Merge pull request #4 from nao1215/nchika/add-len-tag-value

Add "len" tag value

README.md

@@ -95,6 +95,7 @@ You set the validation rules following the "validate:" tag according to the rule
 | lte               | Check whether value is less than or equal to the specified value <br> e.g. `validate:"lte=1"` |
 | min               | Check whether value is greater than or equal to the specified value <br> e.g. `validate:"min=1"` |
 | max               | Check whether value is less than or equal to the specified value <br> e.g. `validate:"max=100"` |
+| len 			    | Check whether the length of the value is equal to the specified value <br> e.g. `validate:"len=10"` |
 
 ## License
 [MIT License](./LICENSE)

csv_test.go

@@ -158,6 +158,41 @@ func TestCSV_Decode(t *testing.T) {
 			t.Errorf("CSV.Decode() mismatch (-got +want):\n%s", diff)
 		}
 	})
+
+	t.Run("validate len: success case", func(t *testing.T) {
+		t.Parallel()
+
+		input := `id,name
+1,abc
+2,あいう
+3,👩‍❤‍💋‍👩🇷🇺😂
+`
+		c, err := NewCSV(bytes.NewBufferString(input))
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		type person struct {
+			ID   int    // no validate
+			Name string `validate:"len=3"`
+		}
+		persons := make([]person, 0)
+
+		errs := c.Decode(&persons)
+		if len(errs) != 0 {
+			t.Errorf("CSV.Decode() got errors: %v", errs)
+		}
+
+		want := []person{
+			{ID: 1, Name: "abc"},
+			{ID: 2, Name: "あいう"},
+			{ID: 3, Name: "👩‍❤‍💋‍👩🇷🇺😂"},
+		}
+
+		if diff := cmp.Diff(persons, want); diff != "" {
+			t.Errorf("CSV.Decode() mismatch (-got +want):\n%s", diff)
+		}
+	})
 }
 
 func Test_ErrCheck(t *testing.T) {
@@ -246,7 +281,6 @@ func Test_ErrCheck(t *testing.T) {
 3,120
 4,120.1
 `
-
 		c, err := NewCSV(bytes.NewBufferString(input))
 		if err != nil {
 			t.Fatal(err)
@@ -273,4 +307,43 @@ func Test_ErrCheck(t *testing.T) {
 			}
 		}
 	})
+
+	t.Run("validate len: error case", func(t *testing.T) {
+		t.Parallel()
+
+		input := `id,name
+1,abcd
+2,あいうえ
+3,👩‍❤‍💋‍👩🇷🇺😂🏯
+`
+		c, err := NewCSV(bytes.NewBufferString(input))
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		type person struct {
+			ID   int    // no validate
+			Name string `validate:"len=3"`
+		}
+		persons := make([]person, 0)
+
+		errs := c.Decode(&persons)
+
+		for i, err := range errs {
+			switch i {
+			case 0:
+				if err.Error() != "line:2 column name: target length is not equal to the threshold value: length threshold=3, value=abcd" {
+					t.Errorf("CSV.Decode() got errors: %v", err)
+				}
+			case 1:
+				if err.Error() != "line:3 column name: target length is not equal to the threshold value: length threshold=3, value=あいうえ" {
+					t.Errorf("CSV.Decode() got errors: %v", err)
+				}
+			case 2:
+				if err.Error() != "line:4 column name: target length is not equal to the threshold value: length threshold=3, value=👩‍❤‍💋‍👩🇷🇺😂🏯" {
+					t.Errorf("CSV.Decode() got errors: %v", err)
+				}
+			}
+		}
+	})
 }

errors.go

@@ -35,4 +35,6 @@ var (
 	ErrMin = errors.New("target is less than the minimum value")
 	// ErrMax is returned when the target is greater than the maximum value.
 	ErrMax = errors.New("target is greater than the maximum value")
+	// ErrLength is returned when the target length is not equal to the value.
+	ErrLength = errors.New("target length is not equal to the threshold value")
 )

go.mod

@@ -5,4 +5,5 @@ go 1.20
 require (
 	github.com/google/go-cmp v0.6.0
 	github.com/motemen/go-testutil v0.0.0-20231019055648-af6add1c10c8
+	github.com/rivo/uniseg v0.4.7
 )

go.sum

@@ -2,3 +2,5 @@ github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
 github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/motemen/go-testutil v0.0.0-20231019055648-af6add1c10c8 h1:bSyU9M98Y4Rrs8X1tYkO8hyHsGw1kWCWyG6FnCQ0l/E=
 github.com/motemen/go-testutil v0.0.0-20231019055648-af6add1c10c8/go.mod h1:fz3ptMGvFb+/JIPQadvSpFND5BuGi7cJka/JgG7njN8=
+github.com/rivo/uniseg v0.4.7 h1:WUdvkW8uEhrYfLC4ZzdpI2ztxP1I582+49Oc5Mq64VQ=
+github.com/rivo/uniseg v0.4.7/go.mod h1:FN3SvrM+Zdj16jyLfmOkMNblXMcoc8DfTHruCPUcx88=

parser.go

@@ -115,6 +115,12 @@ func parseValidateTag(tags string) (validators, error) {
 				return nil, err
 			}
 			validatorList = append(validatorList, newMaxValidator(threshold))
+		case strings.HasPrefix(t, lengthTagValue.String()):
+			threshold, err := parseThreshold(t)
+			if err != nil {
+				return nil, err
+			}
+			validatorList = append(validatorList, newLengthValidator(threshold))
 		}
 	}
 	return validatorList, nil

tag.go

@@ -38,6 +38,8 @@ const (
 	minTagValue tagValue = "min"
 	// maxTagValue is the struct tag name for maximum fields.
 	maxTagValue tagValue = "max"
+	// lengthTagValue is the struct tag name for length fields.
+	lengthTagValue tagValue = "len"
 )
 
 // String returns the string representation of the tag.

validation.go

@@ -3,6 +3,8 @@ package csv
 import (
 	"fmt"
 	"strconv"
+
+	"github.com/rivo/uniseg"
 )
 
 // validator is a struct that contains the validation rules for a column.
@@ -356,3 +358,27 @@ func (m *maxValidator) Do(target any) error {
 	}
 	return nil
 }
+
+// lengthValidator is a struct that contains the validation rules for a length column.
+type lengthValidator struct {
+	threshold float64
+}
+
+// newLengthValidator returns a new lengthValidator.
+func newLengthValidator(threshold float64) *lengthValidator {
+	return &lengthValidator{threshold: threshold}
+}
+
+// Do validates the target length is equal to the threshold.
+func (l *lengthValidator) Do(target any) error {
+	v, ok := target.(string)
+	if !ok {
+		return fmt.Errorf("%w: value=%v", ErrLength, target) //nolint
+	}
+
+	count := uniseg.GraphemeClusterCount(v)
+	if count != int(l.threshold) {
+		return fmt.Errorf("%w: length threshold=%d, value=%s", ErrLength, int(l.threshold), v) //nolint
+	}
+	return nil
+}