Bettercsv is an alternative to the native Go csv. It provides several additional features:
- A method for retrieving the headers.
- Allows reading to maps with the headers as keys and the fields as values.
- Allows gracefully handling errors to continue reading on error.
// New Attributes:
SkipLineOnErr bool // Skips line when error occurs, allowing reader to continue
// New Methods:
func (r *Reader) Headers() (headers []string, err error)
func (r *Reader) ReadToMap() (recordMap map[string]string, err error)
func (r *Reader) ReadAllToMaps() (records []map[string]string, err error)
func (r *Reader) ReadAllWithErrors() (records [][]string, errs []error)
func (r *Reader) ReadAllToMapsWithErrors() (records []map[string]string, errs []error)
text.csv
first,last,email
John,Doe,john@doe.com
Jane,Doe,jane@doe.com
Initialize our reader:
csvfile, err := os.Open("text.csv")
reader := bettercsv.NewReader(csvfile)
Calling reader.Headers() will return [first last email]. Note: Calling .Headers() will advance the reader to the second line.
Calling reader.ReadToMap() (after calling .Headers()) will return:
[first:John last:Doe email:john@doe.com]
You can call reader.ReadAllToMaps() to return a slice of map[string]string.
When reading line by line using reader.Read(), if an error occurs, csv will continue reading from the error and you will receive a cascade of errors. For example:
text.csv
first,last,email
John,Doe,john@doe.com
Jane,Doe",jane@doe.com
June,Doe,june@doe.com
Jeff,D"oe",jeff@doe.com
Jim,Doe,jim,doe.com
Joan,Doe,joan@doe.com
Jack,"Do"e",jack@doe.com
Jill,Doe,jill@doe.com
test.go
...
for {
record, err := reader.Read()
if err != nil {
if err == io.EOF {
break
}
fmt.Println(err)
}
fmt.Println(record)
}
...Looping over this with reader.Read() and printing each line will result in:
[first last email]
[John Doe john@doe.com]
line 3, column 8: bare " in non-quoted-field
[]
line 4, column 0: wrong number of fields in line
[ jane@doe.com]
[June Doe june@doe.com]
line 6, column 6: bare " in non-quoted-field
[]
line 7, column 2: bare " in non-quoted-field
[]
line 8, column 0: wrong number of fields in line
[ jeff@doe.com]
line 9, column 0: wrong number of fields in line
[Jim Doe jim doe.com]
[Joan Doe joan@doe.com]
line 11, column 8: extraneous " in field
[]
line 14, column 0: extraneous " in field
[]
With reader.SkipLineOnErr = true.
[first last email]
[John Doe john@doe.com]
line 3, column 22: bare " in non-quoted-field
[]
[June Doe june@doe.com]
line 5, column 23: bare " in non-quoted-field
[]
line 6, column 0: wrong number of fields in line
[Jim Doe jim doe.com]
[Joan Doe joan@doe.com]
line 8, column 23: extraneous " in field
[]
[Jill Doe jill@doe.com]
Notice the line numbers for bettercsv point to their correct lines and Jill Doe was removed completely from the standard csv library.
If you prefer to use the reader.ReadAll() method but still want to skip errors, you can use reader.ReadAllWithErrors() to receive both a slice of slices of records and a slice of all the errors.
values:
[[John Doe john@doe.com]
[June Doe june@doe.com]
[Joan Doe joan@doe.com]
[Jill Doe jill@doe.com]]
errors:
[line 3, column 22: bare \" in non-quoted-field
line 5, column 23: bare " in non-quoted-field
line 6, column 0: wrong number of fields in line
line 8, column 23: extraneous " in field]
You can also combine errors and maps with reader.ReadAllToMapsWithErrors().