add ScanStructs, ScanVals to Scanner interface

exec/query_executor.go

@@ -79,18 +79,15 @@ func (q QueryExecutor) ScanStructs(i interface{}) error {
 //
 // i: A pointer to a slice of structs.
 func (q QueryExecutor) ScanStructsContext(ctx context.Context, i interface{}) error {
-	val := reflect.ValueOf(i)
-	if !util.IsPointer(val.Kind()) {
-		return errUnsupportedScanStructsType
+	if _, err := checkScanStructsTarget(i); err != nil {
+		return err
 	}
-	val = reflect.Indirect(val)
-	if !util.IsSlice(val.Kind()) {
-		return errUnsupportedScanStructsType
+	scanner, err := q.ScannerContext(ctx)
+	if err != nil {
+		return err
 	}
-
-	return q.scanIntoSlice(ctx, val, func(sc Scanner, r interface{}) error {
-		return sc.ScanStruct(r)
-	})
+	defer func() { _ = scanner.Close() }()
+	return scanner.ScanStructs(i)
 }
 
 // This will execute the SQL and fill out the struct with the fields returned.
@@ -136,7 +133,7 @@ func (q QueryExecutor) ScanStructContext(ctx context.Context, i interface{}) (bo
 		return false, err
 	}
 
-	defer scanner.Close()
+	defer func() { _ = scanner.Close() }()
 
 	if scanner.Next() {
 		err = scanner.ScanStruct(i)
@@ -169,18 +166,15 @@ func (q QueryExecutor) ScanVals(i interface{}) error {
 //
 // i: Takes a pointer to a slice of primitive values.
 func (q QueryExecutor) ScanValsContext(ctx context.Context, i interface{}) error {
-	val := reflect.ValueOf(i)
-	if !util.IsPointer(val.Kind()) {
-		return errUnsupportedScanValsType
+	if _, err := checkScanValsTarget(i); err != nil {
+		return err
 	}
-	val = reflect.Indirect(val)
-	if !util.IsSlice(val.Kind()) {
-		return errUnsupportedScanValsType
+	scanner, err := q.ScannerContext(ctx)
+	if err != nil {
+		return err
 	}
-
-	return q.scanIntoSlice(ctx, val, func(sc Scanner, r interface{}) error {
-		return sc.ScanVal(r)
-	})
+	defer func() { _ = scanner.Close() }()
+	return scanner.ScanVals(i)
 }
 
 // This will execute the SQL and set the value of the primitive. This method will return false if no record is found.
@@ -230,7 +224,7 @@ func (q QueryExecutor) ScanValContext(ctx context.Context, i interface{}) (bool,
 		return false, err
 	}
 
-	defer scanner.Close()
+	defer func() { _ = scanner.Close() }()
 
 	if scanner.Next() {
 		err = scanner.ScanVal(i)
@@ -257,26 +251,3 @@ func (q QueryExecutor) ScannerContext(ctx context.Context) (Scanner, error) {
 	}
 	return NewScanner(rows), nil
 }
-
-func (q QueryExecutor) scanIntoSlice(ctx context.Context, val reflect.Value, it func(sc Scanner, i interface{}) error) error {
-	elemType := util.GetSliceElementType(val)
-
-	scanner, err := q.ScannerContext(ctx)
-	if err != nil {
-		return err
-	}
-
-	defer scanner.Close()
-
-	for scanner.Next() {
-		row := reflect.New(elemType)
-		err = it(scanner, row.Interface())
-		if err != nil {
-			return err
-		}
-
-		util.AppendSliceElement(val, row)
-	}
-
-	return scanner.Err()
-}

exec/scanner.go

@@ -14,7 +14,9 @@ type (
 	Scanner interface {
 		Next() bool
 		ScanStruct(i interface{}) error
+		ScanStructs(i interface{}) error
 		ScanVal(i interface{}) error
+		ScanVals(i interface{}) error
 		Close() error
 		Err() error
 	}
@@ -90,6 +92,17 @@ func (s *scanner) ScanStruct(i interface{}) error {
 	return s.Err()
 }
 
+// ScanStructs scans results in slice of structs
+func (s *scanner) ScanStructs(i interface{}) error {
+	val, err := checkScanStructsTarget(i)
+	if err != nil {
+		return err
+	}
+	return s.scanIntoSlice(val, func(i interface{}) error {
+		return s.ScanStruct(i)
+	})
+}
+
 // ScanVal will scan the current row and column into i.
 func (s *scanner) ScanVal(i interface{}) error {
 	if err := s.rows.Scan(i); err != nil {
@@ -99,8 +112,57 @@ func (s *scanner) ScanVal(i interface{}) error {
 	return s.Err()
 }
 
+// ScanStructs scans results in slice of values
+func (s *scanner) ScanVals(i interface{}) error {
+	val, err := checkScanValsTarget(i)
+	if err != nil {
+		return err
+	}
+	return s.scanIntoSlice(val, func(i interface{}) error {
+		return s.ScanVal(i)
+	})
+}
+
 // Close closes the Rows, preventing further enumeration. See sql.Rows#Close
 // for more info.
 func (s *scanner) Close() error {
 	return s.rows.Close()
 }
+
+func (s *scanner) scanIntoSlice(val reflect.Value, it func(i interface{}) error) error {
+	elemType := util.GetSliceElementType(val)
+
+	for s.Next() {
+		row := reflect.New(elemType)
+		if rowErr := it(row.Interface()); rowErr != nil {
+			return rowErr
+		}
+		util.AppendSliceElement(val, row)
+	}
+
+	return s.Err()
+}
+
+func checkScanStructsTarget(i interface{}) (reflect.Value, error) {
+	val := reflect.ValueOf(i)
+	if !util.IsPointer(val.Kind()) {
+		return val, errUnsupportedScanStructsType
+	}
+	val = reflect.Indirect(val)
+	if !util.IsSlice(val.Kind()) {
+		return val, errUnsupportedScanStructsType
+	}
+	return val, nil
+}
+
+func checkScanValsTarget(i interface{}) (reflect.Value, error) {
+	val := reflect.ValueOf(i)
+	if !util.IsPointer(val.Kind()) {
+		return val, errUnsupportedScanValsType
+	}
+	val = reflect.Indirect(val)
+	if !util.IsSlice(val.Kind()) {
+		return val, errUnsupportedScanValsType
+	}
+	return val, nil
+}

exec/scanner_internal_test.go

@@ -0,0 +1,69 @@
+package exec
+
+import (
+	"testing"
+
+	"github.com/DATA-DOG/go-sqlmock"
+	"github.com/stretchr/testify/suite"
+)
+
+type scannerSuite struct {
+	suite.Suite
+}
+
+func TestScanner(t *testing.T) {
+	suite.Run(t, &scannerSuite{})
+}
+
+func (s *scannerSuite) TestScanStructs() {
+	type StructWithTags struct {
+		Address string `db:"address"`
+		Name    string `db:"name"`
+	}
+	db, mock, err := sqlmock.New()
+	s.Require().NoError(err)
+
+	mock.ExpectQuery(`SELECT \* FROM "items"`).
+		WithArgs().
+		WillReturnRows(sqlmock.NewRows([]string{"address", "name"}).
+			AddRow(testAddr1, testName1).
+			AddRow(testAddr2, testName2),
+		)
+	rows, err := db.Query(`SELECT * FROM "items"`)
+	s.Require().NoError(err)
+
+	sc := NewScanner(rows)
+
+	result := make([]StructWithTags, 0)
+	err = sc.ScanStructs(result)
+	s.Require().EqualError(err, errUnsupportedScanStructsType.Error())
+
+	err = sc.ScanStructs(&result)
+	s.Require().NoError(err)
+	s.Require().ElementsMatch(
+		[]StructWithTags{{Address: testAddr1, Name: testName1}, {Address: testAddr2, Name: testName2}},
+		result,
+	)
+}
+
+func (s *scannerSuite) TestScanVals() {
+	db, mock, err := sqlmock.New()
+	s.Require().NoError(err)
+
+	mock.ExpectQuery(`SELECT "id" FROM "items"`).
+		WithArgs().
+		WillReturnRows(sqlmock.NewRows([]string{"id"}).AddRow(1).AddRow(2))
+
+	rows, err := db.Query(`SELECT "id" FROM "items"`)
+	s.Require().NoError(err)
+
+	sc := NewScanner(rows)
+
+	result := make([]int, 0)
+	err = sc.ScanVals(result)
+	s.Require().EqualError(err, errUnsupportedScanValsType.Error())
+
+	err = sc.ScanVals(&result)
+	s.Require().NoError(err)
+	s.Require().ElementsMatch([]int{1, 2}, result)
+}