ForAttribute / AttributeMapper¶

ForAttribute is a fluent extension on IncrementalGeneratorInitializationContext that wraps Roslyn's ForAttributeWithMetadataName with a cleaner API.

Usage¶

By Generic Type¶

var models = context.ForAttribute<StrongIdAttribute>()
    .Map(static (ctx, _) => ExtractModel(ctx));

The fully qualified name is resolved automatically from the type.

By Type Object¶

Supports open generic types without backtick-arity syntax:

var models = context.ForAttribute(typeof(MyAttribute<>))
    .Map(static (ctx, _) => ExtractModel(ctx));

By String Name¶

var models = context.ForAttribute("MyApp.MyAttribute")
    .Map(static (ctx, _) => ExtractModel(ctx));

AttributeMapper Methods¶

Method	Description
`Map<TModel>(builder)`	Map each attributed symbol to a model. Model type is inferred.
`Where<TModel>(syntaxPredicate, builder)`	Map with a syntax node filter applied first.

Map¶

context.ForAttribute<RepoAttribute>()
    .Map(static (ctx, _) => new RepoModel(
        ctx.TargetSymbol.ContainingNamespace?.ToDisplayString(),
        ctx.TargetSymbol.Name));

Null returns are automatically filtered out — return null to skip a symbol.

Where (with Syntax Predicate)¶

context.ForAttribute<RepoAttribute>().Where(
    static (node, _) => node is ClassDeclarationSyntax,
    static (ctx, _) => ExtractModel(ctx)
);

The syntax predicate runs before the semantic model is loaded, providing a fast filter.

Null Handling¶

Both Map and Where automatically filter nulls from the output. If your builder returns null, the symbol is silently skipped:

.Map(static (ctx, _) =>
{
    if (ctx.TargetSymbol is not INamedTypeSymbol type)
        return null;  // Skipped — no output for this symbol

    return new MyModel(type.Name);
})