add form binding and mapping functionality with tests

binding/binding.go

@@ -0,0 +1,83 @@
+package binding
+
+import (
+	"errors"
+	"net/http"
+	"reflect"
+	"strconv"
+)
+
+type FormBinding struct{}
+
+func (FormBinding) Bind(r *http.Request, obj any) error {
+	if r == nil {
+		return errors.New("request is nil")
+	}
+
+	if err := r.ParseForm(); err != nil {
+		return err
+	}
+
+	if r.Form == nil {
+		return errors.New("form is nil")
+	}
+
+	return mapForm(obj, r.Form)
+}
+
+func mapForm(obj any, form map[string][]string) error {
+	val := reflect.ValueOf(obj)
+	if val.Kind() != reflect.Ptr || val.IsNil() {
+		return errors.New("obj must be a non-nil pointer")
+	}
+	val = val.Elem()
+	if val.Kind() != reflect.Struct {
+		return errors.New("obj must be a pointer to a struct")
+	}
+
+	typ := val.Type()
+	for i := 0; i < val.NumField(); i++ {
+		field := val.Field(i)
+		fieldType := typ.Field(i)
+		formTag := fieldType.Tag.Get("form")
+
+		if formTag == "" {
+			formTag = fieldType.Name
+		}
+
+		if values, ok := form[formTag]; ok && len(values) > 0 {
+			value := values[0]
+			switch field.Kind() {
+			case reflect.String:
+				field.SetString(value)
+			case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+				intValue, err := strconv.ParseInt(value, 10, 64)
+				if err != nil {
+					return err
+				}
+				field.SetInt(intValue)
+			case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+				uintValue, err := strconv.ParseUint(value, 10, 64)
+				if err != nil {
+					return err
+				}
+				field.SetUint(uintValue)
+			case reflect.Float32, reflect.Float64:
+				floatValue, err := strconv.ParseFloat(value, 64)
+				if err != nil {
+					return err
+				}
+				field.SetFloat(floatValue)
+			case reflect.Bool:
+				boolValue, err := strconv.ParseBool(value)
+				if err != nil {
+					return err
+				}
+				field.SetBool(boolValue)
+			default:
+				return errors.New("unsupported field type")
+			}
+		}
+	}
+	return nil
+}

binding/binding_test.go

@@ -0,0 +1,64 @@
+package binding
+
+import (
+	"github.com/stretchr/testify/require"
+	"testing"
+)
+
+func Test_mapForm(t *testing.T) {
+	var someStruct struct {
+		StringType  string  `form:"stringtype"`
+		IntType     int     `form:"inttype"`
+		Int8Type    int8    `form:"int8type"`
+		Int16Type   int16   `form:"int16type"`
+		Int32Type   int32   `form:"int32type"`
+		Int64Type   int64   `form:"int64type"`
+		UintType    uint    `form:"uinttype"`
+		Uint8Type   uint8   `form:"uint8type"`
+		Uint16Type  uint16  `form:"uint16type"`
+		Uint32Type  uint32  `form:"uint32type"`
+		Uint64Type  uint64  `form:"uint64type"`
+		Float32Type float32 `form:"float32type"`
+		Float64Type float64 `form:"float64type"`
+		BoolType    bool    `form:"booltype"`
+	}
+
+	formData := map[string][]string{
+		"stringtype": {"stringType"},
+		"inttype":    {"-2147483647"},
+		"int8type":   {"-127"},
+		"int16type":  {"-32767"},
+		"int32type":  {"-2147483647"},
+		"int64type":  {"-9223372036854775807"},
+		"uinttype":   {"4294967295"},
+		"uint8type":  {"255"},
+		"uint16type": {"65535"},
+		"uint32type": {"4294967295"},
+		"uint64type": {"18446744073709551615"},
+		"float32type": {
+			"3.1415927",
+		},
+		"float64type": {
+			"3.141592653589793",
+		},
+		"booltype": {"true"},
+	}
+
+	err := mapForm(&someStruct, formData)
+	require.NoError(t, err)
+	require.Equal(t, "stringType", someStruct.StringType)
+	require.Equal(t, int(-2147483647), someStruct.IntType)
+	require.Equal(t, int8(-127), someStruct.Int8Type)
+	require.Equal(t, int16(-32767), someStruct.Int16Type)
+	require.Equal(t, int32(-2147483647), someStruct.Int32Type)
+	require.Equal(t, int64(-9223372036854775807), someStruct.Int64Type)
+	require.Equal(t, uint(4294967295), someStruct.UintType)
+	require.Equal(t, uint8(255), someStruct.Uint8Type)
+	require.Equal(t, uint16(65535), someStruct.Uint16Type)
+	require.Equal(t, uint32(4294967295), someStruct.Uint32Type)
+	require.Equal(t, uint64(18446744073709551615), someStruct.Uint64Type)
+	require.Equal(t, float32(3.1415927), someStruct.Float32Type)
+	require.Equal(t, float64(3.141592653589793), someStruct.Float64Type)
+	require.Equal(t, true, someStruct.BoolType)
+	t.Log(someStruct)
+}