Replacer interface for more flexible NamingStrategy (#4042)

* Change NameReplacer to an interface, allowing custom Replacers.

* Add NoLowerCase option to skip the snake_casing of names.

* Move sync.Map from global variable into member of NamingStrategy.

This maintains backward compatibility by making the smap optional - the
NamingStrategy still works if it is nil. gorm.Open activates it by
calling Init() if the given Namer is a schema.NamingStrategy.

Also, this changes the key stored in the smap to be the original name,
instead of the replaced name.

* Refactor NamingStrategy tests to add more assertions about how and when Replacers get called.

* Remove the name cache from NamingStrategy.

schema/naming.go

@@ -4,7 +4,6 @@ import (
 	"crypto/sha1"
 	"fmt"
 	"strings"
-	"sync"
 	"unicode/utf8"
 
 	"github.com/jinzhu/inflection"
@@ -20,11 +19,17 @@ type Namer interface {
 	IndexName(table, column string) string
 }
 
+// Replacer replacer interface like strings.Replacer
+type Replacer interface {
+	Replace(name string) string
+}
+
 // NamingStrategy tables, columns naming strategy
 type NamingStrategy struct {
 	TablePrefix   string
 	SingularTable bool
-	NameReplacer  *strings.Replacer
+	NameReplacer  Replacer
+	NoLowerCase   bool
 }
 
 // TableName convert string to table name
@@ -42,7 +47,7 @@ func (ns NamingStrategy) ColumnName(table, column string) string {
 
 // JoinTableName convert string to join table name
 func (ns NamingStrategy) JoinTableName(str string) string {
-	if strings.ToLower(str) == str {
+	if !ns.NoLowerCase && strings.ToLower(str) == str {
 		return ns.TablePrefix + str
 	}
 
@@ -81,7 +86,6 @@ func (ns NamingStrategy) formatName(prefix, table, name string) string {
 }
 
 var (
-	smap sync.Map
 	// https://github.com/golang/lint/blob/master/lint.go#L770
 	commonInitialisms         = []string{"API", "ASCII", "CPU", "CSS", "DNS", "EOF", "GUID", "HTML", "HTTP", "HTTPS", "ID", "IP", "JSON", "LHS", "QPS", "RAM", "RHS", "RPC", "SLA", "SMTP", "SSH", "TLS", "TTL", "UID", "UI", "UUID", "URI", "URL", "UTF8", "VM", "XML", "XSRF", "XSS"}
 	commonInitialismsReplacer *strings.Replacer
@@ -98,14 +102,16 @@ func init() {
 func (ns NamingStrategy) toDBName(name string) string {
 	if name == "" {
 		return ""
-	} else if v, ok := smap.Load(name); ok {
-		return v.(string)
 	}
 
 	if ns.NameReplacer != nil {
 		name = ns.NameReplacer.Replace(name)
 	}
 
+	if ns.NoLowerCase {
+		return name
+	}
+
 	var (
 		value                          = commonInitialismsReplacer.Replace(name)
 		buf                            strings.Builder
@@ -143,6 +149,5 @@ func (ns NamingStrategy) toDBName(name string) string {
 		buf.WriteByte(value[len(value)-1])
 	}
 	ret := buf.String()
-	smap.Store(name, ret)
 	return ret
 }

schema/naming_test.go

@@ -72,3 +72,99 @@ func TestNamingStrategy(t *testing.T) {
 		t.Errorf("invalid column name generated, got %v", columdName)
 	}
 }
+
+type CustomReplacer struct {
+	f func(string) string
+}
+
+func (r CustomReplacer) Replace(name string) string {
+	return r.f(name)
+}
+
+func TestCustomReplacer(t *testing.T) {
+	var ns = NamingStrategy{
+		TablePrefix:   "public.",
+		SingularTable: true,
+		NameReplacer: CustomReplacer{
+			func(name string) string {
+				replaced := "REPLACED_" + strings.ToUpper(name)
+				return strings.NewReplacer("CID", "_Cid").Replace(replaced)
+			},
+		},
+		NoLowerCase: false,
+	}
+
+	idxName := ns.IndexName("public.table", "name")
+	if idxName != "idx_public_table_replaced_name" {
+		t.Errorf("invalid index name generated, got %v", idxName)
+	}
+
+	chkName := ns.CheckerName("public.table", "name")
+	if chkName != "chk_public_table_name" {
+		t.Errorf("invalid checker name generated, got %v", chkName)
+	}
+
+	joinTable := ns.JoinTableName("user_languages")
+	if joinTable != "public.user_languages" { // Seems like a bug in NamingStrategy to skip the Replacer when the name is lowercase here.
+		t.Errorf("invalid join table generated, got %v", joinTable)
+	}
+
+	joinTable2 := ns.JoinTableName("UserLanguage")
+	if joinTable2 != "public.replaced_userlanguage" {
+		t.Errorf("invalid join table generated, got %v", joinTable2)
+	}
+
+	tableName := ns.TableName("Company")
+	if tableName != "public.replaced_company" {
+		t.Errorf("invalid table name generated, got %v", tableName)
+	}
+
+	columdName := ns.ColumnName("", "NameCID")
+	if columdName != "replaced_name_cid" {
+		t.Errorf("invalid column name generated, got %v", columdName)
+	}
+}
+
+func TestCustomReplacerWithNoLowerCase(t *testing.T) {
+	var ns = NamingStrategy{
+		TablePrefix:   "public.",
+		SingularTable: true,
+		NameReplacer: CustomReplacer{
+			func(name string) string {
+				replaced := "REPLACED_" + strings.ToUpper(name)
+				return strings.NewReplacer("CID", "_Cid").Replace(replaced)
+			},
+		},
+		NoLowerCase: true,
+	}
+
+	idxName := ns.IndexName("public.table", "name")
+	if idxName != "idx_public_table_REPLACED_NAME" {
+		t.Errorf("invalid index name generated, got %v", idxName)
+	}
+
+	chkName := ns.CheckerName("public.table", "name")
+	if chkName != "chk_public_table_name" {
+		t.Errorf("invalid checker name generated, got %v", chkName)
+	}
+
+	joinTable := ns.JoinTableName("user_languages")
+	if joinTable != "public.REPLACED_USER_LANGUAGES" {
+		t.Errorf("invalid join table generated, got %v", joinTable)
+	}
+
+	joinTable2 := ns.JoinTableName("UserLanguage")
+	if joinTable2 != "public.REPLACED_USERLANGUAGE" {
+		t.Errorf("invalid join table generated, got %v", joinTable2)
+	}
+
+	tableName := ns.TableName("Company")
+	if tableName != "public.REPLACED_COMPANY" {
+		t.Errorf("invalid table name generated, got %v", tableName)
+	}
+
+	columdName := ns.ColumnName("", "NameCID")
+	if columdName != "REPLACED_NAME_Cid" {
+		t.Errorf("invalid column name generated, got %v", columdName)
+	}
+}