Projection and query for #31 to illustrate alternatives to a transaction

Author: Duncan-at-Hedgefacts

examples/bank-account/RetailBank.AzureFunctionApp/RetailBank.AzureFunctionApp.csproj

@@ -56,8 +56,4 @@
       <Private>true</Private>
     </ProjectReference>
   </ItemGroup>
-  <ItemGroup>
-    <Folder Include="Transfer\Functions\" />
-    <Folder Include="Transfer\Projections\" />
-  </ItemGroup>
 </Project>

examples/bank-account/RetailBank.AzureFunctionApp/Transfer/Events/TargetFundsDeposited.cs

@@ -1,10 +1,10 @@
 using EventSourcingOnAzureFunctions.Common.EventSourcing;
-using System;
-using System.Collections.Generic;
-using System.Text;
 
 namespace RetailBank.AzureFunctionApp.Transfer.Events
 {
+    /// <summary>
+    /// Funds being transfered have been deposited into the target account
+    /// </summary>
     [EventName("Target Funds Deposited")]
     public sealed class TargetFundsDeposited
     {

examples/bank-account/RetailBank.AzureFunctionApp/Transfer/Functions/MoneyTransferData.cs

@@ -0,0 +1,33 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace RetailBank.AzureFunctionApp.Transfer.Functions
+{
+    /// <summary>
+    /// Data used to initiate a "money transfer" request
+    /// </summary>
+    public sealed class MoneyTransferData
+    {
+
+        /// <summary>
+        /// The amount we want to transfer
+        /// </summary>
+        public decimal Amount { get; set; }
+
+        /// <summary>
+        /// The account that the transfer will come from
+        /// </summary>
+        public string SourceAccountNumber { get; set; }
+
+        /// <summary>
+        /// The account which the transfer will be paid into
+        /// </summary>
+        public string TargetAccountNumber { get; set; }
+
+        /// <summary>
+        /// Extra text attached to the transfer
+        /// </summary>
+        public string Commentary { get; set; }
+    }
+}

examples/bank-account/RetailBank.AzureFunctionApp/Transfer/Functions/TransferCommands.cs

@@ -0,0 +1,13 @@
+using EventSourcingOnAzureFunctions.Common.Binding;
+using EventSourcingOnAzureFunctions.Common.CQRS;
+using EventSourcingOnAzureFunctions.Common.EventSourcing;
+
+namespace RetailBank.AzureFunctionApp.Transfer.Functions
+{
+    public class TransferCommands
+    {
+
+
+
+    }
+}

examples/bank-account/RetailBank.AzureFunctionApp/Transfer/Functions/TransferQueries.cs

@@ -0,0 +1,79 @@
+using EventSourcingOnAzureFunctions.Common.Binding;
+using EventSourcingOnAzureFunctions.Common.EventSourcing;
+using Microsoft.Azure.WebJobs;
+using Microsoft.Azure.WebJobs.Extensions.Http;
+using System;
+using System.Collections.Generic;
+using System.Net.Http;
+using System.Text;
+using System.Threading.Tasks;
+using RetailBank.AzureFunctionApp.Transfer.Projections;
+using System.Diagnostics;
+
+namespace RetailBank.AzureFunctionApp.Transfer.Functions
+{
+
+    /// <summary>
+    /// Queries to execute against the money transfer entity
+    /// </summary>
+    public sealed class TransferQueries
+    {
+
+        // GetTransferState
+        [FunctionName("GetTransferState")]
+        public static async Task<HttpResponseMessage> GetTransferStateRun(
+          [HttpTrigger(AuthorizationLevel.Function, "GET", Route = @"GetTransferState/{transfernumber}")] HttpRequestMessage req,
+          string transfernumber,
+          [Projection("Bank", "Transfer", "{transfernumber}", nameof(TransferState))] Projection prjTransferState)
+        {
+
+            // Set the start time for how long it took to process the message
+            DateTime startTime = DateTime.UtcNow;
+
+            #region Tracing telemetry
+            Activity.Current.AddTag("Transfer Number", transfernumber);
+            #endregion
+
+            string result = $"No fund transfer found with the identifier : {transfernumber}";
+
+            if (null != prjTransferState)
+            {
+                if (await prjTransferState.Exists())
+                {
+                    // Run the "Transfer state" projection
+                    TransferState state =  await prjTransferState.Process<TransferState >();
+
+                    result = $"Transfer {transfernumber} state is {state.LastStateChange} ({state.AmountDeposited} of {state.AmountOfTransferRequested} transfered) ";
+                    return req.CreateResponse<ProjectionFunctionResponse>(System.Net.HttpStatusCode.OK,
+                            ProjectionFunctionResponse.CreateResponse(startTime,
+                            false,
+                            result,
+                            state.CurrentSequenceNumber),
+                            FunctionResponse.MEDIA_TYPE);
+
+                }
+                else
+                {
+                    // No such transfer request exists
+                    result = $"Transfer {transfernumber} is not yet created - cannot retrieve a state for it";
+                    return req.CreateResponse<ProjectionFunctionResponse>(System.Net.HttpStatusCode.NotFound,
+                        ProjectionFunctionResponse.CreateResponse(startTime,
+                        true,
+                        result,
+                        0),
+                        FunctionResponse.MEDIA_TYPE);
+                }
+            }
+
+
+            // If we got here no transfer was found
+            return req.CreateResponse<ProjectionFunctionResponse>(System.Net.HttpStatusCode.NotFound,
+                ProjectionFunctionResponse.CreateResponse(startTime,
+                true,
+                result,
+                0),
+                FunctionResponse.MEDIA_TYPE);
+        }
+
+    }
+}

examples/bank-account/RetailBank.AzureFunctionApp/Transfer/Projections/TransferState.cs

@@ -0,0 +1,124 @@
+using EventSourcingOnAzureFunctions.Common.EventSourcing;
+using System;
+using RetailBank.AzureFunctionApp.Transfer.Events;
+using EventSourcingOnAzureFunctions.Common.EventSourcing.Interfaces;
+
+namespace RetailBank.AzureFunctionApp.Transfer.Projections
+{
+    /// <summary>
+    /// A projection to return the state of a given money transfer
+    /// </summary>
+    [ProjectionName("Money Transfer State")]
+    public sealed class TransferState
+        : ProjectionBase,
+        IHandleEventType<TransferInitiated>,
+        IHandleEventType<SourceFundsWithdrawn >,
+        IHandleEventType<SourceFundsRefunded >, 
+        IHandleEventType<TargetFundsDeposited >,
+        IHandleEventType<RefundInitiated >
+    {
+
+        private string lastStateChange;
+        /// <summary>
+        /// The last state event that happened in this transfers life cycle
+        /// </summary>
+        public string LastStateChange
+        {
+            get
+            {
+                return lastStateChange;
+            }
+        }
+
+        private decimal amountOfTransferRequest;
+        /// <summary>
+        /// How much money transfer was initially requested
+        /// </summary>
+        public decimal AmountOfTransferRequested
+        {
+            get
+            {
+                return amountOfTransferRequest;
+            }
+        }
+
+        private decimal amountWithdrawn;
+        /// <summary>
+        /// The amount that has been withdrawn from the source account
+        /// </summary>
+        public decimal AmountWithdrawn
+        {
+            get
+            {
+                return amountWithdrawn;
+            }
+        }
+
+        private decimal amountToRefund;
+        public decimal AmountToRefund
+        {
+            get
+            {
+                return amountToRefund;
+            }
+        }
+
+
+        private decimal amountDeposited;
+        /// <summary>
+        /// The amound that has been deposited into the target account of the money transfer
+        /// </summary>
+        public decimal AmountDeposited
+        {
+            get
+            {
+                return amountDeposited;
+            }
+        }
+
+        public void HandleEventInstance(TransferInitiated eventInstance)
+        {
+            if (eventInstance != null)
+            {
+                lastStateChange = "Initiated";
+                amountOfTransferRequest = eventInstance.Amount;
+            }
+        }
+
+        public void HandleEventInstance(SourceFundsWithdrawn eventInstance)
+        {
+            if (eventInstance != null)
+            {
+                lastStateChange = "Source Funds Withdrawn";
+                amountWithdrawn += eventInstance.AmountWithdrawn;
+            }
+        }
+
+        public void HandleEventInstance(SourceFundsRefunded eventInstance)
+        {
+            if (eventInstance != null)
+            {
+                lastStateChange = "Source Funds Refunded";
+                amountWithdrawn -= eventInstance.AmountRefunded;
+            }
+        }
+
+        public void HandleEventInstance(TargetFundsDeposited eventInstance)
+        {
+            if (eventInstance != null)
+            {
+                lastStateChange = "Target Funds Deposited";
+                amountDeposited  += eventInstance.AmountDeposited;
+            }
+        }
+
+        public void HandleEventInstance(RefundInitiated eventInstance)
+        {
+            if (eventInstance != null)
+            {
+                lastStateChange = "Refund Initiated";
+                amountToRefund += eventInstance.AmountToRefund;
+            }
+        }
+    }
+}