import{runTransaction}from"firebase/firestore";try{awaitrunTransaction(db,async(transaction)=>{constsfDoc=awaittransaction.get(sfDocRef);if(!sfDoc.exists()){throw"Document does not exist!";}constnewPopulation=sfDoc.data().population+1;transaction.update(sfDocRef,{population:newPopulation});});console.log("Transaction successfully committed!");}catch(e){console.log("Transaction failed: ",e);}
transaction.js

// Create a reference to the SF doc.varsfDocRef=db.collection("cities").doc("SF");// Uncomment to initialize the doc.// sfDocRef.set({ population: 0 });returndb.runTransaction((transaction)=>{// This code may get re-run multiple times if there are conflicts.returntransaction.get(sfDocRef).then((sfDoc)=>{if(!sfDoc.exists){throw"Document does not exist!";}// Add one person to the city population.// Note: this could be done without a transaction//       by updating the population using FieldValue.increment()varnewPopulation=sfDoc.data().population+1;transaction.update(sfDocRef,{population:newPopulation});});}).then(()=>{console.log("Transaction successfully committed!");}).catch((error)=>{console.log("Transaction failed: ",error);});
test.firestore.js

letsfReference=db.collection("cities").document("SF")do{let_=tryawaitdb.runTransaction({(transaction,errorPointer)->Any?inletsfDocument:DocumentSnapshotdo{trysfDocument=transaction.getDocument(sfReference)}catchletfetchErrorasNSError{errorPointer?.pointee=fetchErrorreturnnil}guardletoldPopulation=sfDocument.data()?["population"]as?Intelse{leterror=NSError(domain:"AppErrorDomain",code:-1,userInfo:[NSLocalizedDescriptionKey:"Unable to retrieve population from snapshot\(sfDocument)"])errorPointer?.pointee=errorreturnnil}// Note: this could be done without a transaction//       by updating the population using FieldValue.increment()transaction.updateData(["population":oldPopulation+1],forDocument:sfReference)returnnil})print("Transaction successfully committed!")}catch{print("Transaction failed:\(error)")}
ViewController.swift

FIRDocumentReference*sfReference=[[self.dbcollectionWithPath:@"cities"]documentWithPath:@"SF"];[self.dbrunTransactionWithBlock:^id(FIRTransaction*transaction,NSError**errorPointer){FIRDocumentSnapshot*sfDocument=[transactiongetDocument:sfReferenceerror:errorPointer];if(*errorPointer!=nil){returnnil;}if(![sfDocument.data[@"population"]isKindOfClass:[NSNumberclass]]){*errorPointer=[NSErrorerrorWithDomain:@"AppErrorDomain"code:-1userInfo:@{NSLocalizedDescriptionKey:@"Unable to retreive population from snapshot"}];returnnil;}NSIntegeroldPopulation=[sfDocument.data[@"population"]integerValue];// Note: this could be done without a transaction//       by updating the population using FieldValue.increment()[transactionupdateData:@{@"population":@(oldPopulation+1)}forDocument:sfReference];returnnil;}completion:^(idresult,NSError*error){if(error!=nil){NSLog(@"Transaction failed: %@",error);}else{NSLog(@"Transaction successfully committed!");}}];
ViewController.m

valsfDocRef=db.collection("cities").document("SF")db.runTransaction{transaction->valsnapshot=transaction.get(sfDocRef)// Note: this could be done without a transaction//       by updating the population using FieldValue.increment()valnewPopulation=snapshot.getDouble("population")!!+1transaction.update(sfDocRef,"population",newPopulation)// Successnull}.addOnSuccessListener{Log.d(TAG,"Transaction success!")}.addOnFailureListener{e->Log.w(TAG,"Transaction failure.",e)}
DocSnippets.kt

finalDocumentReferencesfDocRef=db.collection("cities").document("SF");db.runTransaction(newTransaction.Function<Void>(){@OverridepublicVoidapply(@NonNullTransactiontransaction)throwsFirebaseFirestoreException{DocumentSnapshotsnapshot=transaction.get(sfDocRef);// Note: this could be done without a transaction//       by updating the population using FieldValue.increment()doublenewPopulation=snapshot.getDouble("population")+1;transaction.update(sfDocRef,"population",newPopulation);// Successreturnnull;}}).addOnSuccessListener(newOnSuccessListener<Void>(){@OverridepublicvoidonSuccess(VoidaVoid){Log.d(TAG,"Transaction success!");}}).addOnFailureListener(newOnFailureListener(){@OverridepublicvoidonFailure(@NonNullExceptione){Log.w(TAG,"Transaction failure.",e);}});
DocSnippets.java

finalsfDocRef=db.collection("cities").doc("SF");db.runTransaction((transaction)async{finalsnapshot=awaittransaction.get(sfDocRef);// Note: this could be done without a transaction//       by updating the population using FieldValue.increment()finalnewPopulation=snapshot.get("population")+1;transaction.update(sfDocRef,{"population":newPopulation});}).then((value)=>print("DocumentSnapshot successfully updated!"),onError:(e)=>print("Error updating document$e"),);
firestore.dart

DocumentReferencesf_doc_ref=db->Collection("cities").Document("SF");db->RunTransaction([sf_doc_ref](Transaction&transaction,std::string&out_error_message)->Error{Errorerror=Error::kErrorOk;DocumentSnapshotsnapshot=transaction.Get(sf_doc_ref,&error,&out_error_message);// Note: this could be done without a transaction by updating the// population using FieldValue::Increment().std::int64_tnew_population=snapshot.Get("population").integer_value()+1;transaction.Update(sf_doc_ref,{{"population", FieldValue::Integer(new_population)}});returnError::kErrorOk;}).OnCompletion([](constFuture<void>&future){if(future.error()==Error::kErrorOk){std::cout <<"Transaction success!" <<std::endl;}else{std::cout <<"Transaction failure: " <<future.error_message() <<std::endl;}});
snippets.cpp

DocumentReferencecityRef=db.Collection("cities").Document("SF");db.RunTransactionAsync(transaction=>{returntransaction.GetSnapshotAsync(cityRef).ContinueWith((snapshotTask)=>{DocumentSnapshotsnapshot=snapshotTask.Result;longnewPopulation=snapshot.GetValue<long>("Population")+1;Dictionary<string,object>updates=newDictionary<string,object>{{"Population",newPopulation}};transaction.Update(cityRef,updates);});});

import{doc,runTransaction}from"firebase/firestore";// Create a reference to the SF doc.constsfDocRef=doc(db,"cities","SF");try{constnewPopulation=awaitrunTransaction(db,async(transaction)=>{constsfDoc=awaittransaction.get(sfDocRef);if(!sfDoc.exists()){throw"Document does not exist!";}constnewPop=sfDoc.data().population+1;if(newPop<=1000000){transaction.update(sfDocRef,{population:newPop});returnnewPop;}else{returnPromise.reject("Sorry! Population is too big");}});console.log("Population increased to ",newPopulation);}catch(e){// This will be a "population is too big" error.console.error(e);}
transaction_promise.js

// Create a reference to the SF doc.varsfDocRef=db.collection("cities").doc("SF");db.runTransaction((transaction)=>{returntransaction.get(sfDocRef).then((sfDoc)=>{if(!sfDoc.exists){throw"Document does not exist!";}varnewPopulation=sfDoc.data().population+1;if(newPopulation<=1000000){transaction.update(sfDocRef,{population:newPopulation});returnnewPopulation;}else{returnPromise.reject("Sorry! Population is too big.");}});}).then((newPopulation)=>{console.log("Population increased to ",newPopulation);}).catch((err)=>{// This will be an "population is too big" error.console.error(err);});
test.firestore.js

letsfReference=db.collection("cities").document("SF")do{letobject=tryawaitdb.runTransaction({(transaction,errorPointer)->Any?inletsfDocument:DocumentSnapshotdo{trysfDocument=transaction.getDocument(sfReference)}catchletfetchErrorasNSError{errorPointer?.pointee=fetchErrorreturnnil}guardletoldPopulation=sfDocument.data()?["population"]as?Intelse{leterror=NSError(domain:"AppErrorDomain",code:-1,userInfo:[NSLocalizedDescriptionKey:"Unable to retrieve population from snapshot\(sfDocument)"])errorPointer?.pointee=errorreturnnil}// Note: this could be done without a transaction//       by updating the population using FieldValue.increment()letnewPopulation=oldPopulation+1guardnewPopulation<=1000000else{leterror=NSError(domain:"AppErrorDomain",code:-2,userInfo:[NSLocalizedDescriptionKey:"Population\(newPopulation) too big"])errorPointer?.pointee=errorreturnnil}transaction.updateData(["population":newPopulation],forDocument:sfReference)returnnewPopulation})print("Population increased to\(object!)")}catch{print("Error updating population:\(error)")}
ViewController.swift

FIRDocumentReference*sfReference=[[self.dbcollectionWithPath:@"cities"]documentWithPath:@"SF"];[self.dbrunTransactionWithBlock:^id(FIRTransaction*transaction,NSError**errorPointer){FIRDocumentSnapshot*sfDocument=[transactiongetDocument:sfReferenceerror:errorPointer];if(*errorPointer!=nil){returnnil;}if(![sfDocument.data[@"population"]isKindOfClass:[NSNumberclass]]){*errorPointer=[NSErrorerrorWithDomain:@"AppErrorDomain"code:-1userInfo:@{NSLocalizedDescriptionKey:@"Unable to retreive population from snapshot"}];returnnil;}NSIntegerpopulation=[sfDocument.data[@"population"]integerValue];population++;if(population>=1000000){*errorPointer=[NSErrorerrorWithDomain:@"AppErrorDomain"code:-2userInfo:@{NSLocalizedDescriptionKey:@"Population too big"}];return@(population);}[transactionupdateData:@{@"population":@(population)}forDocument:sfReference];returnnil;}completion:^(idresult,NSError*error){if(error!=nil){NSLog(@"Transaction failed: %@",error);}else{NSLog(@"Population increased to %@",result);}}];
ViewController.m

valsfDocRef=db.collection("cities").document("SF")db.runTransaction{transaction->valsnapshot=transaction.get(sfDocRef)valnewPopulation=snapshot.getDouble("population")!!+1if(newPopulation<=1000000){transaction.update(sfDocRef,"population",newPopulation)newPopulation}else{throwFirebaseFirestoreException("Population too high",FirebaseFirestoreException.Code.ABORTED,)}}.addOnSuccessListener{result->Log.d(TAG,"Transaction success:$result")}.addOnFailureListener{e->Log.w(TAG,"Transaction failure.",e)}
DocSnippets.kt

finalDocumentReferencesfDocRef=db.collection("cities").document("SF");db.runTransaction(newTransaction.Function<Double>(){@OverridepublicDoubleapply(@NonNullTransactiontransaction)throwsFirebaseFirestoreException{DocumentSnapshotsnapshot=transaction.get(sfDocRef);doublenewPopulation=snapshot.getDouble("population")+1;if(newPopulation<=1000000){transaction.update(sfDocRef,"population",newPopulation);returnnewPopulation;}else{thrownewFirebaseFirestoreException("Population too high",FirebaseFirestoreException.Code.ABORTED);}}}).addOnSuccessListener(newOnSuccessListener<Double>(){@OverridepublicvoidonSuccess(Doubleresult){Log.d(TAG,"Transaction success: "+result);}}).addOnFailureListener(newOnFailureListener(){@OverridepublicvoidonFailure(@NonNullExceptione){Log.w(TAG,"Transaction failure.",e);}});
DocSnippets.java

finalsfDocRef=db.collection("cities").doc("SF");db.runTransaction((transaction){returntransaction.get(sfDocRef).then((sfDoc){finalnewPopulation=sfDoc.get("population")+1;transaction.update(sfDocRef,{"population":newPopulation});returnnewPopulation;});}).then((newPopulation)=>print("Population increased to$newPopulation"),onError:(e)=>print("Error updating document$e"),);
firestore.dart

// This is not yet supported.

DocumentReferencecityRef=db.Collection("cities").Document("SF");db.RunTransactionAsync(transaction=>{returntransaction.GetSnapshotAsync(cityRef).ContinueWith((task)=>{longnewPopulation=task.Result.GetValue<long>("Population")+1;if(newPopulation<=1000000){Dictionary<string,object>updates=newDictionary<string,object>{{"Population",newPopulation}};transaction.Update(cityRef,updates);returntrue;}else{returnfalse;}});}).ContinueWith((transactionResultTask)=>{if(transactionResultTask.Result){Console.WriteLine("Population updated successfully.");}else{Console.WriteLine("Sorry! Population is too big.");}});

import{writeBatch,doc}from"firebase/firestore";// Get a new write batchconstbatch=writeBatch(db);// Set the value of 'NYC'constnycRef=doc(db,"cities","NYC");batch.set(nycRef,{name:"New York City"});// Update the population of 'SF'constsfRef=doc(db,"cities","SF");batch.update(sfRef,{"population":1000000});// Delete the city 'LA'constlaRef=doc(db,"cities","LA");batch.delete(laRef);// Commit the batchawaitbatch.commit();
write_batch.js

// Get a new write batchvarbatch=db.batch();// Set the value of 'NYC'varnycRef=db.collection("cities").doc("NYC");batch.set(nycRef,{name:"New York City"});// Update the population of 'SF'varsfRef=db.collection("cities").doc("SF");batch.update(sfRef,{"population":1000000});// Delete the city 'LA'varlaRef=db.collection("cities").doc("LA");batch.delete(laRef);// Commit the batchbatch.commit().then(()=>{// ...});
test.firestore.js

// Get new write batchletbatch=db.batch()// Set the value of 'NYC'letnycRef=db.collection("cities").document("NYC")batch.setData([:],forDocument:nycRef)// Update the population of 'SF'letsfRef=db.collection("cities").document("SF")batch.updateData(["population":1000000],forDocument:sfRef)// Delete the city 'LA'letlaRef=db.collection("cities").document("LA")batch.deleteDocument(laRef)// Commit the batchdo{tryawaitbatch.commit()print("Batch write succeeded.")}catch{print("Error writing batch:\(error)")}
ViewController.swift

// Get new write batchFIRWriteBatch*batch=[self.dbbatch];// Set the value of 'NYC'FIRDocumentReference*nycRef=[[self.dbcollectionWithPath:@"cities"]documentWithPath:@"NYC"];[batchsetData:@{}forDocument:nycRef];// Update the population of 'SF'FIRDocumentReference*sfRef=[[self.dbcollectionWithPath:@"cities"]documentWithPath:@"SF"];[batchupdateData:@{@"population":@1000000}forDocument:sfRef];// Delete the city 'LA'FIRDocumentReference*laRef=[[self.dbcollectionWithPath:@"cities"]documentWithPath:@"LA"];[batchdeleteDocument:laRef];// Commit the batch[batchcommitWithCompletion:^(NSError*_Nullableerror){if(error!=nil){NSLog(@"Error writing batch %@",error);}else{NSLog(@"Batch write succeeded.");}}];
ViewController.m

valnycRef=db.collection("cities").document("NYC")valsfRef=db.collection("cities").document("SF")vallaRef=db.collection("cities").document("LA")// Get a new write batch and commit all write operationsdb.runBatch{batch->// Set the value of 'NYC'batch.set(nycRef,City())// Update the population of 'SF'batch.update(sfRef,"population",1000000L)// Delete the city 'LA'batch.delete(laRef)}.addOnCompleteListener{// ...}
DocSnippets.kt

// Get a new write batchWriteBatchbatch=db.batch();// Set the value of 'NYC'DocumentReferencenycRef=db.collection("cities").document("NYC");batch.set(nycRef,newCity());// Update the population of 'SF'DocumentReferencesfRef=db.collection("cities").document("SF");batch.update(sfRef,"population",1000000L);// Delete the city 'LA'DocumentReferencelaRef=db.collection("cities").document("LA");batch.delete(laRef);// Commit the batchbatch.commit().addOnCompleteListener(newOnCompleteListener<Void>(){@OverridepublicvoidonComplete(@NonNullTask<Void>task){// ...}});
DocSnippets.java

// Get a new write batchfinalbatch=db.batch();// Set the value of 'NYC'varnycRef=db.collection("cities").doc("NYC");batch.set(nycRef,{"name":"New York City"});// Update the population of 'SF'varsfRef=db.collection("cities").doc("SF");batch.update(sfRef,{"population":1000000});// Delete the city 'LA'varlaRef=db.collection("cities").doc("LA");batch.delete(laRef);// Commit the batchbatch.commit().then((_){// ...});
firestore.dart

// Get a new write batchWriteBatchbatch=db->batch();// Set the value of 'NYC'DocumentReferencenyc_ref=db->Collection("cities").Document("NYC");batch.Set(nyc_ref,{});// Update the population of 'SF'DocumentReferencesf_ref=db->Collection("cities").Document("SF");batch.Update(sf_ref,{{"population", FieldValue::Integer(1000000)}});// Delete the city 'LA'DocumentReferencela_ref=db->Collection("cities").Document("LA");batch.Delete(la_ref);// Commit the batchbatch.Commit().OnCompletion([](constFuture<void>&future){if(future.error()==Error::kErrorOk){std::cout <<"Write batch success!" <<std::endl;}else{std::cout <<"Write batch failure: " <<future.error_message() <<std::endl;}});
snippets.cpp

WriteBatchbatch=db.StartBatch();// Set the data for NYCDocumentReferencenycRef=db.Collection("cities").Document("NYC");Dictionary<string,object>nycData=newDictionary<string,object>{{"name","New York City"}};batch.Set(nycRef,nycData);// Update the population for SFDocumentReferencesfRef=db.Collection("cities").Document("SF");Dictionary<string,object>updates=newDictionary<string,object>{{"Population",1000000}};batch.Update(sfRef,updates);// Delete LADocumentReferencelaRef=db.Collection("cities").Document("LA");batch.Delete(laRef);// Commit the batchbatch.CommitAsync();