Fix query using table alias (#73)

Author: Fs02

builder/buffer.go

@@ -131,35 +131,40 @@ func (b Buffer) escape(table, value string) string {
 		return escapedValue.(string)
 	}
 
-	var escaped_table string
+	table, alias := extractAlias(table)
+	var escapedTable string
 	if table != "" {
-		if i := strings.Index(strings.ToLower(table), " as "); i > -1 {
-			return b.escape(table[:i], "") + " AS " + b.Quoter.ID(table[i+4:])
+		if table != alias {
+			if value == "" {
+				return b.escape(table, "") + " AS " + b.Quoter.ID(alias)
+			} else {
+				escapedTable = b.Quoter.ID(alias)
+			}
 		}
 		if b.AllowTableSchema && strings.IndexByte(table, '.') >= 0 {
 			parts := strings.Split(table, ".")
 			for i, part := range parts {
 				part = strings.TrimSpace(part)
 				parts[i] = b.Quoter.ID(part)
 			}
-			escaped_table = strings.Join(parts, ".")
+			escapedTable = strings.Join(parts, ".")
 		} else {
-			escaped_table = b.Quoter.ID(strings.ReplaceAll(table, ".", "_"))
+			escapedTable = b.Quoter.ID(strings.ReplaceAll(table, ".", "_"))
 		}
 	}
 
 	if value == "" {
-		escapedValue = escaped_table
+		escapedValue = escapedTable
 	} else if value == "*" {
-		escapedValue = escaped_table + ".*"
+		escapedValue = escapedTable + ".*"
 	} else if len(value) > 0 && value[0] == UnescapeCharacter {
 		escapedValue = value[1:]
 	} else if _, err := strconv.Atoi(value); err == nil {
 		escapedValue = value
 	} else if i := strings.Index(strings.ToLower(value), " as "); i > -1 {
-		escapedValue = b.escape(table, value[:i]) + " AS " + b.Quoter.ID(value[i+4:])
+		escapedValue = b.escape(alias, value[:i]) + " AS " + b.Quoter.ID(value[i+4:])
 	} else if start, end := strings.IndexRune(value, '('), strings.IndexRune(value, ')'); start >= 0 && end >= 0 && end > start {
-		escapedValue = value[:start+1] + b.escape(table, value[start+1:end]) + value[end:]
+		escapedValue = value[:start+1] + b.escape(alias, value[start+1:end]) + value[end:]
 	} else {
 		parts := strings.Split(value, ".")
 		for i, part := range parts {
@@ -171,7 +176,7 @@ func (b Buffer) escape(table, value string) string {
 		}
 		result := strings.Join(parts, ".")
 		if len(parts) == 1 && table != "" {
-			result = escaped_table + "." + result
+			result = escapedTable + "." + result
 		}
 		escapedValue = result
 	}
@@ -228,3 +233,13 @@ func (bf BufferFactory) Create() Buffer {
 		BoolFalseValue:      bf.BoolFalseValue,
 	}
 }
+
+// extract alias in the form of table as alias
+// if no alias, table will be returned as alias
+func extractAlias(input string) (string, string) {
+	if i := strings.Index(strings.ToLower(input), " as "); i > -1 {
+		return input[:i], input[i+4:]
+	}
+
+	return input, input
+}

builder/query.go

@@ -105,20 +105,16 @@ func (q Query) WriteJoin(buffer *Buffer, table string, joins []rel.JoinQuery) {
 
 	for _, join := range joins {
 		var (
-			from = join.From
-			to   = join.To
+			_, sAlias      = extractAlias(table)
+			jTable, jAlias = extractAlias(join.Table)
+			from           = join.From
+			to             = join.To
 		)
 
-		jtable := join.Table
-		// If join table has alias use that for filter conditions
-		if i := strings.Index(strings.ToLower(jtable), " as "); i > -1 {
-			jtable = jtable[i+4:]
-		}
-
 		// TODO: move this to core functionality, and infer join condition using assoc data.
 		if join.Arguments == nil && (join.From == "" || join.To == "") {
-			from = table + "." + strings.TrimSuffix(join.Table, "s") + "_id"
-			to = jtable + ".id"
+			from = sAlias + "." + strings.TrimSuffix(jTable, "s") + "_id"
+			to = jAlias + ".id"
 		}
 
 		buffer.WriteByte(' ')
@@ -133,7 +129,7 @@ func (q Query) WriteJoin(buffer *Buffer, table string, joins []rel.JoinQuery) {
 			buffer.WriteEscape(to)
 			if !join.Filter.None() {
 				buffer.WriteString(" AND ")
-				q.Filter.Write(buffer, jtable, join.Filter, q)
+				q.Filter.Write(buffer, join.Table, join.Filter, q)
 			}
 		}
 

builder/query_test.go

@@ -105,6 +105,36 @@ func TestQuery_Build(t *testing.T) {
 			result: "SELECT `users`.* FROM `users` FOR UPDATE;",
 			query:  rel.From("users").Lock("FOR UPDATE"),
 		},
+		{
+			result: "SELECT `c`.`id`,`c`.`name` FROM `contacts` AS `c`;",
+			query:  rel.Select("c.id", "c.name").From("contacts as c"),
+		},
+		{
+			result: "SELECT MAX(`c`.`id`) FROM `contacts` AS `c`;",
+			query:  rel.Select("MAX(id)").From("contacts as c"),
+		},
+		{
+			result: "SELECT MAX(`c`.`id`) FROM `contacts` AS `c`;",
+			query:  rel.Select("MAX(c.id)").From("contacts as c"),
+		},
+		{
+			result: "SELECT MAX(`c`.`id`) AS `max_id` FROM `contacts` AS `c`;",
+			query:  rel.Select("MAX(id) as max_id").From("contacts as c"),
+		},
+		{
+			result: "SELECT MAX(`c`.`id`) AS `max_id` FROM `contacts` AS `c`;",
+			query:  rel.Select("MAX(c.id) as max_id").From("contacts as c"),
+		},
+		{
+			result: "SELECT `c`.`id`,`c`.`name` FROM `contacts` AS `c` JOIN `users` AS `u` ON `c`.`user_id`=`u`.`id` WHERE `u`.`active`=?;",
+			args:   []any{true},
+			query:  rel.Select("c.id", "c.name").From("contacts as c").Join("users as u").Where(rel.Eq("u.active", true)),
+		},
+		{
+			result: "SELECT `c`.`id`,`c`.`name` FROM `contacts` AS `c` JOIN `users` AS `u` ON `u`.`id`=`c`.`user_id` WHERE `u`.`active`=?;",
+			args:   []any{true},
+			query:  rel.Select("c.id", "c.name").From("contacts as c").JoinOn("users as u", "u.id", "c.user_id").Where(rel.Eq("u.active", true)),
+		},
 	}
 
 	for _, test := range tests {