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Transactions

DynamoDB provides two transactional operations:

  • TransactGetItems - Atomically read multiple items from one or more tables.
  • TransactWriteItems - Atomically modify multiple items in one or more tables.

Both operations throw TransactionCanceledException when transaction is rejected. The CancellationReasons property can be used to find out the reason behind the rejection.

TransactGetItems​

Atomically retrieves up to 25 items from one or more tables within the same AWS account and Region.

Each entity primary key is configured using Transact.GetItem factory method.

var items = await context.TransactGet()
    .WithItems(
        Transact.GetItem<EntityClass>().WithPrimaryKey("partitionKey", "sortKey_1"),
        Transact.GetItem<EntityClass>().WithPrimaryKey("partitionKey", "sortKey_2")
    )
    .ToListAsync<MixedEntity>()

Entities of different type can be retrieved by using AsDocuments() method the same way as for other read operations.

TransactWriteItems​

Atomically applies one of four operations per item within the same AWS account and Region (up to 25 operations):

  • Transact.PutItem - applies a PutItem operation.
  • Transact.UpdateItem - applies an UpdateItem operation.
  • Transact.DeleteItem - applies a DeleteItem operation.
  • Transact.ConditionCheck - applies a condition to an item which is not modified by the transaction.
await context.TransactWrite()
    .WithClientRequestToken(idempotencyKey)
    .WithItems(
        Transact.PutItem(new UserEmailEntity("test@test.com")),
        Transact.ConditionCheck<UserEntity>()
            .WithPrimaryKey("partitionKey", "sortKey")
            .WithCondition(Condition<UserEntity>.On(x => x.Verified).EqualTo(false))
    )
    .ExecuteAsync();