From 5d804987b9946b246826e7bce1a7805b03d101ca Mon Sep 17 00:00:00 2001
From: John Guo <john@johng.cn>
Date: Wed, 6 Oct 2021 20:11:54 +0800
Subject: [PATCH] add alias g.Meta for gmeta.Meta

---
 frame/g/g.go                                  |  6 ++-
 util/gmeta/gmeta.go                           | 12 ++++--
 .../{gmeta_test.go => gmeta_bench_test.go}    | 19 ----------
 util/gmeta/gmeta_unit_test.go                 | 38 +++++++++++++++++++
 4 files changed, 50 insertions(+), 25 deletions(-)
 rename util/gmeta/{gmeta_test.go => gmeta_bench_test.go} (71%)
 create mode 100644 util/gmeta/gmeta_unit_test.go

diff --git a/frame/g/g.go b/frame/g/g.go
index c8d4163e7..be1cbef2d 100644
--- a/frame/g/g.go
+++ b/frame/g/g.go
@@ -9,11 +9,13 @@ package g
 import (
 	"context"
 	"github.com/gogf/gf/container/gvar"
+	"github.com/gogf/gf/util/gmeta"
 )
 
 type (
-	Var = gvar.Var        // Var is a universal variable interface, like generics.
-	Ctx = context.Context // Ctx is alias of frequently-used context.Context.
+	Var  = gvar.Var        // Var is a universal variable interface, like generics.
+	Ctx  = context.Context // Ctx is alias of frequently-used type context.Context.
+	Meta = gmeta.Meta      // Meta is alias of frequently-used type gmeta.Meta.
 )
 
 type (
diff --git a/util/gmeta/gmeta.go b/util/gmeta/gmeta.go
index c522fcd7b..d81e13ed2 100644
--- a/util/gmeta/gmeta.go
+++ b/util/gmeta/gmeta.go
@@ -12,16 +12,16 @@ import (
 	"github.com/gogf/gf/internal/structs"
 )
 
-// Meta is used as an embedded attribute for struct to enabled meta data feature.
+// Meta is used as an embedded attribute for struct to enabled metadata feature.
 type Meta struct{}
 
 const (
-	// metaAttributeName is the attribute name of meta data in struct.
+	// metaAttributeName is the attribute name of metadata in struct.
 	metaAttributeName = "Meta"
 )
 
 // Data retrieves and returns all metadata from `object`.
-// It automatically parses and caches the tag string from "Mata" attribute as its meta data.
+// It automatically parses and caches the tag string from "Mata" attribute as its metadata.
 func Data(object interface{}) map[string]interface{} {
 	reflectType, err := structs.StructType(object)
 	if err != nil {
@@ -42,5 +42,9 @@ func Data(object interface{}) map[string]interface{} {
 
 // Get retrieves and returns specified metadata by `key` from `object`.
 func Get(object interface{}, key string) *gvar.Var {
-	return gvar.New(Data(object)[key])
+	v := Data(object)[key]
+	if v == nil {
+		return nil
+	}
+	return gvar.New(v)
 }
diff --git a/util/gmeta/gmeta_test.go b/util/gmeta/gmeta_bench_test.go
similarity index 71%
rename from util/gmeta/gmeta_test.go
rename to util/gmeta/gmeta_bench_test.go
index 2186d5414..6858ba534 100644
--- a/util/gmeta/gmeta_test.go
+++ b/util/gmeta/gmeta_bench_test.go
@@ -7,11 +7,8 @@
 package gmeta_test
 
 import (
-	"github.com/gogf/gf/internal/json"
 	"github.com/gogf/gf/util/gmeta"
 	"testing"
-
-	"github.com/gogf/gf/test/gtest"
 )
 
 type A struct {
@@ -60,19 +57,3 @@ func Benchmark_Data_Get_Pointer2(b *testing.B) {
 		gmeta.Get(&a2, "tag")
 	}
 }
-
-func TestMeta_Basic(t *testing.T) {
-	gtest.C(t, func(t *gtest.T) {
-		a := &A{
-			Id:   100,
-			Name: "john",
-		}
-		t.Assert(len(gmeta.Data(a)), 2)
-		t.Assert(gmeta.Get(a, "tag").String(), "123")
-		t.Assert(gmeta.Get(a, "orm").String(), "456")
-
-		b, err := json.Marshal(a)
-		t.AssertNil(err)
-		t.Assert(b, `{"Id":100,"Name":"john"}`)
-	})
-}
diff --git a/util/gmeta/gmeta_unit_test.go b/util/gmeta/gmeta_unit_test.go
new file mode 100644
index 000000000..71e310529
--- /dev/null
+++ b/util/gmeta/gmeta_unit_test.go
@@ -0,0 +1,38 @@
+// Copyright GoFrame Author(https://goframe.org). All Rights Reserved.
+//
+// This Source Code Form is subject to the terms of the MIT License.
+// If a copy of the MIT was not distributed with this file,
+// You can obtain one at https://github.com/gogf/gf.
+
+package gmeta_test
+
+import (
+	"github.com/gogf/gf/internal/json"
+	"github.com/gogf/gf/util/gmeta"
+	"testing"
+
+	"github.com/gogf/gf/test/gtest"
+)
+
+func TestMeta_Basic(t *testing.T) {
+	type A struct {
+		gmeta.Meta `tag:"123" orm:"456"`
+		Id         int
+		Name       string
+	}
+
+	gtest.C(t, func(t *gtest.T) {
+		a := &A{
+			Id:   100,
+			Name: "john",
+		}
+		t.Assert(len(gmeta.Data(a)), 2)
+		t.AssertEQ(gmeta.Get(a, "tag").String(), "123")
+		t.AssertEQ(gmeta.Get(a, "orm").String(), "456")
+		t.AssertEQ(gmeta.Get(a, "none"), nil)
+
+		b, err := json.Marshal(a)
+		t.AssertNil(err)
+		t.Assert(b, `{"Id":100,"Name":"john"}`)
+	})
+}