foo','0'\n'Bar','1'\n'Baz','2'\n"
|
