Bug #15388: CSV parsing behaviour in > 2.5.0

• Status: Closed
• Assignee: kou (Kouhei Sutou)
• Target version: -
• ruby -v: 2.5.1
• Backport: 2.4: UNKNOWN, 2.5: UNKNOWN

[[e-mail] (Dharshan Bharathuru)]

Hi,

It seems like CSV library in 2.5.0 is not behaving as intended while parsing.

header = ["A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q"]

csv_str = "10.4710|859.5170|9000.0000|Y||0.0000||NRM|0||||N|Y|P|NRM|\r\n11.4710|869.5170|9000.0000|Y||0.0000||NRM|0||||N|Y|P|NRM|\r\n"

CSV.parse(csv_str, col_sep: '|', write_headers: true, headers: header)[0]
# produces junk
# #<CSV::Row "A":"0" "B":nil "C":"NRM" "D":"0" "E":nil "F":nil "G":nil "H":"N" "I":"Y" "J":"P" "K":"NRM" "L":nil "M":nil "N":nil "O":nil "P":nil "Q":nil>

But without write_headers option it produces correct parsing.

CSV.parse(csv_str, col_sep: '|', headers: header)[0]

# #<CSV::Row "A":"10.4710" "B":"859.5170" "C":"9000.0000" "D":"Y" "E":nil "F":"0.0000" "G":nil "H":"NRM" "I":"0" "J":nil "K":nil "L":nil "M":"N" "N":"Y" "O":"P" "P":"NRM" "Q":nil>

[nobu (Nobuyoshi Nakada)]

• Description updated (diff)

Why do you want to write headers when parsing?

[nobu (Nobuyoshi Nakada)]

Maybe an error is expected?

diff --git i/lib/csv.rb w/lib/csv.rb
index dca2a45b6a..e4ad55085c 100644
--- i/lib/csv.rb
+++ w/lib/csv.rb
@@ -687,8 +687,9 @@
   # You pass your +str+ to read from, and an optional +options+ containing
   # anything CSV::new() understands.
   #
-  def self.parse(*args, &block)
-    csv = new(*args)
+  def self.parse(data, write_headers: nil, **options, &block)
+    raise ArgumentError.new("Cannot write headers when parsing") if write_headers
+    csv = new(data, **options)
 
     return csv.each(&block) if block_given?
 
@@ -707,7 +708,8 @@
   #
   # The +options+ parameter can be anything CSV::new() understands.
   #
-  def self.parse_line(line, **options)
+  def self.parse_line(line, write_headers: nil, **options)
+    raise ArgumentError.new("Cannot write headers when parsing") if write_headers
     new(line, options).shift
   end
 
diff --git i/test/csv/test_csv_parsing.rb w/test/csv/test_csv_parsing.rb
index e65bbad92e..7e45a429ef 100755
--- i/test/csv/test_csv_parsing.rb
+++ w/test/csv/test_csv_parsing.rb
@@ -239,6 +239,29 @@
                  CSV.parse("a b  d", col_sep: " "))
   end
 
+  def test_parse_write_headers
+    data = "a,b,c"
+    headers = %w[A B C]
+    Tempfile.create(%w[parsing .csv]) do |f|
+      f.puts data
+      f.close
+      File.open(f.path) {|f|
+        assert_raise(ArgumentError) {
+          CSV.parse(f, write_headers: true, headers: headers)
+        }
+        assert_raise(ArgumentError) {
+          CSV.parse_line(f, write_headers: true, headers: headers)
+        }
+      }
+    end
+    assert_raise(ArgumentError) {
+      CSV.parse(data, write_headers: true, headers: headers)
+    }
+    assert_raise(ArgumentError) {
+      CSV.parse_line(data, write_headers: true, headers: headers)
+    }
+  end
+
   private
 
   def assert_parse_errors_out(*args)

[[e-mail] (Dharshan Bharathuru)]

nobu (Nobuyoshi Nakada) wrote:

Why do you want to write headers when parsing?

I needed a object-key reference in future references instead of index based references.

[nobu (Nobuyoshi Nakada)]

[e-mail] (Dharshan Bharathuru) wrote:

I needed a object-key reference in future references instead of index based references.

It doesn't need to write headers.

[kou (Kouhei Sutou)]

It seems that this has been fixed in csv master.
I've released csv gem 3.0.1. Can you try it?

[kou (Kouhei Sutou)]

• Status changed from Open to Assigned
• Assignee set to kou (Kouhei Sutou)

Arguments validation may be better but we need more works for it. For example, we need to add similar logic to CSV.read for this case.

Anyone who wants to work on argument validation should send pull requests to https://github.com/ruby/csv .

[[e-mail] (Dharshan Bharathuru)]

kou (Kouhei Sutou) wrote:

It seems that this has been fixed in csv master.
I've released csv gem 3.0.1. Can you try it?

Thanks. Working fine with version 3.0.1.

[kou (Kouhei Sutou)]

• Status changed from Assigned to Closed

OK. I'll close this.