Merge pull request #7 from networkteam/implement-iterator-function

Implement Go 1.23 iterator function for iterating rows

.github/workflows/test.yml

@@ -17,16 +17,16 @@ jobs:
       - name: Install Go
         uses: actions/setup-go@v4
         with:
-          go-version: '1.20'
+          go-version: '1.23'
       - name: golangci-lint
         uses: golangci/golangci-lint-action@v3
         with:
-          version: v1.52
+          version: v1.61
 
   test:
     strategy:
       matrix:
-        go-version: [ '1.20', '1.21' ]
+        go-version: [ '1.21', '1.22', '1.23' ]
         platform: [ 'ubuntu-latest' ]
     runs-on: ${{ matrix.platform }}
     steps:
@@ -48,7 +48,7 @@ jobs:
         if: success()
         uses: actions/setup-go@v4
         with:
-          go-version: '1.20'
+          go-version: '1.23'
       - name: Calc coverage
         run: |
           go test -cover ./... -coverpkg=github.com/networkteam/construct/v2/... -coverprofile=coverage.txt

constructsql/constructsql.go

@@ -10,12 +10,14 @@ import (
 )
 
 // CollectRows collects all rows to the given target type from a ExecutiveQueryBuilder.Query result.
-func CollectRows[T any](rows Rows, err error) ([]T, error) {
-	if err != nil {
-		return nil, err
+func CollectRows[T any](rows Rows, queryErr error) (result []T, err error) {
+	if queryErr != nil {
+		return nil, queryErr
 	}
 
-	defer rows.Close()
+	defer func() {
+		err = errors.Join(err, rows.Close())
+	}()
 
 	slice := []T{}
 

constructsql/constructsql_iterator.go

@@ -0,0 +1,55 @@
+//go:build go1.23
+
+package constructsql
+
+import (
+	"errors"
+	"iter"
+	"log"
+)
+
+// IterateRows returns an iterator over the rows of a database query and scans them to T.
+// It returns a single-use iterator.
+func IterateRows[T any](rows Rows, err error) iter.Seq2[T, error] {
+	if err != nil {
+		return func(yield func(T, error) bool) {
+			var result T
+			yield(result, err)
+		}
+	}
+
+	return func(yield func(T, error) bool) {
+		var err error
+		var iteratorClosed bool
+
+		defer func() {
+			closeErr := rows.Close()
+			if iteratorClosed && closeErr != nil {
+				log.Printf("constructsql: Error closing rows after function for loop body returned false: %v", closeErr)
+				return
+			}
+
+			err = errors.Join(err, closeErr)
+			if err != nil {
+				var result T
+				yield(result, err)
+			}
+		}()
+
+		var value T
+		for rows.Next() {
+			value, err = scanRow[T](rows)
+			if err != nil {
+				return
+			}
+			if !yield(value, nil) {
+				iteratorClosed = true
+				return
+			}
+		}
+
+		if err = rows.Err(); err != nil {
+			return
+		}
+	}
+}

constructsql/constructsql_iterator_test.go

@@ -0,0 +1,258 @@
+//go:build go1.23
+
+package constructsql_test
+
+import (
+	"errors"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"github.com/networkteam/construct/v2/constructsql"
+)
+
+func TestIterateRows(t *testing.T) {
+	t.Run("iterate rows without error", func(t *testing.T) {
+		rows := mockRows{
+			rows: []mockRow{
+				{
+					scanJSON: []byte(`{"id": 1, "name": "test"}`),
+				},
+			},
+		}
+
+		count := 0
+		for record, err := range constructsql.IterateRows[user](&rows, nil) {
+			require.NoError(t, err)
+			assert.Equal(t, user{ID: 1, Name: "test"}, record)
+			count++
+		}
+		assert.Equal(t, 1, count)
+
+		assert.True(t, rows.closed)
+	})
+
+	t.Run("iterate empty rows without error", func(t *testing.T) {
+		rows := mockRows{
+			rows: []mockRow{},
+		}
+
+		count := 0
+		for range constructsql.IterateRows[user](&rows, nil) {
+			count++
+		}
+		assert.Equal(t, 0, count)
+
+		assert.True(t, rows.closed)
+	})
+
+	t.Run("iterate rows with early break", func(t *testing.T) {
+		rows := mockRows{
+			rows: []mockRow{
+				{
+					scanJSON: []byte(`{"id": 1, "name": "test"}`),
+				},
+				{
+					scanJSON: []byte(`{"id": 2, "name": "test"}`),
+				},
+			},
+		}
+
+		count := 0
+		for record, err := range constructsql.IterateRows[user](&rows, nil) {
+			if count == 0 {
+				require.NoError(t, err)
+				assert.Equal(t, user{ID: 1, Name: "test"}, record)
+			} else {
+				break
+			}
+			count++
+		}
+		assert.Equal(t, 1, count)
+
+		assert.True(t, rows.closed)
+	})
+
+	t.Run("iterate rows with early break and close error", func(t *testing.T) {
+		closeErr := errors.New("some error on close")
+		rows := mockRows{
+			rows: []mockRow{
+				{
+					scanJSON: []byte(`{"id": 1, "name": "test"}`),
+				},
+				{
+					scanJSON: []byte(`{"id": 2, "name": "test"}`),
+				},
+			},
+			closeErr: closeErr,
+		}
+
+		count := 0
+		for record, err := range constructsql.IterateRows[user](&rows, nil) {
+			if count == 0 {
+				require.NoError(t, err)
+				assert.Equal(t, user{ID: 1, Name: "test"}, record)
+			} else {
+				break
+			}
+			count++
+		}
+		assert.Equal(t, 1, count)
+
+		assert.True(t, rows.closed)
+	})
+
+	t.Run("iterate rows with initial error", func(t *testing.T) {
+		rows := mockRows{}
+		initialErr := errors.New("some initial error")
+		count := 0
+		for _, err := range constructsql.IterateRows[user](&rows, initialErr) {
+			assert.ErrorIs(t, err, initialErr)
+			count++
+		}
+		assert.Equal(t, 1, count)
+
+		assert.False(t, rows.closed)
+	})
+
+	t.Run("iterate rows with scan error", func(t *testing.T) {
+		scanErr := errors.New("some scan error")
+		rows := mockRows{
+			rows: []mockRow{
+				{
+					scanJSON: []byte(`{"id": 1, "name": "test"}`),
+				},
+				{
+					scanErr: scanErr,
+				},
+			},
+		}
+
+		count := 0
+		for record, err := range constructsql.IterateRows[user](&rows, nil) {
+			if count == 0 {
+				require.NoError(t, err)
+				assert.Equal(t, user{ID: 1, Name: "test"}, record)
+			} else if count == 1 {
+				assert.ErrorIs(t, err, scanErr)
+			}
+			count++
+		}
+		assert.Equal(t, 2, count)
+
+		assert.True(t, rows.closed)
+	})
+
+	t.Run("iterate rows with iterate error", func(t *testing.T) {
+		iterateErr := errors.New("some iterate error")
+		rows := mockRows{
+			rows: []mockRow{
+				{
+					scanJSON: []byte(`{"id": 1, "name": "test"}`),
+				},
+			},
+			iterateErr: iterateErr,
+		}
+
+		count := 0
+		for record, err := range constructsql.IterateRows[user](&rows, nil) {
+			if count == 0 {
+				require.NoError(t, err)
+				assert.Equal(t, user{ID: 1, Name: "test"}, record)
+			} else if count == 1 {
+				assert.ErrorIs(t, err, iterateErr)
+			}
+			count++
+		}
+		assert.Equal(t, 2, count)
+
+		assert.True(t, rows.closed)
+	})
+
+	t.Run("iterate rows with close error", func(t *testing.T) {
+		closeErr := errors.New("some error on close")
+		rows := mockRows{
+			rows: []mockRow{
+				{
+					scanJSON: []byte(`{"id": 1, "name": "test"}`),
+				},
+			},
+			closeErr: closeErr,
+		}
+
+		count := 0
+		for record, err := range constructsql.IterateRows[user](&rows, nil) {
+			if count == 0 {
+				require.NoError(t, err)
+				assert.Equal(t, user{ID: 1, Name: "test"}, record)
+			} else if count == 1 {
+				assert.ErrorIs(t, err, closeErr)
+			}
+			count++
+		}
+		assert.Equal(t, 2, count)
+
+		assert.True(t, rows.closed)
+	})
+
+	t.Run("iterate rows with scan and close error", func(t *testing.T) {
+		scanErr := errors.New("some scan error")
+		closeErr := errors.New("some error on close")
+		rows := mockRows{
+			rows: []mockRow{
+				{
+					scanJSON: []byte(`{"id": 1, "name": "test"}`),
+				},
+				{
+					scanErr: scanErr,
+				},
+			},
+			closeErr: closeErr,
+		}
+
+		count := 0
+		for record, err := range constructsql.IterateRows[user](&rows, nil) {
+			if count == 0 {
+				require.NoError(t, err)
+				assert.Equal(t, user{ID: 1, Name: "test"}, record)
+			} else if count == 1 {
+				assert.ErrorIs(t, err, scanErr)
+				assert.ErrorIs(t, err, closeErr)
+			}
+			count++
+		}
+		assert.Equal(t, 2, count)
+
+		assert.True(t, rows.closed)
+	})
+
+	t.Run("iterate rows with iterate and close error", func(t *testing.T) {
+		iterateErr := errors.New("some iterate error")
+		closeErr := errors.New("some error on close")
+		rows := mockRows{
+			rows: []mockRow{
+				{
+					scanJSON: []byte(`{"id": 1, "name": "test"}`),
+				},
+			},
+			iterateErr: iterateErr,
+			closeErr:   closeErr,
+		}
+
+		count := 0
+		for record, err := range constructsql.IterateRows[user](&rows, nil) {
+			if count == 0 {
+				require.NoError(t, err)
+				assert.Equal(t, user{ID: 1, Name: "test"}, record)
+			} else if count == 1 {
+				assert.ErrorIs(t, err, iterateErr)
+				assert.ErrorIs(t, err, closeErr)
+			}
+			count++
+		}
+		assert.Equal(t, 2, count)
+
+		assert.True(t, rows.closed)
+	})
+}