added len method

test/benchmarks_test.go

@@ -87,7 +87,7 @@ func BenchmarkV1BulkInsert100KDocs(b *testing.B) {
 }
 
 func bulkRead(b *testing.B, docSize int) {
-	db, col := setup(b)
+	_, col := setup(b)
 
 	// -----------------------------
 	// Prepare and insert documents
@@ -110,31 +110,24 @@ func bulkRead(b *testing.B, docSize int) {
 	require.NoError(b, err)
 
 	// -----------------------------------------
-	// Sub-benchmark 1: Read entire collection
+	// Sub-benchmark 1: Read entire collection using ReadDocuments
 	// -----------------------------------------
 	b.Run("ReadAllDocsOnce", func(b *testing.B) {
-		query := fmt.Sprintf("FOR d IN %s RETURN d", col.Name())
+		// Prepare keys for reading
+		keys := make([]string, docSize)
+		for j := 0; j < docSize; j++ {
+			keys[j] = fmt.Sprintf("doc_%d", j)
+		}
 
 		b.ResetTimer()
 		for i := 0; i < b.N; i++ {
-			cursor, err := db.Query(ctx, query, nil)
+			readDocs := make([]TestDoc, docSize)
+			_, _, err := col.ReadDocuments(ctx, keys, readDocs)
 			require.NoError(b, err)
 
-			count := 0
-			for {
-				var doc TestDoc
-				_, err := cursor.ReadDocument(ctx, &doc)
-				if driver.IsNoMoreDocuments(err) {
-					break
-				}
-				require.NoError(b, err)
-				count++
-			}
-			// require.Equal(b, docSize, count, "expected to read all documents")
-			_ = cursor.Close()
 			// sanity check
-			if count != docSize {
-				b.Fatalf("expected to read %d docs, got %d", docSize, count)
+			if len(readDocs) != docSize {
+				b.Fatalf("expected to read %d docs, got %d", docSize, len(readDocs))
 			}
 		}
 	})

v2/CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ## [master](https://github.com/arangodb/go-driver/tree/master) (N/A)
 - Add endpoint to fetch deployment id
+- Add len() for Read methods
 
 ## [2.1.6](https://github.com/arangodb/go-driver/tree/v2.1.6) (2025-11-06)
 - Add missing endpoints from replication

v2/arangodb/collection_documents_create.go

@@ -71,7 +71,9 @@ type CollectionDocumentCreate interface {
 }
 
 type CollectionDocumentCreateResponseReader interface {
+	shared.ReadAllReadable[CollectionDocumentCreateResponse]
 	Read() (CollectionDocumentCreateResponse, error)
+	Len() int
 }
 
 type CollectionDocumentCreateResponse struct {

v2/arangodb/collection_documents_create_impl.go

@@ -24,6 +24,7 @@ import (
 	"context"
 	"io"
 	"net/http"
+	"reflect"
 
 	"github.com/pkg/errors"
 
@@ -129,10 +130,19 @@ func newCollectionDocumentCreateResponseReader(array *connection.Array, options
 	c := &collectionDocumentCreateResponseReader{array: array, options: options}
 
 	if c.options != nil {
+		// Cache reflection types once during initialization for performance
+		if c.options.OldObject != nil {
+			c.oldType = reflect.TypeOf(c.options.OldObject).Elem()
+		}
+		if c.options.NewObject != nil {
+			c.newType = reflect.TypeOf(c.options.NewObject).Elem()
+		}
+
 		c.response.Old = newUnmarshalInto(c.options.OldObject)
 		c.response.New = newUnmarshalInto(c.options.NewObject)
 	}
 
+	c.ReadAllReader = shared.ReadAllReader[CollectionDocumentCreateResponse, *collectionDocumentCreateResponseReader]{Reader: c}
 	return c
 }
 
@@ -147,22 +157,51 @@ type collectionDocumentCreateResponseReader struct {
 		Old                    *UnmarshalInto `json:"old,omitempty"`
 		New                    *UnmarshalInto `json:"new,omitempty"`
 	}
+	shared.ReadAllReader[CollectionDocumentCreateResponse, *collectionDocumentCreateResponseReader]
+
+	// Cache for len() method - allows Read() to work after Len() is called
+	cachedResults []CollectionDocumentCreateResponse
+	cachedErrors  []error
+	cached        bool
+	readIndex     int // Track position in cache for Read() after Len()
+
+	// Performance: Cache reflection types to avoid repeated lookups
+	oldType reflect.Type
+	newType reflect.Type
 }
 
 func (c *collectionDocumentCreateResponseReader) Read() (CollectionDocumentCreateResponse, error) {
+	// If Len() was called, serve from cache
+	if c.cached {
+		if c.readIndex >= len(c.cachedResults) {
+			return CollectionDocumentCreateResponse{}, shared.NoMoreDocumentsError{}
+		}
+		result := c.cachedResults[c.readIndex]
+		err := c.cachedErrors[c.readIndex]
+		c.readIndex++
+		return result, err
+	}
+
+	// Normal streaming read
 	if !c.array.More() {
 		return CollectionDocumentCreateResponse{}, shared.NoMoreDocumentsError{}
 	}
 
 	var meta CollectionDocumentCreateResponse
 
-	if c.options != nil {
-		meta.Old = c.options.OldObject
-		meta.New = c.options.NewObject
+	// Create new instances for each document to avoid pointer reuse
+	// Use cached types for performance
+	if c.oldType != nil {
+		meta.Old = reflect.New(c.oldType).Interface()
+	}
+	if c.newType != nil {
+		meta.New = reflect.New(c.newType).Interface()
 	}
 
 	c.response.DocumentMeta = &meta.DocumentMeta
 	c.response.ResponseStruct = &meta.ResponseStruct
+	c.response.Old = newUnmarshalInto(meta.Old)
+	c.response.New = newUnmarshalInto(meta.New)
 
 	if err := c.array.Unmarshal(&c.response); err != nil {
 		if err == io.EOF {
@@ -175,5 +214,30 @@ func (c *collectionDocumentCreateResponseReader) Read() (CollectionDocumentCreat
 		return meta, meta.AsArangoError()
 	}
 
+	// Copy data from the new instances back to the original option objects for backward compatibility
+	if c.options != nil {
+		if c.options.OldObject != nil && meta.Old != nil {
+			oldValue := reflect.ValueOf(meta.Old).Elem()
+			originalValue := reflect.ValueOf(c.options.OldObject).Elem()
+			originalValue.Set(oldValue)
+		}
+		if c.options.NewObject != nil && meta.New != nil {
+			newValue := reflect.ValueOf(meta.New).Elem()
+			originalValue := reflect.ValueOf(c.options.NewObject).Elem()
+			originalValue.Set(newValue)
+		}
+	}
+
 	return meta, nil
 }
+
+// Len returns the number of items in the response.
+// After calling Len(), you can still use Read() to iterate through items.
+func (c *collectionDocumentCreateResponseReader) Len() int {
+	if !c.cached {
+		c.cachedResults, c.cachedErrors = c.ReadAll()
+		c.cached = true
+		c.readIndex = 0 // Reset read position to allow Read() after Len()
+	}
+	return len(c.cachedResults)
+}

v2/arangodb/collection_documents_delete.go

@@ -63,7 +63,9 @@ type CollectionDocumentDeleteResponse struct {
 }
 
 type CollectionDocumentDeleteResponseReader interface {
+	shared.ReadAllIntoReadable[CollectionDocumentDeleteResponse]
 	Read(i interface{}) (CollectionDocumentDeleteResponse, error)
+	Len() int
 }
 
 type CollectionDocumentDeleteOptions struct {
@@ -82,6 +84,7 @@ type CollectionDocumentDeleteOptions struct {
 	WithWaitForSync *bool
 
 	// Return additionally the complete previous revision of the changed document
+	// Should be a pointer to an object
 	OldObject interface{}
 
 	// If set to true, an empty object is returned as response if the document operation succeeds.

v2/arangodb/collection_documents_delete_impl.go

@@ -24,6 +24,7 @@ import (
 	"context"
 	"io"
 	"net/http"
+	"reflect"
 
 	"github.com/pkg/errors"
 
@@ -42,6 +43,7 @@ var _ CollectionDocumentDelete = &collectionDocumentDelete{}
 
 type collectionDocumentDelete struct {
 	collection *collection
+	shared.ReadAllIntoReader[CollectionDocumentDeleteResponse, *collectionDocumentDeleteResponseReader]
 }
 
 func (c collectionDocumentDelete) DeleteDocument(ctx context.Context, key string) (CollectionDocumentDeleteResponse, error) {
@@ -103,6 +105,7 @@ func (c collectionDocumentDelete) DeleteDocumentsWithOptions(ctx context.Context
 func newCollectionDocumentDeleteResponseReader(array *connection.Array, options *CollectionDocumentDeleteOptions) *collectionDocumentDeleteResponseReader {
 	c := &collectionDocumentDeleteResponseReader{array: array, options: options}
 
+	c.ReadAllIntoReader = shared.ReadAllIntoReader[CollectionDocumentDeleteResponse, *collectionDocumentDeleteResponseReader]{Reader: c}
 	return c
 }
 
@@ -111,9 +114,28 @@ var _ CollectionDocumentDeleteResponseReader = &collectionDocumentDeleteResponse
 type collectionDocumentDeleteResponseReader struct {
 	array   *connection.Array
 	options *CollectionDocumentDeleteOptions
+	shared.ReadAllIntoReader[CollectionDocumentDeleteResponse, *collectionDocumentDeleteResponseReader]
+	// Cache for len() method - allows Read() to work after Len() is called
+	cachedResults []CollectionDocumentDeleteResponse
+	cachedErrors  []error
+	cached        bool
+	readIndex     int // Track position in cache for Read() after Len()
 }
 
 func (c *collectionDocumentDeleteResponseReader) Read(i interface{}) (CollectionDocumentDeleteResponse, error) {
+	// If Len() was called, serve from cache
+	// Note: When serving from cache, the 'i' parameter is not populated with document data
+	if c.cached {
+		if c.readIndex >= len(c.cachedResults) {
+			return CollectionDocumentDeleteResponse{}, shared.NoMoreDocumentsError{}
+		}
+		result := c.cachedResults[c.readIndex]
+		err := c.cachedErrors[c.readIndex]
+		c.readIndex++
+		return result, err
+	}
+
+	// Normal streaming read
 	if !c.array.More() {
 		return CollectionDocumentDeleteResponse{}, shared.NoMoreDocumentsError{}
 	}
@@ -146,11 +168,33 @@ func (c *collectionDocumentDeleteResponseReader) Read(i interface{}) (Collection
 	}
 
 	if c.options != nil && c.options.OldObject != nil {
-		meta.Old = c.options.OldObject
+		// Create a new instance for each document to avoid reusing the same pointer
+		oldObjectType := reflect.TypeOf(c.options.OldObject).Elem()
+		meta.Old = reflect.New(oldObjectType).Interface()
+
+		// Extract old data into the new instance
 		if err := response.Object.Object.Extract("old").Inject(meta.Old); err != nil {
 			return CollectionDocumentDeleteResponse{}, err
 		}
+
+		// Copy data from the new instance to the original OldObject for backward compatibility
+		oldValue := reflect.ValueOf(meta.Old).Elem()
+		originalValue := reflect.ValueOf(c.options.OldObject).Elem()
+		originalValue.Set(oldValue)
 	}
 
 	return meta, nil
 }
+
+// Len returns the number of items in the response.
+// After calling Len(), you can still use Read() to iterate through items.
+// Note: When Read() serves from cache, the document data parameter is not populated.
+func (c *collectionDocumentDeleteResponseReader) Len() int {
+	if !c.cached {
+		var dummySlice []interface{}
+		c.cachedResults, c.cachedErrors = c.ReadAll(&dummySlice)
+		c.cached = true
+		c.readIndex = 0 // Reset read position to allow Read() after Len()
+	}
+	return len(c.cachedResults)
+}

v2/arangodb/collection_documents_read.go

@@ -59,6 +59,8 @@ type CollectionDocumentRead interface {
 
 type CollectionDocumentReadResponseReader interface {
 	Read(i interface{}) (CollectionDocumentReadResponse, error)
+	shared.ReadAllIntoReadable[CollectionDocumentReadResponse]
+	Len() int
 }
 
 type CollectionDocumentReadResponse struct {

v2/arangodb/collection_documents_read_impl.go

@@ -97,7 +97,7 @@ func (c collectionDocumentRead) ReadDocumentWithOptions(ctx context.Context, key
 
 func newCollectionDocumentReadResponseReader(array *connection.Array, options *CollectionDocumentReadOptions) *collectionDocumentReadResponseReader {
 	c := &collectionDocumentReadResponseReader{array: array, options: options}
-
+	c.ReadAllIntoReader = shared.ReadAllIntoReader[CollectionDocumentReadResponse, *collectionDocumentReadResponseReader]{Reader: c}
 	return c
 }
 
@@ -106,9 +106,28 @@ var _ CollectionDocumentReadResponseReader = &collectionDocumentReadResponseRead
 type collectionDocumentReadResponseReader struct {
 	array   *connection.Array
 	options *CollectionDocumentReadOptions
+	shared.ReadAllIntoReader[CollectionDocumentReadResponse, *collectionDocumentReadResponseReader]
+	// Cache for len() method - allows Read() to work after Len() is called
+	cachedResults []CollectionDocumentReadResponse
+	cachedErrors  []error
+	cached        bool
+	readIndex     int // Track position in cache for Read() after Len()
 }
 
 func (c *collectionDocumentReadResponseReader) Read(i interface{}) (CollectionDocumentReadResponse, error) {
+	// If Len() was called, serve from cache
+	// Note: When serving from cache, the 'i' parameter is not populated with document data
+	if c.cached {
+		if c.readIndex >= len(c.cachedResults) {
+			return CollectionDocumentReadResponse{}, shared.NoMoreDocumentsError{}
+		}
+		result := c.cachedResults[c.readIndex]
+		err := c.cachedErrors[c.readIndex]
+		c.readIndex++
+		return result, err
+	}
+
+	// Normal streaming read
 	if !c.array.More() {
 		return CollectionDocumentReadResponse{}, shared.NoMoreDocumentsError{}
 	}
@@ -142,3 +161,16 @@ func (c *collectionDocumentReadResponseReader) Read(i interface{}) (CollectionDo
 
 	return meta, nil
 }
+
+// Len returns the number of items in the response.
+// After calling Len(), you can still use Read() to iterate through items.
+// Note: When Read() serves from cache, the document data parameter is not populated.
+func (c *collectionDocumentReadResponseReader) Len() int {
+	if !c.cached {
+		var dummySlice []interface{}
+		c.cachedResults, c.cachedErrors = c.ReadAll(&dummySlice)
+		c.cached = true
+		c.readIndex = 0 // Reset read position to allow Read() after Len()
+	}
+	return len(c.cachedResults)
+}

v2/arangodb/collection_documents_replace.go

@@ -61,7 +61,9 @@ type CollectionDocumentReplace interface {
 }
 
 type CollectionDocumentReplaceResponseReader interface {
+	shared.ReadAllReadable[CollectionDocumentReplaceResponse]
 	Read() (CollectionDocumentReplaceResponse, error)
+	Len() int
 }
 
 type CollectionDocumentReplaceResponse struct {