#include <userver/storages/mongo/transaction.hpp>

Detailed Description

MongoDB transaction handle that provides ACID guarantees.

Transactions group multiple operations within logical units of work and provide ACID guarantees. All operations in a transaction either succeed completely or fail completely.

Usage example:

    auto txn = GetDefaultPool().BeginTransaction();
    auto collection = txn.GetCollection(kCollectionName);
 
    // Insert multiple documents
    std::vector<formats::bson::Document> docs;
    for (int i = 0; i < 5; ++i) {
        docs.push_back(bson::MakeDoc("name", fmt::format("user_{}", i), "age", 20 + i));
    }
 
    auto insert_result = collection.InsertMany(docs);
    EXPECT_EQ(insert_result.InsertedCount(), 5);
 
    // Update one document
    auto filter = bson::MakeDoc("name", "user_2");
    auto update = bson::MakeDoc("$set", bson::MakeDoc("age", 100));
 
    auto update_result = collection.UpdateOne(filter, update);
    EXPECT_EQ(update_result.ModifiedCount(), 1);
 
    // Delete one document
    auto delete_filter = bson::MakeDoc("name", "user_4");
    auto delete_result = collection.DeleteOne(delete_filter);
    EXPECT_EQ(delete_result.DeletedCount(), 1);
 
    // Commit all operations
    txn.Commit();

Note: Transactions require MongoDB replica sets or sharded clusters.; Operations within a transaction are automatically retried according to MongoDB transaction retry semantics.

Definition at line 33 of file transaction.hpp.

Public Types
enum class	State { kNone , kInProgress , kCommitted , kAborted }
	Get the transaction state. More...

Public Member Functions
	Transaction ()
	Creates invalid transaction.

	Transaction (Transaction &&) noexcept
	Move constructor.

Transaction &	operator= (Transaction &&) noexcept
	Move assignment operator.

	~Transaction ()
	Destructor. Aborts transaction if not committed.

Collection	GetCollection (std::string name)
	Get a collection handle within the transaction context.

void	Commit ()
	Commit the transaction.

void	Abort () noexcept
	Abort the transaction.

bool	IsActive () const noexcept
	Check if transaction is active.

State	GetState () const noexcept
	Get current transaction state.

Member Enumeration Documentation

◆ State

enum class storages::mongo::Transaction::State

strong

Get the transaction state.

Enumerator
kNone	Transaction not started.
kInProgress	Transaction is active.
kCommitted	Transaction has been committed.
kAborted	Transaction has been aborted.

Definition at line 77 of file transaction.hpp.

Member Function Documentation

◆ Abort()

void storages::mongo::Transaction::Abort ( )

noexcept

Abort the transaction.

Discards all changes made within the transaction. This method is idempotent and safe to call multiple times.

◆ Commit()

void storages::mongo::Transaction::Commit ( )

Commit the transaction.

Makes all changes within the transaction permanent and visible to other operations. If the transaction fails to commit, an exception will be thrown.

Exceptions

MongoException on commit failure

◆ GetCollection()

Collection storages::mongo::Transaction::GetCollection ( std::string name )

Get a collection handle within the transaction context.

Parameters

name	collection name

Returns: Collection handle that operates within this transaction

◆ IsActive()

bool storages::mongo::Transaction::IsActive ( ) const