Multi transaction API changes

README.md

@@ -269,25 +269,26 @@ let doesntExistCondition = compile <@ fun t -> NOT_EXISTS t.Value @>
 let existsCondition = compile <@ fun t -> EXISTS t.Value @>
 let key = TableKey.Combined(hashKey, rangeKey)
 
-let transaction = Transaction()
+let transaction = table.CreateTransaction()
 
 transaction.Check(table, key, doesntExistCondition)
 transaction.Put(table, item2, None)
 transaction.Put(table, item3, Some existsCondition)
-transaction.Delete (table ,table.Template.ExtractKey item5, None)
+transaction.Delete(table, table.Template.ExtractKey item5, None)
+
 do! transaction.TransactWriteItems()
 ```
 
-Failed preconditions (or `TransactWrite.Check`s) are signalled as per the underlying API: via a `TransactionCanceledException`.
-Use `TransactWriteItemsRequest.TransactionCanceledConditionalCheckFailed` to trap such conditions:
+Failed preconditions (or `Check`s) are signalled as per the underlying API: via a `TransactionCanceledException`.
+Use `Transaction.TransactionCanceledConditionalCheckFailed` to trap such conditions:
 
 ```fsharp
 try do! transaction.TransactWriteItems()
         return Some result
-with TransactWriteItemsRequest.TransactionCanceledConditionalCheckFailed -> return None 
+with Transaction.TransactionCanceledConditionalCheckFailed -> return None 
 ```
 
-See [`TransactWriteItems tests`](./tests/FSharp.AWS.DynamoDB.Tests/SimpleTableOperationTests.fs#130) for more details and examples.
+See [`TransactWriteItems tests`](./tests/FSharp.AWS.DynamoDB.Tests/SimpleTableOperationTests.fs#156) for more details and examples.
 
 It generally costs [double or more the Write Capacity Units charges compared to using precondition expressions](https://zaccharles.medium.com/calculating-a-dynamodb-items-size-and-consumed-capacity-d1728942eb7c)
 on individual operations.

RELEASE_NOTES.md

@@ -1,3 +1,6 @@
+### 0.12.2-beta
+* (breaking) Revised multi-table transaction API (thanks @bartelink)
+
 ### 0.12.1-beta
 * Added support for `defaultArg` in update expressions on the same attribute, allowing SET if_not_exists semantics (eg { record with OptionalValue = Some (defaultArg record.OptionalValue "Default") })
 * Allow empty strings in non-key attributes (thanks @purkhusid)

src/FSharp.AWS.DynamoDB/TableContext.fs

@@ -1318,22 +1318,17 @@ type TableContext<'TRecord>
         else
             t.VerifyTableAsync()
 
-    member t.Transaction() =
-        match metricsCollector with
-        | Some metricsCollector -> Transaction(metricsCollector = metricsCollector)
-        | None -> Transaction()
+    /// <summary>Creates a new `Transaction`, using the DynamoDB client and metricsCollector configured for this `TableContext`</summary>
+    member _.CreateTransaction() =
+        Transaction(client, ?metricsCollector = metricsCollector)
 
 /// <summary>
 ///    Represents a transactional set of operations to be applied atomically to a arbitrary number of DynamoDB tables.
 /// </summary>
+/// <param name="client">DynamoDB client instance</param>
 /// <param name="metricsCollector">Function to receive request metrics.</param>
-and Transaction(?metricsCollector: (RequestMetrics -> unit)) =
+and Transaction(client: IAmazonDynamoDB, ?metricsCollector: (RequestMetrics -> unit)) =
     let transactionItems = ResizeArray<TransactWriteItem>()
-    let mutable (dynamoDbClient: IAmazonDynamoDB) = null
-
-    let setClient client =
-        if dynamoDbClient = null then
-            dynamoDbClient <- client
 
     let reportMetrics collector (tableName: string) (operation: Operation) (consumedCapacity: ConsumedCapacity list) (itemCount: int) =
         collector
@@ -1353,35 +1348,30 @@ and Transaction(?metricsCollector: (RequestMetrics -> unit)) =
     /// <param name="tableContext">Table context to operate on.</param>
     /// <param name="item">Item to be put.</param>
     /// <param name="precondition">Optional precondition expression.</param>
-    member this.Put<'TRecord>
+    member _.Put<'TRecord>
         (
             tableContext: TableContext<'TRecord>,
             item: 'TRecord,
             ?precondition: ConditionExpression<'TRecord>
-        ) : Transaction =
-        setClient tableContext.Client
+        ) =
         let req = Put(TableName = tableContext.TableName, Item = tableContext.Template.ToAttributeValues item)
         precondition
         |> Option.iter (fun cond ->
             let writer = AttributeWriter(req.ExpressionAttributeNames, req.ExpressionAttributeValues)
             req.ConditionExpression <- cond.Conditional.Write writer)
         transactionItems.Add(TransactWriteItem(Put = req))
-        this
 
     /// <summary>
     ///   Adds a ConditionCheck operation to the transaction.
     /// </summary>
     /// <param name="tableContext">Table context to operate on.</param>
     /// <param name="key">Key of item to check.</param>
     /// <param name="condition">Condition to check.</param>
-    member this.Check(tableContext: TableContext<'TRecord>, key: TableKey, condition: ConditionExpression<'TRecord>) : Transaction =
-        setClient tableContext.Client
-
+    member _.Check(tableContext: TableContext<'TRecord>, key: TableKey, condition: ConditionExpression<'TRecord>) =
         let req = ConditionCheck(TableName = tableContext.TableName, Key = tableContext.Template.ToAttributeValues key)
         let writer = AttributeWriter(req.ExpressionAttributeNames, req.ExpressionAttributeValues)
         req.ConditionExpression <- condition.Conditional.Write writer
         transactionItems.Add(TransactWriteItem(ConditionCheck = req))
-        this
 
     /// <summary>
     ///   Adds an Update operation to the transaction.
@@ -1390,44 +1380,38 @@ and Transaction(?metricsCollector: (RequestMetrics -> unit)) =
     /// <param name="key">Key of item to update.</param>
     /// <param name="updater">Update expression.</param>
     /// <param name="precondition">Optional precondition expression.</param>
-    member this.Update
+    member _.Update
         (
             tableContext: TableContext<'TRecord>,
             key: TableKey,
             updater: UpdateExpression<'TRecord>,
             ?precondition: ConditionExpression<'TRecord>
 
-        ) : Transaction =
-        setClient tableContext.Client
-
+        ) =
         let req = Update(TableName = tableContext.TableName, Key = tableContext.Template.ToAttributeValues key)
         let writer = AttributeWriter(req.ExpressionAttributeNames, req.ExpressionAttributeValues)
         req.UpdateExpression <- updater.UpdateOps.Write(writer)
         precondition |> Option.iter (fun cond -> req.ConditionExpression <- cond.Conditional.Write writer)
         transactionItems.Add(TransactWriteItem(Update = req))
-        this
 
     /// <summary>
     ///  Adds a Delete operation to the transaction.
     /// </summary>
     /// <param name="tableContext">Table context to operate on.</param>
     /// <param name="key">Key of item to delete.</param>
     /// <param name="precondition">Optional precondition expression.</param>
-    member this.Delete
+    member _.Delete
         (
             tableContext: TableContext<'TRecord>,
             key: TableKey,
-            precondition: option<ConditionExpression<'TRecord>>
-        ) : Transaction =
-        setClient tableContext.Client
-
+            ?precondition: ConditionExpression<'TRecord>
+        ) =
         let req = Delete(TableName = tableContext.TableName, Key = tableContext.Template.ToAttributeValues key)
         precondition
         |> Option.iter (fun cond ->
             let writer = AttributeWriter(req.ExpressionAttributeNames, req.ExpressionAttributeValues)
             req.ConditionExpression <- cond.Conditional.Write writer)
         transactionItems.Add(TransactWriteItem(Delete = req))
-        this
 
     /// <summary>
     ///     Atomically applies a set of 1-100 operations to the table.<br/>
@@ -1436,13 +1420,13 @@ and Transaction(?metricsCollector: (RequestMetrics -> unit)) =
     /// </summary>
     /// <param name="clientRequestToken">The <c>ClientRequestToken</c> to supply as an idempotency key (10 minute window).</param>
     member _.TransactWriteItems(?clientRequestToken) : Async<unit> = async {
-        if (Seq.length transactionItems) = 0 || (Seq.length transactionItems) > 100 then
+        if transactionItems.Count = 0 || transactionItems.Count > 100 then
             raise
             <| System.ArgumentOutOfRangeException(nameof transactionItems, "must be between 1 and 100 items.")
-        let req = TransactWriteItemsRequest(ReturnConsumedCapacity = returnConsumedCapacity, TransactItems = (ResizeArray transactionItems))
+        let req = TransactWriteItemsRequest(ReturnConsumedCapacity = returnConsumedCapacity, TransactItems = transactionItems)
         clientRequestToken |> Option.iter (fun x -> req.ClientRequestToken <- x)
         let! ct = Async.CancellationToken
-        let! response = dynamoDbClient.TransactWriteItemsAsync(req, ct) |> Async.AwaitTaskCorrect
+        let! response = client.TransactWriteItemsAsync(req, ct) |> Async.AwaitTaskCorrect
         maybeReport
         |> Option.iter (fun r ->
             response.ConsumedCapacity
@@ -2150,8 +2134,8 @@ module Scripting =
             let spec = Throughput.Provisioned provisionedThroughput
             t.UpdateTableIfRequiredAsync(spec) |> Async.Ignore |> Async.RunSynchronously
 
-/// Helpers for working with <c>TransactWriteItemsRequest</c>
-module TransactWriteItemsRequest =
+/// Helpers for working with <c>Transaction</c>
+module Transaction =
     /// <summary>Exception filter to identify whether a <c>TransactWriteItems</c> call has failed due to
     /// one or more of the supplied <c>precondition</c> checks failing.</summary>
     let (|TransactionCanceledConditionalCheckFailed|_|): exn -> unit option =

tests/FSharp.AWS.DynamoDB.Tests/MetricsCollectorTests.fs

@@ -106,10 +106,9 @@ type Tests(fixture: TableFixture) =
         collector.Clear()
 
         let item = mkItem (guid ()) (guid ()) 0
-        do!
-            Transaction(collector.Collect)
-                .Put(sut, item, compile <@ fun t -> NOT_EXISTS t.RangeKey @>)
-                .TransactWriteItems()
+        let transaction = Transaction(sut.Client, collector.Collect)
+        transaction.Put(sut, item, compile <@ fun t -> NOT_EXISTS t.RangeKey @>)
+        do! transaction.TransactWriteItems()
 
         test
             <@
@@ -131,14 +130,14 @@ type Tests(fixture: TableFixture) =
         let sut = rawTable.WithMetricsCollector(collector.Collect)
 
         let item = mkItem (guid ()) (guid ()) 0
+        let transaction = rawTable.CreateTransaction()
+        transaction.Put(sut, item, compile <@ fun t -> EXISTS t.RangeKey @>)
         let mutable failed = false
         try
             do!
                 // The check will fail, which triggers a throw from the underlying AWS SDK; there's no way to extract the consumption info in that case
-                Transaction()
-                    .Put(sut, item, compile <@ fun t -> EXISTS t.RangeKey @>)
-                    .TransactWriteItems()
-        with TransactWriteItemsRequest.TransactionCanceledConditionalCheckFailed ->
+                transaction.TransactWriteItems()
+        with Transaction.TransactionCanceledConditionalCheckFailed ->
             failed <- true
         true =! failed
         [] =! collector.Metrics

tests/FSharp.AWS.DynamoDB.Tests/SimpleTableOperationTests.fs

@@ -182,10 +182,9 @@ type ``TransactWriteItems tests``(table1: TableFixture, table2: TableFixture) =
     [<Fact>]
     let ``Minimal happy path`` () = async {
         let item = mkItem ()
-        do!
-            Transaction()
-                .Put(table1, item, doesntExistConditionTable1)
-                .TransactWriteItems()
+        let transaction = table1.CreateTransaction()
+        transaction.Put(table1, item, doesntExistConditionTable1)
+        do! transaction.TransactWriteItems()
 
         let! itemFound = table1.ContainsKeyAsync(table1.Template.ExtractKey item)
         true =! itemFound
@@ -196,11 +195,10 @@ type ``TransactWriteItems tests``(table1: TableFixture, table2: TableFixture) =
         let item = mkItem ()
         let compatibleItem = mkCompatibleItem ()
 
-        do!
-            Transaction()
-                .Put(table1, item, doesntExistConditionTable1)
-                .Put(table2, compatibleItem, doesntExistConditionTable2)
-                .TransactWriteItems()
+        let transaction = table1.CreateTransaction()
+        transaction.Put(table1, item, doesntExistConditionTable1)
+        transaction.Put(table2, compatibleItem, doesntExistConditionTable2)
+        do! transaction.TransactWriteItems()
 
         let! itemFound = table1.ContainsKeyAsync(table1.Template.ExtractKey item)
         true =! itemFound
@@ -213,13 +211,12 @@ type ``TransactWriteItems tests``(table1: TableFixture, table2: TableFixture) =
     let ``Minimal Canceled path`` () = async {
         let item = mkItem ()
 
+        let transaction = table1.CreateTransaction()
+        transaction.Put(table1, item, existsConditionTable1)
         let mutable failed = false
         try
-            do!
-                Transaction()
-                    .Put(table1, item, existsConditionTable1)
-                    .TransactWriteItems()
-        with TransactWriteItemsRequest.TransactionCanceledConditionalCheckFailed ->
+            do! transaction.TransactWriteItems()
+        with Transaction.TransactionCanceledConditionalCheckFailed ->
             failed <- true
 
         true =! failed
@@ -233,18 +230,17 @@ type ``TransactWriteItems tests``(table1: TableFixture, table2: TableFixture) =
         let item, item2 = mkItem (), mkItem ()
         let! key = table1.PutItemAsync item
 
-        let transaction =
-            if shouldFail then
-                Transaction().Check(table1, key, doesntExistConditionTable1)
-            else
-                Transaction()
-                    .Check(table1, key, existsConditionTable1)
-                    .Put(table1, item2)
+        let transaction = table1.CreateTransaction()
+        if shouldFail then
+            transaction.Check(table1, key, doesntExistConditionTable1)
+        else
+            transaction.Check(table1, key, existsConditionTable1)
+            transaction.Put(table1, item2)
 
         let mutable failed = false
         try
             do! transaction.TransactWriteItems()
-        with TransactWriteItemsRequest.TransactionCanceledConditionalCheckFailed ->
+        with Transaction.TransactionCanceledConditionalCheckFailed ->
             failed <- true
 
         failed =! shouldFail
@@ -257,14 +253,14 @@ type ``TransactWriteItems tests``(table1: TableFixture, table2: TableFixture) =
     let ``All paths`` shouldFail = async {
         let item, item2, item3, item4, item5, item6, item7 = mkItem (), mkItem (), mkItem (), mkItem (), mkItem (), mkItem (), mkItem ()
         let! key = table1.PutItemAsync item
-        let transaction = Transaction()
+        let transaction = table1.CreateTransaction()
 
         let requests =
             [ transaction.Update(table1, key, compileUpdateTable1 <@ fun t -> { t with Value = 42 } @>, existsConditionTable1)
               transaction.Put(table1, item2)
               transaction.Put(table1, item3, doesntExistConditionTable1)
-              transaction.Delete(table1, table1.Template.ExtractKey item4, Some doesntExistConditionTable1)
-              transaction.Delete(table1, table1.Template.ExtractKey item5, None)
+              transaction.Delete(table1, table1.Template.ExtractKey item4, doesntExistConditionTable1)
+              transaction.Delete(table1, table1.Template.ExtractKey item5)
               transaction.Check(
                   table1,
                   table1.Template.ExtractKey item6,
@@ -281,7 +277,7 @@ type ``TransactWriteItems tests``(table1: TableFixture, table2: TableFixture) =
         let mutable failed = false
         try
             do! transaction.TransactWriteItems()
-        with TransactWriteItemsRequest.TransactionCanceledConditionalCheckFailed ->
+        with Transaction.TransactionCanceledConditionalCheckFailed ->
             failed <- true
         failed =! shouldFail
 
@@ -310,13 +306,12 @@ type ``TransactWriteItems tests``(table1: TableFixture, table2: TableFixture) =
 
     [<Fact>]
     let ``Empty request list is rejected with AORE`` () =
-        shouldBeRejectedWithArgumentOutOfRangeException (Transaction())
+        shouldBeRejectedWithArgumentOutOfRangeException (Transaction(table1.Client))
         |> Async.RunSynchronously
-        |> ignore
 
     [<Fact>]
     let ``Over 100 writes are rejected with AORE`` () =
-        let Transaction = Transaction()
+        let Transaction = Transaction(table1.Client)
         for _x in 1..101 do
             Transaction.Put(table1, mkItem ()) |> ignore