handling_unexpected_fields_1_2.go

package main

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

// CSVRecord1 contains a successfully parsed row of the CSV file.
type CSVRecord struct {
	SepalLength  float64
	SepalWidth   float64
	PetalLength  float64
	PetalWidth   float64
	Species      string
	ParseError   error
}

func main() {


	// Open the iris dataset file.
	f, err := os.Open("iris.csv")
	if err != nil {
		log.Fatal(err)
	}
	defer f.Close()

	// Create a new CSV reader reading from the opened file.
	reader := csv.NewReader(f)

	// We should have 5 fields per line. By setting
	// FieldsPerRecord to 5, we can validate that each of the
	// rows in our CSV has the correct number of fields.
	reader.FieldsPerRecord = 5

	// Create a slice value that will hold all of the successfully parsed
	// records from the CSV.
	var csvData []CSVRecord

	// Read in the records looking for unexpected types.
	for {

		// Read in a row. Check if we are at the end of the file.
		record, err := reader.Read()
		if err == io.EOF {
			break
		}

		// If we had a parsing error, log the error and move on.
		if err != nil {
			log.Println(err)
			continue
		}

		// Create a CSVRecord1 value for the row.
		var csvRecord CSVRecord

		// Parse each of the values in the record based on an expected type.
		for idx, value := range record {

			// Parse the value in the record as a string for the string column.
			if idx == 4 {

				// Validate that the value is not an empty string. If the
				// value is an empty string break the parsing loop.
				if value == "" {
					log.Printf("Unexpected type in column %d\n", idx)
					csvRecord.ParseError = fmt.Errorf("Empty string value")
					break
				}

				// Add the string value to the CSVRecord1.
				csvRecord.Species = value
				continue
			}

			// Otherwise, parse the value in the record as a float64.
			var floatValue float64

			// If the value can not be parsed as a float, log and break the
			// parsing loop.
			if floatValue, err = strconv.ParseFloat(value, 64); err != nil {
				log.Printf("Unexpected type in column %d\n", idx)
				csvRecord.ParseError = fmt.Errorf("Could not parse float")
				break
			}

			// Add the float value to the respective field in the CSVRecord1.
			switch idx {
			case 0:
				csvRecord.SepalLength = floatValue
			case 1:
				csvRecord.SepalWidth = floatValue
			case 2:
				csvRecord.PetalLength = floatValue
			case 3:
				csvRecord.PetalWidth = floatValue
			}
		}

		// Append successfully parsed records to the slice defined above.
		if csvRecord.ParseError == nil {
			csvData = append(csvData, csvRecord)
		}
	}

}