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Ryan 85095cfa85 [C#] Removes Query<TRow> and .Build() in favor of IQuery<TRow> (#4393 )

This fixes an issue with the C# implementation of Query Builder
requiring `Build()` to return a query, and the return type being
`Query<TRow>` rather than `IQuery<TRow>`.

# Description of Changes

1. Runtime/query-builder
* Removed the concrete `Query<TRow>` carrier type and every `.Build()`.
Query builder shapes now expose only `IQuery<TRow>` plus `ToSql()`.
* Ensured all builder entry points (tables, joins, filters) continue to
return `IQuery<TRow>`.
2. Source generator + bindings
* Updated `ViewDeclaration` analysis to treat any return type
implementing `SpacetimeDB.IQuery<TRow>` as a SQL view.
* Dispatcher generation now emits
`ViewResultHeader.RawSql(returnValue.ToSql())` . This eliminates a
`Query<TRow>` special-case.
3. Tests, fixtures, regression module
* Converted the C# query-builder unit tests, codegen fixtures, and
regression-test server views to call `ToSql()`/return `IQuery<TRow>`.
* Added coverage proving `RightSemiJoin` (and friends) still satisfy
`IQuery<TRow>`.
4. CLI templates & generated bindings
* Regenerated/edited C# template bindings so
`SubscriptionBuilder.AddQuery` accepts `Func<QueryBuilder,
IQuery<TRow>>` and captures SQL via `ToSql()`.

# API and ABI breaking changes

While technically API breaking, this actually brings the API closer to
the intended design.
* `Query<TRow>` has been removed from the public surface area; any
previous references (including `.Build()` and `.Sql`) must be replaced
with the builder instance itself plus `.ToSql()`.
* View methods must now return an `IQuery<TRow>` (or any custom type
implementing it) when producing SQL for the host.
* Generated C# client bindings now expect typed subscription callbacks
to produce `IQuery<TRow>`, aligning the client SDK with the new runtime
contract.

# Expected complexity level and risk

3 - Medium: Touches runtime, codegen, fixtures, and templates. Risk is
mitigated by parity with Rust semantics and comprehensive test updates,
but downstream modules must recompile to adopt the new interface.

# Testing

- [X] Built CLI and ran regression tests locally with removed `.Build()`
- [X] Ran `dotnet test .\sdks\csharp\tests~\tests.csproj -c Release`
with all tests passing
- [X] Ran `dotnet test
.\crates\bindings-csharp\Codegen.Tests\Codegen.Tests.csproj -c Release`
with all tests passing

2026-02-23 15:34:51 +00:00

Codegen.csproj

Version upgrade to 2.0 (#4252 )

2026-02-12 16:25:49 +00:00

Diag.cs

Move CaseConversionPolicy to public SpacetimeDB namespace (#4382 )

2026-02-20 22:21:46 +00:00

Module.cs

[C#] Removes Query<TRow> and .Build() in favor of IQuery<TRow> (#4393 )

2026-02-23 15:34:51 +00:00

README.md

SATS: Flatten AlgebraicType, getting rid of BuiltinType (#1559 )

2024-08-06 18:15:19 +00:00

README.md

SpacetimeDB.Codegen

This project contains Roslyn incremental source generators that augment types and tables with static methods for self-describing and registration. They look for different attributes to know which types to augment:

[SpacetimeDB.Type] - generates a GetSatsTypeInfo() static method that registers this type with the runtime and returns a TypeInfo object. It supports only structs for now to explicitly forbid infinitely recursive types and to make the implementation simpler, as it doesn't need to deal with type references - each table is registered as an entirely self-contained type together with its nested structs if any. This is unlikely to be a problem in common scenarios, but it will be optimised in the future.

All the nested fields will be added to the product type. Because it's not possible to implement static extension methods on 3rd-party types (including built-ins) in C#, the codegen is responsible for manually routing different types to their TypeInfo descriptors. See various static TypeInfo properties and helper methods on SpacetimeDB.BSATN.AlgebraicType (Runtime/AlgebraicType.cs) and routing logic in Utils.GetTypeInfo (Codegen/Utils.cs) for more details.

Also, for the same reason - absence of static extension methods in C# - the codegen expects that your struct, as well as any of its parents, is partial so methods can be added from extra source files generated by the codegen.
[SpacetimeDB.Type] - also supports emulation of tagged enums in C#. For that, the struct needs to inherit a marker interface SpacetimeDB.TaggedEnum<Variants> where Variants is a named tuple of all possible variants, e.g.:
```
[SpacetimeDB.Type]
partial record Option<T> : SpacetimeDB.TaggedEnum<(T Some, Unit None)>;
```
will generate inherited records Option.Some(T Some_) and Option.None(Unit None_). It allows you to use tagged enums in C# in a similar way to Rust enums by leveraging C# pattern-matching on any instance of Option<T>.
[SpacetimeDB.Table] - generates code to register this table in the FFI upon startup so that they can be enumerated by the __describe_module__ FFI API. It implies [SpacetimeDB.Type], so you must not specify both attributes on the same struct.

The fields can be marked with [SpacetimeDB.ColumnAttrs] and those will be detected by the codegen and passed on to the runtime as well. Example:
```
[SpacetimeDB.Table]
public partial struct Person
{
    [SpacetimeDB.Column(ColumnAttrs.Identity)]
    public int Id;
    public string Name;
}
```
[SpacetimeDB.Reducer] - generates code to register a static function as a SpacetimeDB reducer in the FFI upon startup and creates a wrapper that will parse SATS binary blob into individual arguments and invoke the underlying function for the __call_reducer__ FFI API.