Oli Sturm
90 lines
3.3 KiB
C#
90 lines
3.3 KiB
C#
using System.Collections.Immutable;
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using CsharpEs.Domain;
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using CsharpEs.Infrastructure;
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using CsharpEs.Library;
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public abstract record DemoError
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{
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public sealed record Account(AccountError Error) : DemoError;
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public sealed record ReadModel(ReadModelError Error) : DemoError;
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}
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public class Program
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{
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private static Guid accountId;
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private static ImmutableList<AccountCommand> demoCommands = ImmutableList<AccountCommand>.Empty;
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static Program()
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{
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accountId = Guid.NewGuid();
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demoCommands = demoCommands.AddRange([
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// bring this in to see an error right from the start
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// new AccountCommand.OpenAccount(accountId, new Money(-200m)),
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new AccountCommand.OpenAccount(accountId, new Money(200m)),
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new AccountCommand.WithdrawMoney(accountId, new Money(100m)),
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new AccountCommand.WithdrawMoney(accountId, new Money(200m)),
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// or maybe an exception in between?
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// new AccountCommand.UnhandledTestCommand(),
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new AccountCommand.DepositMoney(accountId, new Money(500m)),
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]);
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}
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static ImmutableList<AccountEvent> eventStore = ImmutableList<AccountEvent>.Empty;
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static Result<AccountState?, DemoError> ApplyEvent(
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AccountBalanceReadModel balanceProjection,
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AccountState? state,
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AccountEvent @event
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)
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{
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eventStore = eventStore.Add(@event);
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Logging.Output(
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"ae",
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$"Applying event {Logging.Format(@event)} to state {Logging.Format(state)}"
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);
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return AccountDecider
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.Evolve(state, @event)
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.MapError(e => (DemoError)new DemoError.Account(e))
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.Bind(newState =>
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balanceProjection
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.Project(@event)
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.MapError(e => (DemoError)new DemoError.ReadModel(e))
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.Log("ae ad", "Account details")
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.Map(_ => newState)
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)
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.Log("ae", $"Applied and projected {Logging.Format(@event)}");
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}
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public static void Main(string[] args)
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{
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Logging.Output("csharp-es", "Starting money handling demo...");
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AccountBalanceReadModelModule
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.Create()
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.MapError(e => (DemoError)new DemoError.ReadModel(e))
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.Bind(readModel =>
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demoCommands
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.Aggregate(
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Result<AccountState?, DemoError>.Ok(null),
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(stateResult, command) =>
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stateResult
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.Bind(state =>
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AccountDecider
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.Decide(state, command)
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.MapError(e => (DemoError)new DemoError.Account(e))
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.Bind(@event => ApplyEvent(readModel, state, @event))
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)
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.Log("loop", "Intermediate state")
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)
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.Bind(s =>
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readModel
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.Query()
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.Log("query", "Read model data")
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.MapError(e => (DemoError)new DemoError.ReadModel(e))
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)
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)
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.Log("csharp-es done", "Demo completed.");
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}
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}
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