I’m having a csv file, and want to read:
- Header names
- Fields types
So, I wrote the below:
package main
import (
"encoding/csv"
"fmt"
"os"
"log"
"reflect"
"strconv"
)
func main() {
filePath := "./file.csv"
headerNames := make(map[int]string)
headerTypes := make(map[int]string)
// Load a csv file.
f, _ := os.Open(filePath)
// Create a new reader.
r := csv.NewReader(f)
// Read first row only
header, err := r.Read()
checkError("Some other error occurred", err)
// Add mapping: Column/property name --> record index
for i, v := range header {
headerNames[i] = v
}
// Read second row
record, err := r.Read()
checkError("Some other error occurred", err)
// Check record fields types
for i, v := range record {
var value interface{}
if value, err = strconv.Atoi(v); err != nil {
if value, err = strconv.ParseFloat(v, 64); err != nil {
if value, err = strconv.ParseBool(v); err != nil {
if value, err = strconv.ParseBool(v); err != nil { // <== How to do this with unknown layout
// Value is a string
headerTypes[i] = "string"
value = v
fmt.Println(reflect.TypeOf(value), reflect.ValueOf(value))
} else {
// Value is a timestamp
headerTypes[i] = "time"
fmt.Println(reflect.TypeOf(value), reflect.ValueOf(value))
}
} else {
// Value is a bool
headerTypes[i] = "bool"
fmt.Println(reflect.TypeOf(value), reflect.ValueOf(value))
}
} else {
// Value is a float
headerTypes[i] = "float"
fmt.Println(reflect.TypeOf(value), reflect.ValueOf(value))
}
} else {
// Value is an int
headerTypes[i] = "int"
fmt.Println(reflect.TypeOf(value), reflect.ValueOf(value))
}
}
for i, _ := range header {
fmt.Printf("Header: %v \tis\t %v\n", headerNames[i], headerTypes[i])
}
}
func checkError(message string, err error) {
// Error Logging
if err != nil {
log.Fatal(message, err)
}
}
And with csv file as:
name,age,developer
"Hasan","46.4","true"
I got an output as:
Header: name is string
Header: age is float
Header: developer is bool
The output is correct.
The thing that I could not do is the one is checking if the field is string as I do not know what layout the field could be.
I aware I can pasre string to time as per the format stated at https://go.dev/src/time/format.go, and can build a custom parser, something like:
test, err := fmtdate.Parse("MM/DD/YYYY", "10/15/1983")
if err != nil {
panic(err)
}
But this will work only (as per my knowledge) if I know the layout?
So, again my question is, how can I parse time, or what shall I do to be able to parse it, if I do not know the layout?