feat(database/gdb): add Exist support for checking records existance for certain condition (#3854)

contrib/drivers/clickhouse/clickhouse_z_unit_model_test.go

@@ -258,6 +258,19 @@ func Test_Model_Count(t *testing.T) {
 	})
 }
 
+func Test_Model_Exist(t *testing.T) {
+	table := createInitTable()
+	defer dropTable(table)
+	gtest.C(t, func(t *gtest.T) {
+		exist, err := db.Model(table).Exist()
+		t.AssertNil(err)
+		t.Assert(exist, TableSize > 0)
+		exist, err = db.Model(table).Where("id", -1).Exist()
+		t.AssertNil(err)
+		t.Assert(exist, false)
+	})
+}
+
 func Test_Model_Where(t *testing.T) {
 	table := createInitTable()
 	defer dropTable(table)

contrib/drivers/mssql/mssql_z_unit_model_test.go

@@ -519,7 +519,19 @@ func Test_Model_Count(t *testing.T) {
 		t.AssertNil(err)
 		t.Assert(count, int64(TableSize))
 	})
+}
 
+func Test_Model_Exist(t *testing.T) {
+	table := createInitTable()
+	defer dropTable(table)
+	gtest.C(t, func(t *gtest.T) {
+		exist, err := db.Model(table).Exist()
+		t.AssertNil(err)
+		t.Assert(exist, TableSize > 0)
+		exist, err = db.Model(table).Where("id", -1).Exist()
+		t.AssertNil(err)
+		t.Assert(exist, false)
+	})
 }
 
 func Test_Model_Select(t *testing.T) {

contrib/drivers/mysql/mysql_z_unit_model_test.go

@@ -734,6 +734,19 @@ func Test_Model_Count(t *testing.T) {
 	})
 }
 
+func Test_Model_Exist(t *testing.T) {
+	table := createInitTable()
+	defer dropTable(table)
+	gtest.C(t, func(t *gtest.T) {
+		exist, err := db.Model(table).Exist()
+		t.AssertNil(err)
+		t.Assert(exist, TableSize > 0)
+		exist, err = db.Model(table).Where("id", -1).Exist()
+		t.AssertNil(err)
+		t.Assert(exist, false)
+	})
+}
+
 func Test_Model_Value_WithCache(t *testing.T) {
 	table := createTable()
 	defer dropTable(table)

contrib/drivers/oracle/oracle_z_unit_model_test.go

@@ -460,6 +460,19 @@ func Test_Model_Count(t *testing.T) {
 
 }
 
+func Test_Model_Exist(t *testing.T) {
+	table := createInitTable()
+	defer dropTable(table)
+	gtest.C(t, func(t *gtest.T) {
+		exist, err := db.Model(table).Exist()
+		t.AssertNil(err)
+		t.Assert(exist, TableSize > 0)
+		exist, err = db.Model(table).Where("id", -1).Exist()
+		t.AssertNil(err)
+		t.Assert(exist, false)
+	})
+}
+
 func Test_Model_Select(t *testing.T) {
 	table := createInitTable()
 	defer dropTable(table)

contrib/drivers/pgsql/pgsql_z_unit_model_test.go

@@ -226,6 +226,19 @@ func Test_Model_Count(t *testing.T) {
 	})
 }
 
+func Test_Model_Exist(t *testing.T) {
+	table := createInitTable()
+	defer dropTable(table)
+	gtest.C(t, func(t *gtest.T) {
+		exist, err := db.Model(table).Exist()
+		t.AssertNil(err)
+		t.Assert(exist, TableSize > 0)
+		exist, err = db.Model(table).Where("id", -1).Exist()
+		t.AssertNil(err)
+		t.Assert(exist, false)
+	})
+}
+
 func Test_Model_Where(t *testing.T) {
 	table := createInitTable()
 	defer dropTable(table)

contrib/drivers/sqlite/sqlite_z_unit_model_test.go

@@ -865,6 +865,19 @@ func Test_Model_Count(t *testing.T) {
 	})
 }
 
+func Test_Model_Exist(t *testing.T) {
+	table := createInitTable()
+	defer dropTable(table)
+	gtest.C(t, func(t *gtest.T) {
+		exist, err := db.Model(table).Exist()
+		t.AssertNil(err)
+		t.Assert(exist, TableSize > 0)
+		exist, err = db.Model(table).Where("id", -1).Exist()
+		t.AssertNil(err)
+		t.Assert(exist, false)
+	})
+}
+
 func Test_Model_Select(t *testing.T) {
 	table := createInitTable()
 	defer dropTable(table)

contrib/drivers/sqlitecgo/sqlitecgo_z_unit_model_test.go

@@ -824,6 +824,19 @@ func Test_Model_Count(t *testing.T) {
 	})
 }
 
+func Test_Model_Exist(t *testing.T) {
+	table := createInitTable()
+	defer dropTable(table)
+	gtest.C(t, func(t *gtest.T) {
+		exist, err := db.Model(table).Exist()
+		t.AssertNil(err)
+		t.Assert(exist, TableSize > 0)
+		exist, err = db.Model(table).Where("id", -1).Exist()
+		t.AssertNil(err)
+		t.Assert(exist, false)
+	})
+}
+
 func Test_Model_Select(t *testing.T) {
 	table := createInitTable()
 	defer dropTable(table)

database/gdb/gdb_model_select.go

@@ -467,6 +467,25 @@ func (m *Model) Count(where ...interface{}) (int, error) {
 	return 0, nil
 }
 
+// Exist does "SELECT 1 FROM ... LIMIT 1" statement for the model.
+// The optional parameter `where` is the same as the parameter of Model.Where function,
+// see Model.Where.
+func (m *Model) Exist(where ...interface{}) (bool, error) {
+	if len(where) > 0 {
+		return m.Where(where[0], where[1:]...).Exist()
+	}
+	one, err := m.Fields(Raw("1")).One()
+	if err != nil {
+		return false, err
+	}
+	for _, val := range one {
+		if val.Bool() {
+			return true, nil
+		}
+	}
+	return false, nil
+}
+
 // CountColumn does "SELECT COUNT(x) FROM ..." statement for the model.
 func (m *Model) CountColumn(column string) (int, error) {
 	if len(column) == 0 {