clockworklabs/SpacetimeDB · error · InvalidOperationException

Enum does not have a [SpacetimeDB.Type] attribute

Error message

Enum {type} does not have a [SpacetimeDB.Type] attribute

What it means

When a named type is an enum, GetTypeInfoForNamedType requires the [SpacetimeDB.Type] attribute (checked by looking for SpacetimeDB.TypeAttribute) before emitting SpacetimeDB.BSATN.Enum<...>; without it, it throws InvalidOperationException. Enum membership in the module schema is deliberately explicit — the attribute is what makes the generator emit BSATN and client bindings for the enum.

Solutions

1. Add [SpacetimeDB.Type] to the enum declaration
2. Make sure the attribute resolves — add `using SpacetimeDB;` or fully qualify [SpacetimeDB.Type]
3. For third-party enums you cannot edit, store the underlying integer and convert at the edges
4. Rebuild after adding the attribute

Example fix

// before
public enum Status { Offline, Online }

[SpacetimeDB.Table(Public = true)]
public partial struct Player {
    public Status Status; // throws: no [SpacetimeDB.Type]
}

// after
using SpacetimeDB;

[SpacetimeDB.Type]
public enum Status { Offline, Online }

[SpacetimeDB.Table(Public = true)]
public partial struct Player {
    public Status Status;
}

// Convention check for schema projects (compile-time enforced by the generator):
//   every enum used in tables/reducers carries [SpacetimeDB.Type]
//   and `using SpacetimeDB;` is present in that file.

// compile-time error: nothing to catch. Add the attribute and rebuild.

When it happens

Trigger: Declaring `enum Status { ... }` without [SpacetimeDB.Type] and then using it as a table column, reducer parameter, or member of another [SpacetimeDB.Type] type. Also triggers when the attribute is spelled differently or comes from another namespace.

Common situations: Assuming enums are picked up automatically the way [SpacetimeDB.Table] tables are; writing [Type] without `using SpacetimeDB;`; using a third-party enum you cannot annotate in a schema type.

Related errors

• Unsupported special type
• Unsupported system type
• Unsupported type
• Unsupported type
• Could not resolve type

AI-assisted analysis of clockworklabs/SpacetimeDB@6dee26c6ef (2026-08-20). Data as JSON: /api/errors/8bc02cc46ef77257. Report an issue: GitHub.

Appendix: source

Thrown at crates/bindings-csharp/BSATN.Codegen/Utils.cs:162

                ? "SpacetimeDB.BSATN.ByteArray"
                : $"SpacetimeDB.BSATN.Array<{elementType}, {GetTypeInfo(elementType)}>",
            _ => throw new InvalidOperationException($"Unsupported type {type}"),
        };

        static string GetTypeInfoForNamedType(INamedTypeSymbol type)
        {
            if (type.TypeKind == Microsoft.CodeAnalysis.TypeKind.Error)
            {
                throw new UnresolvedTypeException(type);
            }
            if (type.TypeKind == Microsoft.CodeAnalysis.TypeKind.Enum)
            {
                if (
                    !type.GetAttributes()
                        .Any(a => a.AttributeClass?.ToString() == "SpacetimeDB.TypeAttribute")
                )
                {
                    throw new InvalidOperationException(
                        $"Enum {type} does not have a [SpacetimeDB.Type] attribute"
                    );
                }
                return $"SpacetimeDB.BSATN.Enum<{SymbolToName(type)}>";
            }
            var result = type.OriginalDefinition.ToString() switch
            {
                // {U/I}{128/256} are not treated by C# as regular primitives, so we need to match them by type name.
                "System.Int128" => "SpacetimeDB.BSATN.I128",
                "System.UInt128" => "SpacetimeDB.BSATN.U128",
                "SpacetimeDB.I128" => "SpacetimeDB.BSATN.I128Stdb",
                "SpacetimeDB.U128" => "SpacetimeDB.BSATN.U128Stdb",
                "SpacetimeDB.I256" => "SpacetimeDB.BSATN.I256",
                "SpacetimeDB.U256" => "SpacetimeDB.BSATN.U256",
                "System.Collections.Generic.List<T>" => $"SpacetimeDB.BSATN.List",
                "System.Collections.Generic.IEnumerable<T>" => $"SpacetimeDB.BSATN.List",
                // If we're here, then this is nullable *value* type like `int?`.
                "System.Nullable<T>" => $"SpacetimeDB.BSATN.ValueOption",

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