add mapper that applies to sql columns

Author: Minnowo

reflectx/reflect.go

@@ -65,6 +65,7 @@ type Mapper struct {
 	tagName    string
 	tagMapFunc func(string) string
 	mapFunc    func(string) string
+	colMapFunc func(string) string
 	mutex      sync.Mutex
 }
 
@@ -89,6 +90,19 @@ func NewMapperTagFunc(tagName string, mapFunc, tagMapFunc func(string) string) *
 	}
 }
 
+// NewMapperTagColFunc returns a new mapper which contains a mapper for field names
+// AND a mapper for tag values AND sql column names.  This is useful for tags like json which can
+// have values like "name,omitempty", or on databases like Sqlite where column casing in queries cause problems.
+func NewMapperTagColFunc(tagName string, mapFunc, tagMapFunc, colMapFunc func(string) string) *Mapper {
+	return &Mapper{
+		cache:      make(map[reflect.Type]*StructMap),
+		tagName:    tagName,
+		mapFunc:    mapFunc,
+		tagMapFunc: tagMapFunc,
+		colMapFunc: colMapFunc,
+	}
+}
+
 // NewMapperFunc returns a new mapper which optionally obeys a field tag and
 // a struct field name mapper func given by f.  Tags will take precedence, but
 // for any other field, the mapped name will be f(field.Name)
@@ -189,6 +203,9 @@ func (m *Mapper) TraversalsByNameFunc(t reflect.Type, names []string, fn func(in
 	nameCounter := make(map[string]int, len(names))
 
 	for i, name := range names {
+		if m.colMapFunc != nil {
+			name = m.colMapFunc(name)
+		}
 		fi, ok := tm.Names[name]
 		if !ok {
 			if leafs, lok := tm.Leafs[name]; lok {

sqlx_test.go

@@ -815,7 +815,7 @@ func TestNamedQuery(t *testing.T) {
 					t.Errorf("Expected LastName of `smith`, got `%s` (%s)", jp.LastName.String, db.DriverName())
 				}
 				if jp.Email.String != "ben@smith.com" {
-					t.Errorf("Expected first name of `doe`, got `%s` (%s)", jp.Email.String, db.DriverName())
+					t.Errorf("Expected email of `ben@smith.com`, got `%s` (%s)", jp.Email.String, db.DriverName())
 				}
 			}
 		}
@@ -852,6 +852,24 @@ func TestNamedQuery(t *testing.T) {
 
 		check(t, rows)
 
+		// Test the new col mapper which maps the sql column names also.
+		db.Mapper = reflectx.NewMapperTagColFunc("json", strings.ToLower, strings.ToLower, strings.ToLower)
+
+		// Sqlite will return the column names with the same case as we wrote in the query.
+		// So in queries with mixed casing, it will cause problems.
+		rows, err = db.NamedQuery(pdb(`
+			SELECT "FIRST" as fIrSt, last_name as LAST_NAME, "EMAIL" as email FROM jsperson
+			WHERE
+				"FIRST"=:FIRST AND
+				last_name=:last_name AND
+				"EMAIL"=:EMAIL
+		`, db), jp)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		check(t, rows)
+
 		db.Mapper = old
 
 		// Test nested structs