Diagnostics

Facette emits compile-time diagnostics to help you catch configuration errors early. All diagnostics use the FCT prefix.

Reference

Code	Severity	Title	Description
FCT001	Error	Type must be partial	The type annotated with `[Facette]` must be declared as `partial`.
FCT002	Error	Include and Exclude conflict	Both `Include` and `Exclude` are specified on the same DTO, which is not allowed. Use one or the other.
FCT003	Error	Source type not found	The `SourceType` passed to `[Facette]` could not be resolved. Check that the type exists and is accessible.
FCT004	Warning	Property not found on source	A property name in `Include` or `Exclude` doesn't exist on the source type.
FCT005	Warning	MapFrom property not found	The `SourcePropertyName` in `[MapFrom]` doesn't exist on the source type.
FCT006	Warning	Circular reference	A nested DTO chain forms a cycle (e.g., A → B → A). Facette skips the cycle to prevent infinite recursion.
FCT007	Warning	Flattened path segment not found	A segment in a convention-flattened or dot-notation path couldn't be resolved on the source type.
FCT008	Warning	Convert method not found	The `Convert` method specified in `[MapFrom]` wasn't found as a static method on the DTO type.
FCT009	Warning	ConvertBack method not found	The `ConvertBack` method specified in `[MapFrom]` wasn't found as a static method on the DTO type.
FCT010	Error	Ambiguous nested DTO	Multiple DTOs target the same source type and Facette can't determine which to use. Specify `NestedDtos` on the parent DTO to resolve.
FCT011	Warning	Enum projection warning	An enum conversion (e.g., `.ToString()`) in a LINQ projection may not be translatable by EF Core.
FCT012	Info	Attribute reconstruction skipped	When `CopyAttributes = true`, an attribute on the source property couldn't be fully reconstructed and was skipped.
FCT013	Error	Conditional method invalid	The method referenced by `[MapWhen]` wasn't found, isn't `static`, isn't parameterless, or doesn't return `bool`.
FCT099	Warning	Internal generator error	An unexpected error occurred during code generation. Please report it.

Treating warnings as errors

You can promote Facette warnings to errors in your project file:

<PropertyGroup>
  <WarningsAsErrors>FCT004;FCT005;FCT006;FCT007;FCT008;FCT009;FCT011</WarningsAsErrors>
</PropertyGroup>

Suppressing diagnostics

To suppress specific diagnostics:

<PropertyGroup>
  <NoWarn>FCT011;FCT012</NoWarn>
</PropertyGroup>