What causes "view schema should validate for query builder codegen" in clockworklabs/SpacetimeDB?

Validate the module with `spacetime build` and address the reported view validation errors before generating bindings.

view schema should validate for query builder codegen

Error message

view schema should validate for query builder codegen

What it means

Panic in SpacetimeDB's Unreal C++ query-builder code generation, mirroring error 601 but for views. For each `view` in the module, `TableSchema::from_view_def_for_codegen(module, view).validated()` must return a valid schema; otherwise `expect("view schema should validate for query builder codegen")` panics. It signals that a view definition passed module building but fails downstream schema validation.

Source

Thrown at crates/codegen/src/unrealcpp.rs:3294

            cols_struct: format!("F{module_prefix}{source_pascal}Cols"),
            ix_cols_struct: format!("F{module_prefix}{source_pascal}IxCols"),
            fields,
            singleton_indexed_fields,
            source_name: table.name.deref().to_string(),
            source_pascal,
            can_be_lookup: !table.is_event,
        });
    }

    for view in iter_views(module) {
        let product_type = module.typespace_for_generate()[view.product_type_ref]
            .as_product()
            .expect("query builder source should be a product type");
        let row_struct = format!("F{}Type", type_ref_name(module_prefix, module, view.product_type_ref));
        let source_pascal = view.accessor_name.deref().to_case(Case::Pascal);
        let schema = TableSchema::from_view_def_for_codegen(module, view)
            .validated()
            .expect("view schema should validate for query builder codegen");

        let singleton_indexed_fields = singleton_indexed_fields_for_schema(&schema, product_type);

        let fields = product_type
            .elements
            .iter()
            .map(|(field_name, field_ty)| {
                (
                    field_name.deref().to_string(),
                    field_name.deref().to_case(Case::Pascal),
                    cpp_ty_fmt_with_module(module_prefix, module, field_ty, module_name).to_string(),
                    field_ty.clone(),
                )
            })
            .collect::<Vec<_>>();

        source_metas.push(QueryBuilderSourceMeta {
            row_struct,

View on GitHub (pinned to 6dee26c6ef)

Solutions

Validate the module with `spacetime build` and address the reported view validation errors before generating bindings.
Temporarily remove views from the module and regenerate to isolate the failing view; fix or simplify its definition.
Match `spacetime` CLI and `spacetimedb-std` module SDK versions to the same release.
File an issue with the module schema if a view that builds successfully still panics during query-builder codegen.

Example fix

// before: view derived from a table shape that fails schema validation
view HighScores { SELECT score FROM Player WHERE score > 1000 }

// after: project plain scalar columns that validate cleanly
view HighScores { SELECT name, score FROM Player WHERE score > 1000 }

Defensive patterns

Strategy: validation

Validate before calling

for view in iter_views(module) {
    let schema = TableSchema::from_view_def_for_codegen(module, view);
    if !schema.validated() { /* report and abort before query-builder codegen */ }
}

Prevention

Validate views before generate, not after the panic.
Test view changes with generate in CI for every module change.
Avoid projecting types the target binding language documents as unsupported.

When it happens

Trigger: Running `spacetime generate` for Unreal C++ bindings on a module containing a view whose derived schema does not validate — e.g. a view over a table with incompatible index definitions, or a projection whose element types the validator rejects. `iter_views(module)` iterates all views, so one bad view aborts generation for the whole module.

Common situations: Adding new views after upgrading the SpacetimeDB SDK; views that worked under older validation rules; modules with complex projections or filters that the codegen schema layer cannot represent; mismatched CLI/SDK versions.

Understand the failure class

Background: Schema validation failed / invalid input schema: payload rejected because its shape doesn't match the expected schema — this error's family across 28 libraries.

Related errors

AI-assisted analysis of clockworklabs/SpacetimeDB@6dee26c6ef (2026-08-20). Data as JSON: /api/errors/e2b13847f382d5e6. Report an issue: GitHub.