ARCCHR0017: [EventStreamId] template is invalid

Rule

On a command, [EventStreamId("{ReportingScopeId}:{Period}")] is a template. Arc resolves each {Name} from the command’s public instance properties. {{ and }} write literal braces, and a value without placeholders is a constant stream id that this rule does not inspect.

The rule reports, on the attribute value, each of:

• a placeholder that is not a public instance property of the command (unknown, private, internal, static or an indexer);
• a placeholder whose type does not convert to a string part: the supported types are string, primitives, decimal, Guid, enums, DateOnly, DateTime, DateTimeOffset, TimeOnly, TimeSpan, ConceptAs<T> over one of these, and EventSourceId derived types, each optionally nullable;
• malformed braces: an unclosed {, a stray }, or an empty {}.

Severity

Error

Example

[Command]
[EventStreamId("{Scope}:{Period}")] // ARCCHR0017: 'Period' is not a public instance property
public record CloseBooks(string Scope)
{
    ...
}

Add a public Period property of a supported type, or write {{Period}} if you meant literal braces.

Not resolved outside commands

Only Arc commands resolve templates. A reactor reads the same attribute as a literal constant, so a template there is reported by ARCCHR0018.

See also

• Concurrency
• Stream decisions