fix(gdb): handle empty string in Fields() gracefully

When Fields("") is called with empty string parameter, it now ignores
the empty string and behaves as if Fields() was not called, resulting
in SELECT * instead of invalid SQL "SELECT FROM table".

Also handles mixed cases like Fields("", "id") and Fields("id", "", "nickname")
by filtering out empty strings while keeping valid field names.

Fixes gogf#4697

Author: lingcoder

contrib/drivers/mysql/mysql_z_unit_issue_test.go

@@ -1949,3 +1949,37 @@ func Test_Issue4500(t *testing.T) {
 		t.Assert(len(all), 3)
 	})
 }
+
+// https://github.com/gogf/gf/issues/4697
+func Test_Issue4697(t *testing.T) {
+	table := createInitTable()
+	defer dropTable(table)
+
+	gtest.C(t, func(t *gtest.T) {
+		// Fields("") should be treated as Fields() and select all fields
+		result, err := db.Model(table).Fields("").Limit(1).All()
+		t.AssertNil(err)
+		t.AssertGT(len(result), 0)
+		// Should have all fields (id, passport, password, nickname, create_time, create_date)
+		t.Assert(len(result[0]), 6)
+	})
+
+	gtest.C(t, func(t *gtest.T) {
+		// Fields("", "id") should ignore empty string and only select "id"
+		result, err := db.Model(table).Fields("", "id").Limit(1).All()
+		t.AssertNil(err)
+		t.AssertGT(len(result), 0)
+		t.Assert(len(result[0]), 1)
+		t.AssertNE(result[0]["id"], nil)
+	})
+
+	gtest.C(t, func(t *gtest.T) {
+		// Fields("id", "", "nickname") should ignore empty string
+		result, err := db.Model(table).Fields("id", "", "nickname").Limit(1).All()
+		t.AssertNil(err)
+		t.AssertGT(len(result), 0)
+		t.Assert(len(result[0]), 2)
+		t.AssertNE(result[0]["id"], nil)
+		t.AssertNE(result[0]["nickname"], nil)
+	})
+}

database/gdb/gdb_model_fields.go

@@ -28,7 +28,18 @@ func (m *Model) Fields(fieldNamesOrMapStruct ...any) *Model {
 	if length == 0 {
 		return m
 	}
-	fields := m.filterFieldsFrom(m.tablesInit, fieldNamesOrMapStruct...)
+	// Filter out empty string fields.
+	filtered := make([]any, 0, length)
+	for _, field := range fieldNamesOrMapStruct {
+		if s, ok := field.(string); ok && s == "" {
+			continue
+		}
+		filtered = append(filtered, field)
+	}
+	if len(filtered) == 0 {
+		return m
+	}
+	fields := m.filterFieldsFrom(m.tablesInit, filtered...)
 	if len(fields) == 0 {
 		return m
 	}