Add a new slug modifier (#42)

README.md

@@ -44,6 +44,7 @@ These functions modify the data in-place.
 | ltrim               | Trims spaces from the left of the data provided in the params.                            |
 | rtrim               | Trims spaces from the right of the data provided in the params.                           |
 | set                 | Set the provided value.                                                                   |
+| slug                | Converts the field to a [slug](https://github.com/gosimple/slug)                          |
 | snake               | Snake Cases the data.                                                                     |
 | strip_alpha         | Strips all ascii characters from the data.                                                |
 | strip_alpha_unicode | Strips all unicode characters from the data.                                              |

go.mod

@@ -12,6 +12,8 @@ require (
 
 require (
 	github.com/davecgh/go-spew v1.1.0 // indirect
+	github.com/gosimple/slug v1.13.1 // indirect
+	github.com/gosimple/unidecode v1.0.1 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c // indirect
 )

go.sum

@@ -2,6 +2,10 @@ github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/go-playground/assert/v2 v2.0.1 h1:MsBgLAaY856+nPRTKrp3/OZK38U/wa0CcBYNjji3q3A=
 github.com/go-playground/assert/v2 v2.0.1/go.mod h1:VDjEfimB/XKnb+ZQfWdccd7VUvScMdVu0Titje2rxJ4=
+github.com/gosimple/slug v1.13.1 h1:bQ+kpX9Qa6tHRaK+fZR0A0M2Kd7Pa5eHPPsb1JpHD+Q=
+github.com/gosimple/slug v1.13.1/go.mod h1:UiRaFH+GEilHstLUmcBgWcI42viBN7mAb818JrYOeFQ=
+github.com/gosimple/unidecode v1.0.1 h1:hZzFTMMqSswvf0LBJZCZgThIZrpDHFXux9KeGmn6T/o=
+github.com/gosimple/unidecode v1.0.1/go.mod h1:CP0Cr1Y1kogOtx0bJblKzsVWrqYaqfNOnHzpgWw4Awc=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/segmentio/go-camelcase v0.0.0-20160726192923-7085f1e3c734 h1:Cpx2WLIv6fuPvaJAHNhYOgYzk/8RcJXu/8+mOrxf2KM=

modifiers/modifiers.go

@@ -16,6 +16,7 @@ func New() *mold.Transformer {
 	mod.Register("rtrim", trimRight)
 	mod.Register("set", setValue)
 	mod.Register("snake", snakeCase)
+	mod.Register("slug", slugCase)
 	mod.Register("strip_alpha_unicode", stripAlphaUnicodeCase)
 	mod.Register("strip_alpha", stripAlphaCase)
 	mod.Register("strip_num_unicode", stripNumUnicodeCase)

modifiers/string.go

@@ -13,6 +13,7 @@ import (
 	"golang.org/x/text/language"
 
 	"github.com/go-playground/mold/v4"
+	"github.com/gosimple/slug"
 	"github.com/segmentio/go-camelcase"
 	"github.com/segmentio/go-snakecase"
 )
@@ -89,6 +90,15 @@ func snakeCase(ctx context.Context, fl mold.FieldLevel) error {
 	return nil
 }
 
+// slug converts string to a slug
+func slugCase(ctx context.Context, fl mold.FieldLevel) error {
+	switch fl.Field().Kind() {
+	case reflect.String:
+		fl.Field().SetString(slug.Make(fl.Field().String()))
+	}
+	return nil
+}
+
 // titleCase converts string to title case, e.g. "this is a sentence" -> "This Is A Sentence"
 func titleCase(ctx context.Context, fl mold.FieldLevel) error {
 	switch fl.Field().Kind() {

modifiers/string_test.go

@@ -458,6 +458,52 @@ func TestTitleCase(t *testing.T) {
 	}
 }
 
+func TestSlugCase(t *testing.T) {
+	conform := New()
+
+	s := "this-is +a SentencE9"
+	expected := "this-is-a-sentence9"
+
+	type Test struct {
+		String string `mod:"slug"`
+	}
+
+	tt := Test{String: s}
+	err := conform.Struct(context.Background(), &tt)
+	if err != nil {
+		log.Fatal(err)
+	}
+	if tt.String != expected {
+		t.Fatalf("Unexpected value '%s'\n", tt.String)
+	}
+
+	err = conform.Field(context.Background(), &s, "slug")
+	if err != nil {
+		log.Fatal(err)
+	}
+	if s != expected {
+		t.Fatalf("Unexpected value '%s'\n", s)
+	}
+
+	var iface interface{}
+	err = conform.Field(context.Background(), &iface, "slug")
+	if err != nil {
+		log.Fatal(err)
+	}
+	if iface != nil {
+		t.Fatalf("Unexpected value '%v'\n", nil)
+	}
+
+	iface = s
+	err = conform.Field(context.Background(), &iface, "slug")
+	if err != nil {
+		log.Fatal(err)
+	}
+	if iface != expected {
+		t.Fatalf("Unexpected value '%v'\n", iface)
+	}
+}
+
 func TestNameCase(t *testing.T) {
 	conform := New()