Feature/error management

07-behaviour_error_handling/internal/beer.go

@@ -2,6 +2,8 @@ package beerscli
 
 import (
 	"encoding/json"
+
+	"github.com/CodelyTV/golang-examples/07-behaviour_error_handling/internal/errors"
 )
 
 // Beer representation of beer into data struct
@@ -65,9 +67,11 @@ var toID = map[string]BeerType{
 func (t *BeerType) UnmarshalJSON(b []byte) error {
 	var j string
 	err := json.Unmarshal(b, &j)
+
 	if err != nil {
-		return err
+		return errors.WrapConversionError(err, "Could not convert retrieved bytes to JSON")
 	}
+
 	*t = toID[j]
 	return nil
 }

07-behaviour_error_handling/internal/cli/beers.go

@@ -36,10 +36,20 @@ func runBeersFn(repository beerscli.BeerRepo) CobraFn {
 			log.Fatal(err)
 		}
 
+		if errors.IsFileHandlingError(err) {
+			log.Fatal(err)
+		}
+
 		id, _ := cmd.Flags().GetString(idFlag)
 
 		if id != "" {
-			i, _ := strconv.Atoi(id)
+			var i int
+			i, err = strconv.Atoi(id)
+
+			if errors.IsConversionError(err) {
+				log.Fatal(err)
+			}
+
 			for _, beer := range beers {
 				if beer.ProductID == i {
 					fmt.Println(beer)

07-behaviour_error_handling/internal/errors/conversionerror.go

@@ -0,0 +1,28 @@
+package errors
+
+import (
+	"github.com/pkg/errors"
+)
+
+type conversionError struct {
+	error
+}
+
+// WrapConversionError returns an error which wraps err that satisfies
+// IsConversionError()
+func WrapConversionError(err error, format string, args ...interface{}) error {
+	return &conversionError{errors.Wrapf(err, format, args...)}
+}
+
+// NewConversionError returns an error which satisfies IsConversionError()
+func NewConversionError(format string, args ...interface{}) error {
+	return &conversionError{errors.Errorf(format, args...)}
+}
+
+// IsConversionError reports whether err was created with ConversionError() or
+// NewConversionError()
+func IsConversionError(err error) bool {
+	err = errors.Cause(err)
+	_, ok := err.(*conversionError)
+	return ok
+}

07-behaviour_error_handling/internal/errors/filehandlingerror.go

@@ -0,0 +1,28 @@
+package errors
+
+import (
+	"github.com/pkg/errors"
+)
+
+type fileHandlingError struct {
+	error
+}
+
+// WrapFileHandlingError returns an error which wraps err that satisfies
+// IsFileHandlingError()
+func WrapFileHandlingError(err error, format string, args ...interface{}) error {
+	return &fileHandlingError{errors.Wrapf(err, format, args...)}
+}
+
+// NewFileHandlingError returns an error which satisfies IsFileHandlingError()
+func NewFileHandlingError(format string, args ...interface{}) error {
+	return &fileHandlingError{errors.Errorf(format, args...)}
+}
+
+// IsFileHandlingError reports whether err was created with FileHandlingError() or
+// NewFileHandlingError()
+func IsFileHandlingError(err error) bool {
+	err = errors.Cause(err)
+	_, ok := err.(*fileHandlingError)
+	return ok
+}

07-behaviour_error_handling/internal/storage/csv/repository.go

@@ -7,6 +7,7 @@ import (
 	"strings"
 
 	beerscli "github.com/CodelyTV/golang-examples/07-behaviour_error_handling/internal"
+	"github.com/CodelyTV/golang-examples/07-behaviour_error_handling/internal/errors"
 )
 
 type repository struct {
@@ -19,15 +20,31 @@ func NewRepository() beerscli.BeerRepo {
 
 // GetBeers fetch beers data from csv
 func (r *repository) GetBeers() ([]beerscli.Beer, error) {
-	f, _ := os.Open("07-behaviour_error_handling/data/beers.csv")
+	const filePath = "07-behaviour_error_handling/data/beers.csv"
+	f, err := os.Open(filePath)
+
+	if err != nil {
+		return nil, errors.WrapFileHandlingError(err, "error opening file %s", filePath)
+	}
+
 	reader := bufio.NewReader(f)
 
 	var beers []beerscli.Beer
 
-	for line := readLine(reader); line != nil; line = readLine(reader) {
+	var line []byte
+
+	for line, err = readLine(reader); line != nil; line, err = readLine(reader) {
+		if err != nil {
+			return nil, err
+		}
 		values := strings.Split(string(line), ",")
 
-		productID, _ := strconv.Atoi(values[0])
+		var productID int
+		productID, err = strconv.Atoi(values[0])
+
+		if err != nil {
+			return nil, errors.WrapConversionError(err, "error while converting 'productId' from ascii to integer: %s", values[0])
+		}
 
 		beer := beerscli.NewBeer(
 			productID,
@@ -45,7 +62,11 @@ func (r *repository) GetBeers() ([]beerscli.Beer, error) {
 	return beers, nil
 }
 
-func readLine(reader *bufio.Reader) (line []byte) {
-	line, _, _ = reader.ReadLine()
+func readLine(reader *bufio.Reader) (line []byte, err error) {
+	line, _, err = reader.ReadLine()
+
+	if err != nil {
+		return nil, errors.WrapFileHandlingError(err, "could not read next line of buffer")
+	}
 	return
 }