Added Increment and Decrement methods for Number fields.

README.md

@@ -12,14 +12,14 @@ It does not do anything crazy or magic – the purpose is to reduce the amount o
 ## Context
 While working on a project running on multiple services and serverless functions, I quickly realised that the amount of repetitive and boilerplate code related to Firestore increased exponentially.
 
-I decided to extract this code in a thin and layer on top of the Firestore admin client. That's how fuego came to life.
+I decided to extract this code in a thin layer on top of the Firestore admin client. That's how fuego came to life.
 
 ![Fuego](https://raw.githubusercontent.com/remychantenay/fuego/master/art/fuego.jpg)
 
 ## Features
 ### Documents
 * CRUD operations
-* Retrieving specific fields only
+* Retrieving/Updating specific fields only
 * Simple Exists check
 
 ### Collections

document/array.go

@@ -52,7 +52,7 @@ func (a *Array) Override(ctx context.Context, data []interface{}) error {
 
 // Append will append the provided data to the existing data (if any) of an Array field.
 //
-// The update will be done inside a transaction as we need to read the value beforehand.
+// The update will be executed inside a transaction.
 //  values, err := fuego.Document("users", "jsmith").Array("Address").Append(ctx, []interface{}{"More info"})
 func (a *Array) Append(ctx context.Context, data []interface{}) error {
 

document/document.go

@@ -9,9 +9,6 @@ import (
 // Document provides the necessary to interact with a Firestore document.
 type Document interface {
 
-	// GetDocumentRef returns a Document Reference (DocumentRef).
-	GetDocumentRef() *firestore.DocumentRef
-
 	// Create a document.
 	Create(ctx context.Context, from interface{}) error
 
@@ -45,6 +42,15 @@ type Document interface {
 
 	// Timestamp returns a specific Timestamp field.
 	Timestamp(name string) *Timestamp
+
+	// GetDocumentRef returns a Document Reference (DocumentRef).
+	GetDocumentRef() *firestore.DocumentRef
+
+	// InBatch returns true if a WriteBatch has been started, false otherwise.
+	InBatch() bool
+
+	// Batch returns the pointer to the WriteBatch (if any), nil oherwise.
+	Batch() *firestore.WriteBatch
 }
 
 // FirestoreDocument provides features related to Firestore documents.
@@ -56,16 +62,20 @@ type FirestoreDocument struct {
 	// ID is the ID of the document
 	ID string
 
+	// writeBatch will be nil if not started with fuego.StartBatch() or cancelled with fuego.CancelBatch().
+	writeBatch *firestore.WriteBatch
+
 	firestore *firestore.Client
 }
 
 // New creates and returns a new FirestoreDocument.
-func New(fs *firestore.Client, path, documentID string) *FirestoreDocument {
+func New(fs *firestore.Client, path, documentID string, wb *firestore.WriteBatch) *FirestoreDocument {
 	r := fs.Collection(path)
 	return &FirestoreDocument{
-		ColRef:    r,
-		ID:        documentID,
-		firestore: fs,
+		ColRef:     r,
+		ID:         documentID,
+		firestore:  fs,
+		writeBatch: wb,
 	}
 }
 
@@ -81,7 +91,12 @@ func (d *FirestoreDocument) GetDocumentRef() *firestore.DocumentRef {
 
 // Create a document in Firestore.
 func (d *FirestoreDocument) Create(ctx context.Context, from interface{}) error {
-	_, err := d.GetDocumentRef().Set(ctx, from)
+	ref := d.GetDocumentRef()
+	if d.InBatch() {
+		d.Batch().Set(ref, from)
+		return nil
+	}
+	_, err := ref.Set(ctx, from)
 	return err
 }
 
@@ -117,7 +132,12 @@ func (d *FirestoreDocument) Exists(ctx context.Context) bool {
 
 // Delete removes a document from Firestore.
 func (d *FirestoreDocument) Delete(ctx context.Context) error {
-	_, err := d.GetDocumentRef().Delete(ctx)
+	ref := d.GetDocumentRef()
+	if d.InBatch() {
+		d.Batch().Delete(ref)
+		return nil
+	}
+	_, err := ref.Delete(ctx)
 	if err != nil {
 		return err
 	}
@@ -145,8 +165,9 @@ func (d *FirestoreDocument) String(name string) *String {
 // Number returns a new Number.
 func (d *FirestoreDocument) Number(name string) *Number {
 	return &Number{
-		Document: d,
-		Name:     name,
+		Document:  d,
+		Name:      name,
+		firestore: d.firestore,
 	}
 }
 
@@ -174,3 +195,13 @@ func (d *FirestoreDocument) Timestamp(name string) *Timestamp {
 		Name:     name,
 	}
 }
+
+// InBatch returns true if a WriteBatch has been started, false otherwise.
+func (d *FirestoreDocument) InBatch() bool {
+	return d.writeBatch != nil
+}
+
+// Batch returns the pointer to the WriteBatch (if any), nil oherwise.
+func (d *FirestoreDocument) Batch() *firestore.WriteBatch {
+	return d.writeBatch
+}

document/number.go

@@ -12,14 +12,24 @@ type NumberField interface {
 	// Retrieve returns the value of a specific field containing a number (int64).
 	Retrieve(ctx context.Context) (int64, error)
 
-	// Update updates the value of a specific field containing a number (int64).
+	// Update the value of a specific field containing a number (int64).
 	Update(ctx context.Context, with int64) error
+
+	// Increment the value of a specific field containing a number (int64).
+	// If the field doesn't exist, it will be set to 1.
+	Increment(ctx context.Context) error
+
+	// Decrement the value of a specific field containing a number (int64).
+	// If the field doesn't exist, it will be set to 0.
+	Decrement(ctx context.Context) error
 }
 
 // Number represents a document field of type Number.
 type Number struct {
 	Document Document
 	Name     string
+
+	firestore *firestore.Client
 }
 
 // Retrieve returns the content of a specific field for a given document.
@@ -33,12 +43,76 @@ func (n *Number) Retrieve(ctx context.Context) (int64, error) {
 	return value.(int64), nil
 }
 
-// Update updates the value of a specific field of type Number.
-//  err := fuego.Document("users", "jsmith").Number("Age").Update(ctx, 42)
+// Update the value of a specific field of type Number.
+//  err := fuego.Document("users", "jsmith").Number("Age").Update(ctx, 42).
 func (n *Number) Update(ctx context.Context, with int64) error {
 
 	_, err := n.Document.GetDocumentRef().Set(ctx, map[string]int64{
 		n.Name: with,
 	}, firestore.MergeAll)
 	return err
 }
+
+// Increment the value of a specific field of type Number.
+//
+// The update will be executed inside a transaction.
+// If the field doesn't exist, it will be set to 1.
+//  err := fuego.Document("users", "jsmith").Number("Age").Increment(ctx)
+func (n *Number) Increment(ctx context.Context) error {
+
+	return n.firestore.RunTransaction(ctx, func(ctx context.Context, tx *firestore.Transaction) error {
+
+		ref := n.Document.GetDocumentRef()
+		document, err := tx.Get(ref)
+		if err != nil {
+			return err
+		}
+
+		newValue := int64(1)
+		value, err := document.DataAt(n.Name)
+		if err == nil {
+			newValue = value.(int64) + 1
+		}
+
+		err = tx.Set(ref, map[string]int64{
+			n.Name: newValue,
+		}, firestore.MergeAll)
+		if err != nil {
+			return err
+		}
+
+		return nil // Success, no errors
+	})
+}
+
+// Decrement the value of a specific field of type Number.
+//
+// The update will be executed inside a transaction.
+// If the field doesn't exist, it will be set to 0.
+//  err := fuego.Document("users", "jsmith").Number("Age").Decrement(ctx)
+func (n *Number) Decrement(ctx context.Context) error {
+
+	return n.firestore.RunTransaction(ctx, func(ctx context.Context, tx *firestore.Transaction) error {
+
+		ref := n.Document.GetDocumentRef()
+		document, err := tx.Get(ref)
+		if err != nil {
+			return err
+		}
+
+		newValue := int64(0)
+		value, err := document.DataAt(n.Name)
+		if err == nil {
+			newValue = value.(int64) - 1
+		}
+
+		err = tx.Set(ref, map[string]int64{
+			n.Name: newValue,
+		}, firestore.MergeAll)
+		if err != nil {
+			return err
+		}
+
+		return nil // Success, no errors
+	})
+}

errors.go

@@ -0,0 +1,8 @@
+package fuego
+
+import "errors"
+
+var (
+	// ErrBatchWriteNotStarted indicates that the a commit can't happen if the batch write hasn't been started.
+	ErrBatchWriteNotStarted = errors.New("fuego: no batch write started")
+)

fuego.go

@@ -2,29 +2,56 @@ package fuego
 
 import (
 	"cloud.google.com/go/firestore"
+	"context"
 	"github.com/remychantenay/fuego/collection"
 	"github.com/remychantenay/fuego/document"
 	"strings"
 )
 
-// Fuego is a wrapper for the Firestore client
-// It contains the Firestore client
+// Fuego is a wrapper for the Firestore client.
+// Contains the Firestore client.
 type Fuego struct {
-	firestore *firestore.Client
+
+	// FirestoreClient is a ptr to a firestore client.
+	FirestoreClient *firestore.Client
+
+	// WriteBatch is a ptr to a writebatch.
+	// will be nil if not started with StartBatch() or cancelled with CancelBatch().
+	WriteBatch *firestore.WriteBatch
 }
 
-// New creates and returns a Fuego wrapper
-func New(fc *firestore.Client) *Fuego {
+// New creates and returns a Fuego wrapper.
+func New(fs *firestore.Client) *Fuego {
 	return &Fuego{
-		firestore: fc,
+		FirestoreClient: fs,
+		WriteBatch:      nil,
 	}
 }
 
+// StartBatch starts a write batch.
+// Write operations that follow will be added to the batch and processed when CommitBatch is called.
+func (f *Fuego) StartBatch() {
+	f.WriteBatch = f.FirestoreClient.Batch()
+}
+
+// CommitBatch commits the write batch previously started with StartBatch().
+func (f *Fuego) CommitBatch(ctx context.Context) ([]*firestore.WriteResult, error) {
+	if f.WriteBatch == nil {
+		return nil, ErrBatchWriteNotStarted
+	}
+	return f.WriteBatch.Commit(ctx)
+}
+
+// CancelBatch cancels an on-going write batch (if any).
+func (f *Fuego) CancelBatch() {
+	f.WriteBatch = nil
+}
+
 // Document returns a new FirestoreDocument.
 func (f *Fuego) Document(path, documentID string) *document.FirestoreDocument {
 	path = strings.TrimPrefix(path, "/")
 	path = strings.TrimSuffix(path, "/")
-	return document.New(f.firestore, path, documentID)
+	return document.New(f.FirestoreClient, path, documentID, f.WriteBatch)
 }
 
 // DocumentWithGeneratedID returns a new FirestoreDocument without ID.
@@ -36,5 +63,5 @@ func (f *Fuego) DocumentWithGeneratedID(path string) *document.FirestoreDocument
 func (f *Fuego) Collection(path string) *collection.FirestoreCollection {
 	path = strings.TrimPrefix(path, "/")
 	path = strings.TrimSuffix(path, "/")
-	return collection.New(f.firestore, path)
+	return collection.New(f.FirestoreClient, path)
 }

integration_test.go

@@ -274,6 +274,58 @@ func TestIntegration_Number_Update(t *testing.T) {
 	fmt.Println("New Age: ", value)
 }
 
+func TestIntegration_Number_Increment(t *testing.T) {
+	ctx := context.Background()
+
+	expectedNewValue := int64(32)
+
+	err := fuego.Document("users", "jsmith").
+		Number("Age").
+		Increment(ctx)
+	if err != nil {
+		t.Fatalf(err.Error())
+	}
+
+	value, err := fuego.Document("users", "jsmith").
+		Number("Age").
+		Retrieve(ctx)
+	if err != nil {
+		t.Fatalf(err.Error())
+	}
+
+	if value != expectedNewValue {
+		t.Fatalf("Got %d but expected %d", value, expectedNewValue)
+	}
+
+	fmt.Println("Incremented Age: ", value)
+}
+
+func TestIntegration_Number_Decrement(t *testing.T) {
+	ctx := context.Background()
+
+	expectedNewValue := int64(31)
+
+	err := fuego.Document("users", "jsmith").
+		Number("Age").
+		Decrement(ctx)
+	if err != nil {
+		t.Fatalf(err.Error())
+	}
+
+	value, err := fuego.Document("users", "jsmith").
+		Number("Age").
+		Retrieve(ctx)
+	if err != nil {
+		t.Fatalf(err.Error())
+	}
+
+	if value != expectedNewValue {
+		t.Fatalf("Got %d but expected %d", value, expectedNewValue)
+	}
+
+	fmt.Println("Decremented Age: ", value)
+}
+
 func TestIntegration_Timestamp_Retrieve(t *testing.T) {
 	ctx := context.Background()