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All of your “horrors” seem...correct? Its comma delimited, so anything that is between two commas should be parsed without issue; if it’s a string with a comma

by setr 8y ago

All of your “horrors” seem...correct? Its comma delimited, so anything that is between two commas should be parsed without issue; if it’s a string with a comma in it, and unquoted, you simply have a broken csv file. If its quoted, than anything until the next (unescaped) quote is fine, including commas Unless you’re trying to parse csv files with regexes, none of those should be difficult, or even unexpected, to handls with a PEG parser, or any equivalent device Ofc if you’re accepting ambiguity then its just arbitrary how you handle it, but none of your examples afaict present any ambiguity (I’m assuming strings are either quoted or unquoted, with the former primarily allowing commas/newlines in strings; escaping exists as well; comma delimited columns, newline delimited rows)

codeulike 8y ago
Yes, it would be valid CSV. I suppose my point is that naive attempts to roll-your-own CSV parsers tend to fail on the points I listed. Hopefully Q does not do that.
- Dylan16807 8y ago
  They do? Commas and quotes are the two basic features of CSV, so it seems very strange to forget to implement half.
  - 83457 8y ago
    There is a lot of inconsistency out there. I have seen csv files saved in Excel not be import-able by Access because the latter doesn't handle breaks in fields correctly. I've seen csvs saved from various systems such as sql mngmnt studio grid view and wufoo exports not generate csv correctly. There are many lazy attempts at csv generators out there that just throw breaks between records and commas between fields and call it a day.
    - 83457 8y ago
      And even if they do wrap all fields in double quotes it is very common to forget to escape double quotes in fields, then it depends on the parser as to whether it can determine the proper structure of the record.
  - deleted 8y ago
    [deleted]
em500 8y ago
If you need to read to import CSV from someone else, there are tons of ambiguities. Do you interpret an empty field as an empty string or a NULL? If you've treated a column of unquoted digits as numbers so far, do you parse the first row with a non-number in that column as a NaN, NULL or string? If string, do you reinterpret all the previous column values as strings? Many people are not in the position to just return the file to the client/boss and tell them they have a "broken csv file". (They'll tell you they saved it in Excel and it reads back fine, so the problem must be on your end. E.g.: https://stackoverflow.com/questions/43273976/escaping-quotes-and-delimiters-in-csv-files-with-excel https://stackoverflow.com/questions/43273976/escaping-quotes...)

by setr 8y ago

codeulike 8y ago

Yes, it would be valid CSV. I suppose my point is that naive attempts to roll-your-own CSV parsers tend to fail on the points I listed. Hopefully Q does not do that.

Dylan16807 8y ago
They do? Commas and quotes are the two basic features of CSV, so it seems very strange to forget to implement half.
- 83457 8y ago
  There is a lot of inconsistency out there. I have seen csv files saved in Excel not be import-able by Access because the latter doesn't handle breaks in fields correctly. I've seen csvs saved from various systems such as sql mngmnt studio grid view and wufoo exports not generate csv correctly. There are many lazy attempts at csv generators out there that just throw breaks between records and commas between fields and call it a day.
  - 83457 8y ago
    And even if they do wrap all fields in double quotes it is very common to forget to escape double quotes in fields, then it depends on the parser as to whether it can determine the proper structure of the record.
- deleted 8y ago
  [deleted]

em500 8y ago

If you need to read to import CSV from someone else, there are tons of ambiguities. Do you interpret an empty field as an empty string or a NULL? If you've treated a column of unquoted digits as numbers so far, do you parse the first row with a non-number in that column as a NaN, NULL or string? If string, do you reinterpret all the previous column values as strings? Many people are not in the position to just return the file to the client/boss and tell them they have a "broken csv file". (They'll tell you they saved it in Excel and it reads back fine, so the problem must be on your end. E.g.: https://stackoverflow.com/questions/43273976/escaping-quotes-and-delimiters-in-csv-files-with-excel https://stackoverflow.com/questions/43273976/escaping-quotes...)