Struct TransactUpdateRequest 

pub struct TransactUpdateRequest<TD: TableDefinition, T = (), C: ConditionState = NoCondition> { /* private fields */ }

Builder for an Update operation inside a DynamoDB transaction.

Constructed via DynamoDBItemTransactOp::transact_update or DynamoDBItemTransactOp::transact_update_by_id. Optionally add a condition that must hold for the update to succeed, via .condition(), .exists(), or .not_exists(). DynamoDB accepts a single condition expression per operation, so this can only be called once.

Call .build() to produce a TransactWriteItem that can be passed to the SDK’s transact_write_items() builder.

Examples

Atomically promote a user to instructor and create their first enrollment:

use dynamodb_facade::{Condition, DynamoDBItemTransactOp, KeyId, Update};

let enrollment = sample_enrollment();

client
    .transact_write_items()
    .transact_items(
        User::transact_update_by_id(
            KeyId::pk("user-1"),
            Update::set("role", "instructor"),
        )
        .condition(Condition::not_exists("role"))
        .build(),
    )
    .transact_items(enrollment.transact_put().not_exists().build())
    .send()
    .await?;

Implementations

impl<TD: TableDefinition, T, C: ConditionState> TransactUpdateRequest<TD, T, C>

pub fn new(key: Key<TD>, update: Update<'_>) -> Self

Creates a new TransactUpdateRequest from a raw Key and an Update expression.

Prefer DynamoDBItemTransactOp::transact_update or DynamoDBItemTransactOp::transact_update_by_id for typed construction.

pub fn into_inner(self) -> UpdateBuilder

Consumes the builder and returns the underlying SDK UpdateBuilder.

Use this escape hatch when you need to set options not exposed by this facade.

pub fn build(self) -> TransactWriteItem

Finalizes the builder and returns a TransactWriteItem.

The returned value can be passed directly to the SDK’s transact_write_items().transact_items(...) call.

Examples

use dynamodb_facade::{Condition, DynamoDBItemTransactOp, KeyId, Update};

let enrollment = sample_enrollment();

// Atomically promote a user and create an enrollment
client
    .transact_write_items()
    .transact_items(
        User::transact_update_by_id(
            KeyId::pk("user-1"),
            Update::set("role", "instructor"),
        )
        .condition(Condition::not_exists("role"))
        .build(),
    )
    .transact_items(enrollment.transact_put().not_exists().build())
    .send()
    .await?;

impl<TD: TableDefinition, T> TransactUpdateRequest<TD, T, NoCondition>

pub fn condition( self, condition: Condition<'_>, ) -> TransactUpdateRequest<TD, T, AlreadyHasCondition>

Adds a condition expression that must be satisfied for the update to succeed.

DynamoDB accepts a single condition expression per operation, so this method can only be called once. If the condition fails, the entire transaction is cancelled.

Examples

use dynamodb_facade::{DynamoDBItemTransactOp, KeyId, Update, Condition};

let transact_item = User::transact_update_by_id(
    KeyId::pk("user-1"),
    Update::set("role", "instructor"),
)
.condition(Condition::not_exists("role"))
.build();

impl<TD: TableDefinition, T: DynamoDBItem<TD>> TransactUpdateRequest<TD, T, NoCondition>

pub fn exists(self) -> TransactUpdateRequest<TD, T, AlreadyHasCondition>

Adds an attribute_exists(<PK>) condition.

Examples

use dynamodb_facade::{DynamoDBItemTransactOp, KeyId, Update};

let transact_item = User::transact_update_by_id(
    KeyId::pk("user-1"),
    Update::increment("enrollment_count", 1),
)
.exists()
.build();

pub fn not_exists(self) -> TransactUpdateRequest<TD, T, AlreadyHasCondition>

Adds an attribute_not_exists(<PK>) condition.

Useful for upsert-style updates that must only apply when the item does not yet exist.

Examples

use dynamodb_facade::{DynamoDBItemTransactOp, KeyId, Update};

// Initialize enrollment progress only if the enrollment doesn't exist yet
let transact_item = Enrollment::transact_update_by_id(
    KeyId::pk("user-1").sk("course-42"),
    Update::set("progress", 0.0),
)
.not_exists()
.build();