Add empty modifier (#39)

Author: jcconnell

README.md

@@ -37,23 +37,24 @@ These functions modify the data in-place.
 
 | Name  | Description  |
 |-------|--------------|
+| camel | Camel Cases the data. |
 | default | Sets the provided default value only if the data is equal to it's default datatype value. |
-| trim | Trims space from the data. |
+| empty | Sets the field equal to the datatype default value. e.g. 0 for int. |
+| lcase | lowercases the data. |
 | 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. |
-| tprefix | Trims a prefix from the value using the provided param value. |
-| tsuffix | Trims a suffix from the value using the provided param value. |
-| lcase | lowercases the data. |
-| ucase | Uppercases the data. |
 | snake | Snake Cases the data. |
-| camel | Camel Cases the data. |
-| title | Title Cases the data. |
-| ucfirst | Upper cases the first character of the data. |
 | strip_alpha | Strips all ascii characters from the data. |
-| strip_num | Strips all ascii numeric characters from the data. |
 | strip_alpha_unicode | Strips all unicode characters from the data. |
+| strip_num | Strips all ascii numeric characters from the data. |
 | strip_num_unicode | Strips all unicode numeric characters from the data. |
 | strip_punctuation | Strips all ascii punctuation from the data. |
+| title | Title Cases the data. |
+| tprefix | Trims a prefix from the value using the provided param value. |
+| trim | Trims space from the data. |
+| tsuffix | Trims a suffix from the value using the provided param value. |
+| ucase | Uppercases the data. |
+| ucfirst | Upper cases the first character of the data. |
 
 
 

modifiers/modifiers.go

@@ -7,24 +7,25 @@ import (
 // New returns a modifier with defaults registered
 func New() *mold.Transformer {
 	mod := mold.New()
-	mod.SetTagName("mod")
-	mod.Register("trim", trimSpace)
+	mod.Register("camel", camelCase)
+	mod.Register("default", defaultValue)
+	mod.Register("empty", empty)
+	mod.Register("lcase", toLower)
 	mod.Register("ltrim", trimLeft)
+	mod.Register("name", nameCase)
 	mod.Register("rtrim", trimRight)
-	mod.Register("tprefix", trimPrefix)
-	mod.Register("tsuffix", trimSuffix)
-	mod.Register("lcase", toLower)
-	mod.Register("ucase", toUpper)
 	mod.Register("snake", snakeCase)
-	mod.Register("title", titleCase)
-	mod.Register("name", nameCase)
-	mod.Register("ucfirst", uppercaseFirstCharacterCase)
+	mod.Register("strip_alpha_unicode", stripAlphaUnicodeCase)
 	mod.Register("strip_alpha", stripAlphaCase)
-	mod.Register("strip_num", stripNumCase)
 	mod.Register("strip_num_unicode", stripNumUnicodeCase)
-	mod.Register("strip_alpha_unicode", stripAlphaUnicodeCase)
+	mod.Register("strip_num", stripNumCase)
 	mod.Register("strip_punctuation", stripPunctuation)
-	mod.Register("camel", camelCase)
-	mod.Register("default", defaultValue)
+	mod.Register("title", titleCase)
+	mod.Register("tprefix", trimPrefix)
+	mod.Register("trim", trimSpace)
+	mod.Register("tsuffix", trimSuffix)
+	mod.Register("ucase", toUpper)
+	mod.Register("ucfirst", uppercaseFirstCharacterCase)
+	mod.SetTagName("mod")
 	return mod
 }

modifiers/multi.go

@@ -13,9 +13,7 @@ var (
 	durationType = reflect.TypeOf(time.Duration(0))
 )
 
-//
 // defaultValue allows setting of a default value IF no value is already present.
-//
 func defaultValue(ctx context.Context, fl mold.FieldLevel) error {
 	if !fl.Field().IsZero() {
 		return nil
@@ -74,3 +72,10 @@ func defaultValue(ctx context.Context, fl mold.FieldLevel) error {
 	}
 	return nil
 }
+
+// empty sets the field to the zero value of the field type
+func empty(ctx context.Context, fl mold.FieldLevel) error {
+	zeroValue := reflect.Zero(fl.Field().Type())
+	fl.Field().Set(zeroValue)
+	return nil
+}

modifiers/multi_test.go

@@ -112,3 +112,78 @@ func TestDefault(t *testing.T) {
 		})
 	}
 }
+
+func TestEmpty(t *testing.T) {
+
+	type State int
+	const FINISHED State = 5
+
+	var state State
+
+	conform := New()
+
+	tests := []struct {
+		name        string
+		field       interface{}
+		tags        string
+		expected    interface{}
+		expectError bool
+	}{
+		{
+			name:     "empty enum",
+			field:    FINISHED,
+			tags:     "empty",
+			expected: state,
+		},
+		{
+			name:     "empty string",
+			field:    "test",
+			tags:     "empty",
+			expected: "",
+		},
+		{
+			name:     "empty int",
+			field:    10,
+			tags:     "empty",
+			expected: 0,
+		},
+		{
+			name:     "empty uint",
+			field:    uint(10),
+			tags:     "empty",
+			expected: uint(0),
+		},
+		{
+			name:     "empty float",
+			field:    float32(10),
+			tags:     "empty",
+			expected: float32(0),
+		},
+		{
+			name:     "empty bool",
+			field:    true,
+			tags:     "empty",
+			expected: false,
+		},
+		{
+			name:     "empty time.Duration",
+			field:    time.Duration(10),
+			tags:     "empty",
+			expected: time.Duration(0),
+		},
+	}
+
+	for _, tc := range tests {
+		tc := tc
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+			err := conform.Field(context.Background(), &tc.field, tc.tags)
+			if tc.expectError {
+				NotEqual(t, err, nil)
+				return
+			}
+			Equal(t, err, nil)
+			Equal(t, tc.field, tc.expected)
+		})
+	}
+}

modifiers/string.go

@@ -3,14 +3,15 @@ package modifiers
 import (
 	"bytes"
 	"context"
-	"golang.org/x/text/cases"
-	"golang.org/x/text/language"
 	"reflect"
 	"regexp"
 	"strings"
 	"unicode"
 	"unicode/utf8"
 
+	"golang.org/x/text/cases"
+	"golang.org/x/text/language"
+
 	"github.com/go-playground/mold/v4"
 	"github.com/segmentio/go-camelcase"
 	"github.com/segmentio/go-snakecase"