public Task when_stopping_a_started_group()
{
var groupId = new GroupIdentifier(Guid.NewGuid());
var administratorId = new GroupAdministratorIdentifier(Guid.NewGuid());
return(new Scenario()
.Given(groupId,
new GroupStarted(
groupId,
"Elvis Afficionados",
administratorId,
0)
)
.When(new StopGroup(
groupId.ToGuid(),
administratorId))
.Then(groupId,
new GroupStopped(
groupId,
"Elvis Afficionados",
administratorId,
0)
)
.AssertAsync(_runner));
}
void ISnapshotSource.RestoreFromSnapshot(object snapshot)
{
if (snapshot is GroupSnapshot data)
{
_groupId = new GroupIdentifier(data.GroupId);
_name = new GroupName(data.Name);
_active = data.Active;
}
}
public async Task <Group> TryLoadById(GroupIdentifier identifier, CancellationToken ct = default(CancellationToken))
{
var stream = new StreamName($"groups-{identifier.ToGuid():N}");
var result = await _reader.ReadStreamAsync(stream, ct);
if (result.State == ReadResultState.Deleted)
{
throw new GroupDeletedException(identifier);
}
return(result.State == ReadResultState.Found ? (Group)result.Value : null);
}
public static Group Start(GroupIdentifier groupId, GroupName name, GroupAdministratorIdentifier startedBy)
{
var group = new Group();
group.Raise(new GroupStarted(
groupId.ToGuid(),
name.ToString(),
startedBy.ToGuid(),
0 // DateTimeOffset.UtcNow.Ticks
));
return(group);
}
public static void Usage()
{
var groupId = new GroupIdentifier(Guid.NewGuid());
var groupName = new GroupName("Elvis Fanclub");
var john = new GroupAdministratorIdentifier(Guid.NewGuid());
var jane = new GroupAdministratorIdentifier(Guid.NewGuid());
//Start a group (imagine a command)
var group = Group.Start(groupId, groupName, john);
PrintRecords(group);
//Stop a group (imagine a command)
group.Stop(jane);
PrintRecords(group);
//Take a snapshot of the group
var source = (ISnapshotSource)group;
var snapshot = source.TakeSnapshot();
//Restore another instance from the snapshot
var groupFromStore = Group.Factory();
var destination = (ISnapshotSource)groupFromStore;
destination.RestoreFromSnapshot(snapshot);
//Here's an example of a composition root
var settings = new JsonSerializerSettings();
var invoker = new CommandHandlerInvoker(
new CommandHandlerModule[]
{
new GroupModule(
new GroupRepository(
null, /* todo - connection to embedded eventstore */
new EventSourceReaderConfiguration(
StreamNameConversions.PassThru,
() =>
new StreamEventsSliceTranslator(
typeName => Type.GetType(typeName, true),
settings),
new SliceSize(100)),
new EventSourceWriterConfiguration(
StreamNameConversions.PassThru,
new EventSourceChangesetTranslator(type => type.FullName, settings))))
});
// Somewhere in the infrastructure, probably as part of an IHandleCommand<> (see below)
var command =
/* typically comes from the wire, here in deserialized shape. */
new StartGroup(Guid.NewGuid(), "Fans of Elvis", Guid.NewGuid());
invoker.Invoke(new CommandEnvelope().SetCommand(command)).Wait(); //Don't block obviously, go full async.
}
private Group()
{
Register <GroupStarted>(_ =>
{
_groupId = new GroupIdentifier(_.GroupId);
_name = new GroupName(_.Name);
_active = true;
});
Register <GroupStopped>(_ =>
{
_active = false;
});
}
public async Task <Group> LoadById(GroupIdentifier identifier, CancellationToken ct = default(CancellationToken))
{
var stream = new StreamName($"groups-{identifier.ToGuid():N}");
var result = await _reader.ReadStreamAsync(stream, ct);
switch (result.State)
{
case ReadResultState.NotFound:
throw new GroupNotFoundException(identifier);
case ReadResultState.Deleted:
throw new GroupDeletedException(identifier);
}
return((Group)result.Value);
}
public GroupDeletedException(GroupIdentifier identifier)
: base($"The group with identifier {identifier.ToGuid():N} was deleted.")
{
}
public GroupNotFoundException(GroupIdentifier identifier)
: base($"The group with identifier {identifier.ToGuid():N} could not be found.")
{
}
