Strange CSV result for quoted strings in go encoding/csv

Question

I have this little bit of code that kept me busy the whole weekend.

package main

import (
    "encoding/csv"
    "fmt"
    "log"
    "os"
)

func main() {
    f, err := os.Create("./test.csv")
    if err != nil {
        log.Fatal("Error: %s", err)
    }
    defer f.Close()

    w := csv.NewWriter(f)
    var record []string
    record = append(record, "Unquoted string")
    s := "Cr@zy text with , and \\ and \" etc"
    record = append(record, s)
    fmt.Println(record)
    w.Write(record)

    record = make([]string, 0)
    record = append(record, "Quoted string")
    s = fmt.Sprintf("%q", s)
    record = append(record, s)
    fmt.Println(record)
    w.Write(record)

    w.Flush()
}

When run it prints out:

[Unquoted string Cr@zy text with , and \ and " etc]
[Quoted string "Cr@zy text with , and \\ and \" etc"]

The second, quoted text is exactly what I would wish to see in the CSV, but instead I get this:

Unquoted string,"Cr@zy text with , and \ and "" etc"
Quoted string,"""Cr@zy text with , and \\ and \"" etc"""

Where do those extra quotes come from and how do I avoid them? I have tried a number of things, including using strings.Quote and some such but I can't seem to find a perfect solution. Help, please?

Answer 1

It's part of the standard for storing data as CSV. Double quote characters need to be escaped for parsing reasons.

A (double) quote character in a field must be represented by two (double) quote characters.

From: http://en.wikipedia.org/wiki/Comma-separated_values

You don't really have to worry because the CSV reader un-escapes the double quote.

Example:

package main

import (
    "encoding/csv"
    "fmt"
    "os"
)
func checkError(e error){
    if e != nil {
        panic(e)
    }
}
func writeCSV(){
    fmt.Println("Writing csv")
    f, err := os.Create("./test.csv")
    checkError(err)
    defer f.Close()

    w := csv.NewWriter(f)
    s := "Cr@zy text with , and \\ and \" etc"
    record := []string{ 
      "Unquoted string",
      s,
    }
    fmt.Println(record)
    w.Write(record)

    record = []string{ 
      "Quoted string",
      fmt.Sprintf("%q",s),
    }
    fmt.Println(record)
    w.Write(record)
    w.Flush()
}
func readCSV(){
    fmt.Println("Reading csv")
    file, err := os.Open("./test.csv")
    defer file.Close();
    cr := csv.NewReader(file)
    records, err := cr.ReadAll()
    checkError(err)
    for _, record := range records {
        fmt.Println(record)
    }
}
func main() {
   writeCSV()
   readCSV()
}

Output

Writing csv
[Unquoted string Cr@zy text with , and \ and " etc]
[Quoted string "Cr@zy text with , and \\ and \" etc"]
Reading csv
[Unquoted string Cr@zy text with , and \ and " etc]
[Quoted string "Cr@zy text with , and \\ and \" etc"]

Here's the code for the write function. func (w *Writer) Write(record []string) (err error)

Answer 2

I have csv file with line with double quote string like:

text;//*[@class="price"]/span;text

And csv Reader generate error to read csv file. Helpful was:

reader := csv.NewReader(file)
reader.LazyQuotes = true