refactor: extracted common logic for column aliasing

internal/jet/column_list.go

@@ -1,7 +1,5 @@
 package jet
 
-import "strings"
-
 // ColumnList is a helper type to support list of columns as single projection
 type ColumnList []ColumnExpression
 
@@ -46,12 +44,9 @@ func (cl ColumnList) Except(excludedColumns ...Column) ColumnList {
 // For instance: If projection list has a column 'Artist.Name', and tableAlias is 'Musician.*', returned projection list will
 // have a column wrapped in alias 'Musician.Name'. If tableAlias is empty string, it removes existing table alias ('Artist.Name' becomes 'Name').
 func (cl ColumnList) As(tableAlias string) ProjectionList {
-	if tableAlias > "" {
-		tableAlias = strings.TrimRight(tableAlias, ".*") + "."
-	}
 	ret := make(ProjectionList, 0, len(cl))
 	for _, c := range cl {
-		ret = append(ret, c.AS(tableAlias+c.Name()))
+		ret = append(ret, c.AS(joinAlias(tableAlias, c.Name())))
 	}
 	return ret
 }

internal/jet/projection.go

@@ -1,7 +1,5 @@
 package jet
 
-import "strings"
-
 // Projection is interface for all projection types. Types that can be part of, for instance SELECT clause.
 type Projection interface {
 	serializeForProjection(statement StatementType, out *SQLBuilder)
@@ -35,12 +33,6 @@ func (pl ProjectionList) serializeForProjection(statement StatementType, out *SQ
 // For instance: If projection list has a column 'Artist.Name', and tableAlias is 'Musician.*', returned projection list will
 // have a column wrapped in alias 'Musician.Name'. If tableAlias is empty string, it removes existing table alias ('Artist.Name' becomes 'Name').
 func (pl ProjectionList) As(tableAlias string) ProjectionList {
-	tableAliasWithDot := ""
-	if tableAlias != "" {
-		tableAlias = strings.TrimRight(tableAlias, ".*")
-		tableAliasWithDot = tableAlias + "."
-	}
-
 	newProjectionList := ProjectionList{}
 
 	for _, projection := range pl {
@@ -50,11 +42,11 @@ func (pl ProjectionList) As(tableAlias string) ProjectionList {
 		case ColumnList:
 			newProjectionList = append(newProjectionList, p.As(tableAlias))
 		case ColumnExpression:
-			newProjectionList = append(newProjectionList, newAlias(p, tableAliasWithDot+p.Name()))
+			newProjectionList = append(newProjectionList, newAlias(p, joinAlias(tableAlias, p.Name())))
 		case *alias:
 			newAlias := *p
 			_, columnName := extractTableAndColumnName(newAlias.alias)
-			newAlias.alias = tableAliasWithDot + columnName
+			newAlias.alias = joinAlias(tableAlias, columnName)
 			newProjectionList = append(newProjectionList, &newAlias)
 		}
 	}

internal/jet/utils.go

@@ -1,10 +1,11 @@
 package jet
 
 import (
-	"github.com/go-jet/jet/v2/internal/utils/dbidentifier"
-	"github.com/go-jet/jet/v2/internal/utils/must"
 	"reflect"
 	"strings"
+
+	"github.com/go-jet/jet/v2/internal/utils/dbidentifier"
+	"github.com/go-jet/jet/v2/internal/utils/must"
 )
 
 // SerializeClauseList func
@@ -278,3 +279,15 @@ func serializeToDefaultDebugString(expr Serializer) string {
 	expr.serialize(SelectStatementType, &out)
 	return out.Buff.String()
 }
+
+// joinAlias examples:
+//
+//	joinAlias("foo", "bar") // "foo.bar"
+//	joinAlias("foo.*", "bar") // "foo.bar"
+//	joinAlias("", "bar") // "bar"
+func joinAlias(tableAlias, columnAlias string) string {
+	if tableAlias == "" {
+		return columnAlias
+	}
+	return strings.TrimRight(tableAlias, ".*") + "." + columnAlias
+}

internal/jet/utils_test.go

@@ -1,8 +1,9 @@
 package jet
 
 import (
-	"github.com/stretchr/testify/require"
 	"testing"
+
+	"github.com/stretchr/testify/require"
 )
 
 func TestOptionalOrDefaultString(t *testing.T) {
@@ -17,3 +18,10 @@ func TestOptionalOrDefaultExpression(t *testing.T) {
 	require.Equal(t, OptionalOrDefaultExpression(defaultExpression), defaultExpression)
 	require.Equal(t, OptionalOrDefaultExpression(defaultExpression, optionalExpression), optionalExpression)
 }
+
+func TestJoinAlias(t *testing.T) {
+	require.Equal(t, joinAlias("", ""), "")
+	require.Equal(t, joinAlias("foo", "bar"), "foo.bar")
+	require.Equal(t, joinAlias("foo.*", "bar"), "foo.bar")
+	require.Equal(t, joinAlias("", "bar"), "bar")
+}