feat: add httpc.Do & httpc.Service.Do (#1775)

* backup

* backup

* backup

* feat: add httpc.Do & httpc.Service.Do

* fix: not using strings.Cut, it's from Go 1.18

* chore: remove redudant code

* feat: httpc.Do finished

* chore: fix reviewdog

* chore: break loop if found

* add more tests

core/mapping/marshaler.go

@@ -0,0 +1,176 @@
+package mapping
+
+import (
+	"fmt"
+	"reflect"
+	"strings"
+)
+
+const (
+	emptyTag       = ""
+	tagKVSeparator = ":"
+)
+
+// Marshal marshals the given val and returns the map that contains the fields.
+// optional=another is not implemented, and it's hard to implement and not common used.
+func Marshal(val interface{}) (map[string]map[string]interface{}, error) {
+	ret := make(map[string]map[string]interface{})
+	tp := reflect.TypeOf(val)
+	rv := reflect.ValueOf(val)
+
+	for i := 0; i < tp.NumField(); i++ {
+		field := tp.Field(i)
+		value := rv.Field(i)
+		if err := processMember(field, value, ret); err != nil {
+			return nil, err
+		}
+	}
+
+	return ret, nil
+}
+
+func getTag(field reflect.StructField) (string, bool) {
+	tag := string(field.Tag)
+	if i := strings.Index(tag, tagKVSeparator); i >= 0 {
+		return strings.TrimSpace(tag[:i]), true
+	}
+
+	return strings.TrimSpace(tag), false
+}
+
+func processMember(field reflect.StructField, value reflect.Value,
+	collector map[string]map[string]interface{}) error {
+	var key string
+	var opt *fieldOptions
+	var err error
+	tag, ok := getTag(field)
+	if !ok {
+		tag = emptyTag
+		key = field.Name
+	} else {
+		key, opt, err = parseKeyAndOptions(tag, field)
+		if err != nil {
+			return err
+		}
+
+		if err = validate(field, value, opt); err != nil {
+			return err
+		}
+	}
+
+	val := value.Interface()
+	if opt != nil && opt.FromString {
+		val = fmt.Sprint(val)
+	}
+
+	m, ok := collector[tag]
+	if ok {
+		m[key] = val
+	} else {
+		m = map[string]interface{}{
+			key: val,
+		}
+	}
+	collector[tag] = m
+
+	return nil
+}
+
+func validate(field reflect.StructField, value reflect.Value, opt *fieldOptions) error {
+	if opt == nil || !opt.Optional {
+		if err := validateOptional(field, value); err != nil {
+			return err
+		}
+	}
+
+	if opt == nil {
+		return nil
+	}
+
+	if len(opt.Options) > 0 {
+		if err := validateOptions(value, opt); err != nil {
+			return err
+		}
+	}
+
+	if opt.Range != nil {
+		if err := validateRange(value, opt); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func validateOptional(field reflect.StructField, value reflect.Value) error {
+	switch field.Type.Kind() {
+	case reflect.Ptr:
+		if value.IsNil() {
+			return fmt.Errorf("field %q is nil", field.Name)
+		}
+	case reflect.Array, reflect.Slice, reflect.Map:
+		if value.IsNil() || value.Len() == 0 {
+			return fmt.Errorf("field %q is empty", field.Name)
+		}
+	}
+
+	return nil
+}
+
+func validateOptions(value reflect.Value, opt *fieldOptions) error {
+	var found bool
+	val := fmt.Sprint(value.Interface())
+	for i := range opt.Options {
+		if opt.Options[i] == val {
+			found = true
+			break
+		}
+	}
+	if !found {
+		return fmt.Errorf("field %q not in options", val)
+	}
+
+	return nil
+}
+
+func validateRange(value reflect.Value, opt *fieldOptions) error {
+	var val float64
+	switch v := value.Interface().(type) {
+	case int:
+		val = float64(v)
+	case int8:
+		val = float64(v)
+	case int16:
+		val = float64(v)
+	case int32:
+		val = float64(v)
+	case int64:
+		val = float64(v)
+	case uint:
+		val = float64(v)
+	case uint8:
+		val = float64(v)
+	case uint16:
+		val = float64(v)
+	case uint32:
+		val = float64(v)
+	case uint64:
+		val = float64(v)
+	case float32:
+		val = float64(v)
+	case float64:
+		val = v
+	default:
+		return fmt.Errorf("unknown support type for range %q", value.Type().String())
+	}
+
+	// validates [left, right], [left, right), (left, right], (left, right)
+	if val < opt.Range.left ||
+		(!opt.Range.leftInclude && val == opt.Range.left) ||
+		val > opt.Range.right ||
+		(!opt.Range.rightInclude && val == opt.Range.right) {
+		return fmt.Errorf("%v out of range", value.Interface())
+	}
+
+	return nil
+}

core/mapping/marshaler_test.go

@@ -0,0 +1,233 @@
+package mapping
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestMarshal(t *testing.T) {
+	v := struct {
+		Name      string `path:"name"`
+		Address   string `json:"address,options=[beijing,shanghai]"`
+		Age       int    `json:"age"`
+		Anonymous bool
+	}{
+		Name:      "kevin",
+		Address:   "shanghai",
+		Age:       20,
+		Anonymous: true,
+	}
+
+	m, err := Marshal(v)
+	assert.Nil(t, err)
+	assert.Equal(t, "kevin", m["path"]["name"])
+	assert.Equal(t, "shanghai", m["json"]["address"])
+	assert.Equal(t, 20, m["json"]["age"].(int))
+	assert.True(t, m[emptyTag]["Anonymous"].(bool))
+}
+
+func TestMarshal_OptionalPtr(t *testing.T) {
+	var val = 1
+	v := struct {
+		Age *int `json:"age"`
+	}{
+		Age: &val,
+	}
+
+	m, err := Marshal(v)
+	assert.Nil(t, err)
+	assert.Equal(t, 1, *m["json"]["age"].(*int))
+}
+
+func TestMarshal_OptionalPtrNil(t *testing.T) {
+	v := struct {
+		Age *int `json:"age"`
+	}{}
+
+	_, err := Marshal(v)
+	assert.NotNil(t, err)
+}
+
+func TestMarshal_BadOptions(t *testing.T) {
+	v := struct {
+		Name string `json:"name,options"`
+	}{
+		Name: "kevin",
+	}
+
+	_, err := Marshal(v)
+	assert.NotNil(t, err)
+}
+
+func TestMarshal_NotInOptions(t *testing.T) {
+	v := struct {
+		Name string `json:"name,options=[a,b]"`
+	}{
+		Name: "kevin",
+	}
+
+	_, err := Marshal(v)
+	assert.NotNil(t, err)
+}
+
+func TestMarshal_Nested(t *testing.T) {
+	type address struct {
+		Country string `json:"country"`
+		City    string `json:"city"`
+	}
+	v := struct {
+		Name    string  `json:"name,options=[kevin,wan]"`
+		Address address `json:"address"`
+	}{
+		Name: "kevin",
+		Address: address{
+			Country: "China",
+			City:    "Shanghai",
+		},
+	}
+
+	m, err := Marshal(v)
+	assert.Nil(t, err)
+	assert.Equal(t, "kevin", m["json"]["name"])
+	assert.Equal(t, "China", m["json"]["address"].(address).Country)
+	assert.Equal(t, "Shanghai", m["json"]["address"].(address).City)
+}
+
+func TestMarshal_NestedPtr(t *testing.T) {
+	type address struct {
+		Country string `json:"country"`
+		City    string `json:"city"`
+	}
+	v := struct {
+		Name    string   `json:"name,options=[kevin,wan]"`
+		Address *address `json:"address"`
+	}{
+		Name: "kevin",
+		Address: &address{
+			Country: "China",
+			City:    "Shanghai",
+		},
+	}
+
+	m, err := Marshal(v)
+	assert.Nil(t, err)
+	assert.Equal(t, "kevin", m["json"]["name"])
+	assert.Equal(t, "China", m["json"]["address"].(*address).Country)
+	assert.Equal(t, "Shanghai", m["json"]["address"].(*address).City)
+}
+
+func TestMarshal_Slice(t *testing.T) {
+	v := struct {
+		Name []string `json:"name"`
+	}{
+		Name: []string{"kevin", "wan"},
+	}
+
+	m, err := Marshal(v)
+	assert.Nil(t, err)
+	assert.ElementsMatch(t, []string{"kevin", "wan"}, m["json"]["name"].([]string))
+}
+
+func TestMarshal_SliceNil(t *testing.T) {
+	v := struct {
+		Name []string `json:"name"`
+	}{
+		Name: nil,
+	}
+
+	_, err := Marshal(v)
+	assert.NotNil(t, err)
+}
+
+func TestMarshal_Range(t *testing.T) {
+	v := struct {
+		Int     int     `json:"int,range=[1:3]"`
+		Int8    int8    `json:"int8,range=[1:3)"`
+		Int16   int16   `json:"int16,range=(1:3]"`
+		Int32   int32   `json:"int32,range=(1:3)"`
+		Int64   int64   `json:"int64,range=(1:3)"`
+		Uint    uint    `json:"uint,range=[1:3]"`
+		Uint8   uint8   `json:"uint8,range=[1:3)"`
+		Uint16  uint16  `json:"uint16,range=(1:3]"`
+		Uint32  uint32  `json:"uint32,range=(1:3)"`
+		Uint64  uint64  `json:"uint64,range=(1:3)"`
+		Float32 float32 `json:"float32,range=(1:3)"`
+		Float64 float64 `json:"float64,range=(1:3)"`
+	}{
+		Int:     1,
+		Int8:    1,
+		Int16:   2,
+		Int32:   2,
+		Int64:   2,
+		Uint:    1,
+		Uint8:   1,
+		Uint16:  2,
+		Uint32:  2,
+		Uint64:  2,
+		Float32: 2,
+		Float64: 2,
+	}
+
+	m, err := Marshal(v)
+	assert.Nil(t, err)
+	assert.Equal(t, 1, m["json"]["int"].(int))
+	assert.Equal(t, int8(1), m["json"]["int8"].(int8))
+	assert.Equal(t, int16(2), m["json"]["int16"].(int16))
+	assert.Equal(t, int32(2), m["json"]["int32"].(int32))
+	assert.Equal(t, int64(2), m["json"]["int64"].(int64))
+	assert.Equal(t, uint(1), m["json"]["uint"].(uint))
+	assert.Equal(t, uint8(1), m["json"]["uint8"].(uint8))
+	assert.Equal(t, uint16(2), m["json"]["uint16"].(uint16))
+	assert.Equal(t, uint32(2), m["json"]["uint32"].(uint32))
+	assert.Equal(t, uint64(2), m["json"]["uint64"].(uint64))
+	assert.Equal(t, float32(2), m["json"]["float32"].(float32))
+	assert.Equal(t, float64(2), m["json"]["float64"].(float64))
+}
+
+func TestMarshal_RangeOut(t *testing.T) {
+	tests := []interface{}{
+		struct {
+			Int int `json:"int,range=[1:3]"`
+		}{
+			Int: 4,
+		},
+		struct {
+			Int int `json:"int,range=(1:3]"`
+		}{
+			Int: 1,
+		},
+		struct {
+			Int int `json:"int,range=[1:3)"`
+		}{
+			Int: 3,
+		},
+		struct {
+			Int int `json:"int,range=(1:3)"`
+		}{
+			Int: 3,
+		},
+		struct {
+			Bool bool `json:"bool,range=(1:3)"`
+		}{
+			Bool: true,
+		},
+	}
+
+	for _, test := range tests {
+		_, err := Marshal(test)
+		assert.NotNil(t, err)
+	}
+}
+
+func TestMarshal_FromString(t *testing.T) {
+	v := struct {
+		Age int `json:"age,string"`
+	}{
+		Age: 10,
+	}
+
+	m, err := Marshal(v)
+	assert.Nil(t, err)
+	assert.Equal(t, "10", m["json"]["age"].(string))
+}

core/mapping/unmarshaler.go

@@ -97,10 +97,6 @@ func (u *Unmarshaler) unmarshalWithFullName(m Valuer, v interface{}, fullName st
 	numFields := rte.NumField()
 	for i := 0; i < numFields; i++ {
 		field := rte.Field(i)
-		if usingDifferentKeys(u.key, field) {
-			continue
-		}
-
 		if err := u.processField(field, rve.Field(i), m, fullName); err != nil {
 			return err
 		}

rest/httpc/requests.go

@@ -1,8 +1,17 @@
 package httpc
 
 import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
 	"net/http"
+	nurl "net/url"
+	"strings"
 
+	"github.com/zeromicro/go-zero/core/lang"
+	"github.com/zeromicro/go-zero/core/mapping"
 	"github.com/zeromicro/go-zero/rest/httpc/internal"
 )
 
@@ -10,6 +19,17 @@ var interceptors = []internal.Interceptor{
 	internal.LogInterceptor,
 }
 
+// Do sends an HTTP request with the given arguments and returns an HTTP response.
+// data is automatically marshal into a *httpRequest, typically it's defined in an API file.
+func Do(ctx context.Context, method, url string, data interface{}) (*http.Response, error) {
+	req, err := buildRequest(ctx, method, url, data)
+	if err != nil {
+		return nil, err
+	}
+
+	return DoRequest(req)
+}
+
 // DoRequest sends an HTTP request and returns an HTTP response.
 func DoRequest(r *http.Request) (*http.Response, error) {
 	return request(r, defaultClient{})
@@ -27,6 +47,107 @@ func (c defaultClient) do(r *http.Request) (*http.Response, error) {
 	return http.DefaultClient.Do(r)
 }
 
+func buildFormQuery(u *nurl.URL, val map[string]interface{}) string {
+	query := u.Query()
+	for k, v := range val {
+		query.Add(k, fmt.Sprint(v))
+	}
+
+	return query.Encode()
+}
+
+func buildRequest(ctx context.Context, method, url string, data interface{}) (*http.Request, error) {
+	u, err := nurl.Parse(url)
+	if err != nil {
+		return nil, err
+	}
+
+	var val map[string]map[string]interface{}
+	if data != nil {
+		val, err = mapping.Marshal(data)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	if err := fillPath(u, val[pathKey]); err != nil {
+		return nil, err
+	}
+
+	var reader io.Reader
+	jsonVars, hasJsonBody := val[jsonKey]
+	if hasJsonBody {
+		if method == http.MethodGet {
+			return nil, ErrGetWithBody
+		}
+
+		var buf bytes.Buffer
+		enc := json.NewEncoder(&buf)
+		if err := enc.Encode(jsonVars); err != nil {
+			return nil, err
+		}
+
+		reader = &buf
+	}
+
+	req, err := http.NewRequestWithContext(ctx, method, u.String(), reader)
+	if err != nil {
+		return nil, err
+	}
+
+	req.URL.RawQuery = buildFormQuery(u, val[formKey])
+	fillHeader(req, val[headerKey])
+	if hasJsonBody {
+		req.Header.Set(contentType, applicationJson)
+	}
+
+	return req, nil
+}
+
+func fillHeader(r *http.Request, val map[string]interface{}) {
+	for k, v := range val {
+		r.Header.Add(k, fmt.Sprint(v))
+	}
+}
+
+func fillPath(u *nurl.URL, val map[string]interface{}) error {
+	used := make(map[string]lang.PlaceholderType)
+	fields := strings.Split(u.Path, slash)
+
+	for i := range fields {
+		field := fields[i]
+		if len(field) > 0 && field[0] == colon {
+			name := field[1:]
+			ival, ok := val[name]
+			if !ok {
+				return fmt.Errorf("missing path variable %q", name)
+			}
+			value := fmt.Sprint(ival)
+			if len(value) == 0 {
+				return fmt.Errorf("empty path variable %q", name)
+			}
+			fields[i] = value
+			used[name] = lang.Placeholder
+		}
+	}
+
+	if len(val) != len(used) {
+		for key := range used {
+			delete(val, key)
+		}
+
+		var unused []string
+		for key := range val {
+			unused = append(unused, key)
+		}
+
+		return fmt.Errorf("more path variables are provided: %q", strings.Join(unused, ", "))
+	}
+
+	u.Path = strings.Join(fields, slash)
+	return nil
+}
+
 func request(r *http.Request, cli client) (*http.Response, error) {
 	var respHandlers []internal.ResponseHandler
 	for _, interceptor := range interceptors {

rest/httpc/requests_test.go

@@ -1,14 +1,17 @@
 package httpc
 
 import (
+	"context"
 	"net/http"
 	"net/http/httptest"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
+	"github.com/zeromicro/go-zero/rest/httpx"
+	"github.com/zeromicro/go-zero/rest/router"
 )
 
-func TestDo(t *testing.T) {
+func TestDoRequest(t *testing.T) {
 	svr := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 	}))
 	defer svr.Close()
@@ -19,7 +22,7 @@ func TestDo(t *testing.T) {
 	assert.Equal(t, http.StatusOK, resp.StatusCode)
 }
 
-func TestDoNotFound(t *testing.T) {
+func TestDoRequest_NotFound(t *testing.T) {
 	svr := httptest.NewServer(http.NotFoundHandler())
 	defer svr.Close()
 	req, err := http.NewRequest(http.MethodPost, svr.URL, nil)
@@ -30,7 +33,7 @@ func TestDoNotFound(t *testing.T) {
 	assert.Equal(t, http.StatusNotFound, resp.StatusCode)
 }
 
-func TestDoMoved(t *testing.T) {
+func TestDoRequest_Moved(t *testing.T) {
 	svr := httptest.NewServer(http.RedirectHandler("/foo", http.StatusMovedPermanently))
 	defer svr.Close()
 	req, err := http.NewRequest(http.MethodGet, svr.URL, nil)
@@ -39,3 +42,84 @@ func TestDoMoved(t *testing.T) {
 	// too many redirects
 	assert.NotNil(t, err)
 }
+
+func TestDo(t *testing.T) {
+	type Data struct {
+		Key    string `path:"key"`
+		Value  int    `form:"value"`
+		Header string `header:"X-Header"`
+		Body   string `json:"body"`
+	}
+
+	rt := router.NewRouter()
+	err := rt.Handle(http.MethodPost, "/nodes/:key",
+		http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			var req Data
+			assert.Nil(t, httpx.Parse(r, &req))
+		}))
+	assert.Nil(t, err)
+
+	svr := httptest.NewServer(http.HandlerFunc(rt.ServeHTTP))
+	defer svr.Close()
+
+	data := Data{
+		Key:    "foo",
+		Value:  10,
+		Header: "my-header",
+		Body:   "my body",
+	}
+	resp, err := Do(context.Background(), http.MethodPost, svr.URL+"/nodes/:key", data)
+	assert.Nil(t, err)
+	assert.Equal(t, http.StatusOK, resp.StatusCode)
+}
+
+func TestDo_BadRequest(t *testing.T) {
+	_, err := Do(context.Background(), http.MethodPost, ":/nodes/:key", nil)
+	assert.NotNil(t, err)
+
+	val1 := struct {
+		Value string `json:"value,options=[a,b]"`
+	}{
+		Value: "c",
+	}
+	_, err = Do(context.Background(), http.MethodPost, "/nodes/:key", val1)
+	assert.NotNil(t, err)
+
+	val2 := struct {
+		Value string `path:"val"`
+	}{
+		Value: "",
+	}
+	_, err = Do(context.Background(), http.MethodPost, "/nodes/:key", val2)
+	assert.NotNil(t, err)
+
+	val3 := struct {
+		Value string `path:"key"`
+		Body  string `json:"body"`
+	}{
+		Value: "foo",
+	}
+	_, err = Do(context.Background(), http.MethodGet, "/nodes/:key", val3)
+	assert.NotNil(t, err)
+
+	_, err = Do(context.Background(), "\n", "rtmp://nodes", nil)
+	assert.NotNil(t, err)
+
+	val4 := struct {
+		Value string `path:"val"`
+	}{
+		Value: "",
+	}
+	_, err = Do(context.Background(), http.MethodPost, "/nodes/:val", val4)
+	assert.NotNil(t, err)
+
+	val5 := struct {
+		Value   string `path:"val"`
+		Another int    `path:"foo"`
+	}{
+		Value:   "1",
+		Another: 2,
+	}
+	_, err = Do(context.Background(), http.MethodPost, "/nodes/:val", val5)
+	assert.NotNil(t, err)
+}

rest/httpc/service.go

@@ -1,6 +1,7 @@
 package httpc
 
 import (
+	"context"
 	"net/http"
 
 	"github.com/zeromicro/go-zero/core/breaker"
@@ -12,6 +13,8 @@ type (
 
 	// Service represents a remote HTTP service.
 	Service interface {
+		// Do sends an HTTP request with the given arguments and returns an HTTP response.
+		Do(ctx context.Context, method, url string, data interface{}) (*http.Response, error)
 		// DoRequest sends a HTTP request to the service.
 		DoRequest(r *http.Request) (*http.Response, error)
 	}
@@ -39,6 +42,16 @@ func NewServiceWithClient(name string, cli *http.Client, opts ...Option) Service
 	}
 }
 
+// Do sends an HTTP request with the given arguments and returns an HTTP response.
+func (s namedService) Do(ctx context.Context, method, url string, data interface{}) (*http.Response, error) {
+	req, err := buildRequest(ctx, method, url, data)
+	if err != nil {
+		return nil, err
+	}
+
+	return s.DoRequest(req)
+}
+
 // DoRequest sends an HTTP request to the service.
 func (s namedService) DoRequest(r *http.Request) (*http.Response, error) {
 	return request(r, s)

rest/httpc/service_test.go

@@ -1,6 +1,7 @@
 package httpc
 
 import (
+	"context"
 	"net/http"
 	"net/http/httptest"
 	"testing"
@@ -8,7 +9,7 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
-func TestNamedService_Do(t *testing.T) {
+func TestNamedService_DoRequest(t *testing.T) {
 	svr := httptest.NewServer(http.RedirectHandler("/foo", http.StatusMovedPermanently))
 	defer svr.Close()
 	req, err := http.NewRequest(http.MethodGet, svr.URL, nil)
@@ -19,7 +20,7 @@ func TestNamedService_Do(t *testing.T) {
 	assert.NotNil(t, err)
 }
 
-func TestNamedService_Get(t *testing.T) {
+func TestNamedService_DoRequestGet(t *testing.T) {
 	svr := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		w.Header().Set("foo", r.Header.Get("foo"))
 	}))
@@ -36,7 +37,7 @@ func TestNamedService_Get(t *testing.T) {
 	assert.Equal(t, "bar", resp.Header.Get("foo"))
 }
 
-func TestNamedService_Post(t *testing.T) {
+func TestNamedService_DoRequestPost(t *testing.T) {
 	svr := httptest.NewServer(http.NotFoundHandler())
 	defer svr.Close()
 	service := NewService("foo")
@@ -47,3 +48,38 @@ func TestNamedService_Post(t *testing.T) {
 	assert.Nil(t, err)
 	assert.Equal(t, http.StatusNotFound, resp.StatusCode)
 }
+
+func TestNamedService_Do(t *testing.T) {
+	type Data struct {
+		Key    string `path:"key"`
+		Value  int    `form:"value"`
+		Header string `header:"X-Header"`
+		Body   string `json:"body"`
+	}
+
+	svr := httptest.NewServer(http.NotFoundHandler())
+	defer svr.Close()
+
+	service := NewService("foo")
+	data := Data{
+		Key:    "foo",
+		Value:  10,
+		Header: "my-header",
+		Body:   "my body",
+	}
+	resp, err := service.Do(context.Background(), http.MethodPost, svr.URL+"/nodes/:key", data)
+	assert.Nil(t, err)
+	assert.Equal(t, http.StatusNotFound, resp.StatusCode)
+}
+
+func TestNamedService_DoBadRequest(t *testing.T) {
+	val := struct {
+		Value string `json:"value,options=[a,b]"`
+	}{
+		Value: "c",
+	}
+
+	service := NewService("foo")
+	_, err := service.Do(context.Background(), http.MethodPost, "/nodes/:key", val)
+	assert.NotNil(t, err)
+}

rest/httpc/vars.go

@@ -1,6 +1,17 @@
 package httpc
 
+import "errors"
+
 const (
+	pathKey         = "path"
+	formKey         = "form"
+	headerKey       = "header"
+	jsonKey         = "json"
+	slash           = "/"
+	colon           = ':'
 	contentType     = "Content-Type"
 	applicationJson = "application/json"
 )
+
+// ErrGetWithBody indicates that GET request with body.
+var ErrGetWithBody = errors.New("HTTP GET should not have body")