MSBuild properties

Five properties govern the generator. All go in a <PropertyGroup> in the project that holds your models — not in the application, unless that is the same project.

<PropertyGroup>
    <ValidationModules_Registration>ServiceCollection</ValidationModules_Registration>
    <ValidationModules_FieldNaming>SnakeCase</ValidationModules_FieldNaming>
    <ValidationModules_DataAnnotations>Ignore</ValidationModules_DataAnnotations>
    <ValidationModules_PatternPolicy>Error</ValidationModules_PatternPolicy>
</PropertyGroup>

ValidationModules_Registration

What registration code to emit alongside the validators.

Value	Effect
(unset)	auto — a module if IDependencyModule resolves, otherwise the extension
DependencyModules	always emit an IDependencyModule
ServiceCollection	always emit the Add…Validators() extension
None	emit no registration at all

Auto-detection probes the compilation for DependencyModules.Runtime.Interfaces.IDependencyModule. Set the property when DependencyModules arrives transitively and you do not want your validators in a module — None emits the validators and leaves the wiring to you.

See Registration and DI.

ValidationModules_FieldNaming

How a CLR property name becomes the field name in ValidationError.Field.

Value	PostalCode becomes
(unset) / CamelCase	postalCode
PascalCase	PostalCode
AsDeclared	PostalCode
SnakeCase	postal_code

[JsonPropertyName] and [Display(Name = …)] on the property both take precedence over this.

This is a build-time decision

Field names are baked into generated validators as string literals — nothing computes them per validation. Registering a different IValidationFieldNamer in DI does not rename a generated validator's errors; it only affects DescribedValidator<T> and the FluentValidation adapter.

If you use both engines, set this property and the registered namer to the same policy.

SnakeCase handles acronyms: HTTPStatusLine becomes http_status_line.

ValidationModules_DataAnnotations

Whether System.ComponentModel.DataAnnotations attributes are compiled.

Value	Effect
(unset)	compiled
Ignore	skipped, and each skipped constraint reports VM0010

The comparison is case-insensitive, and any value other than Ignore means "compile". Turning it off cannot silently unvalidate a model — a type whose only rules were DataAnnotations gets no validator, and every constraint reports.

Governs one vocabulary; native constraints are unaffected.

See DataAnnotations.

ValidationModules_PatternPolicy

Whether an inline [Pattern("…")] is acceptable.

Value	Effect
(unset)	Error if the project is AOT-facing, Allow otherwise
Allow	inline patterns accepted silently
Warn	VM0017 as a warning, constraint still emitted
Error	VM0017 as an error, constraint dropped

"AOT-facing" means PublishAot or IsAotCompatible is true. Both, deliberately: PublishAot is only ever true in the executable, so a class library holding your models would never see it, and the diagnostic would land on somebody else's publish instead of on the library's own build.

Set Error explicitly in a library that ships to AOT consumers.

See Patterns and regex.

Properties read but not owned

PublishAot / IsAotCompatible

Read as AOT signals for the pattern policy above. Setting IsAotCompatible on the project that holds your models is worth doing regardless — it turns on the trim analyzers for that project.

EmitCompilerGeneratedFiles

Not read by the generator, but the fastest way to see what it produced:

<PropertyGroup>
    <EmitCompilerGeneratedFiles>true</EmitCompilerGeneratedFiles>
</PropertyGroup>

Files land under obj/<Configuration>/<tfm>/generated/ValidationModules.SourceGenerator/…. Add an explicit CompilerGeneratedFilesOutputPath if you would rather they went somewhere else.

Worth enabling in a repository where the emitted code is part of what you review.

The assembly name

Not a property you set, but it names the registration method: AddMyAppValidators() is derived from AssemblyName, sanitized, because an assembly name is not necessarily a valid identifier.

AssemblyName	Registration method
MyApp	AddMyAppValidators()
My.App	AddMyAppValidators()
My-App	AddMy_AppValidators()
7Eleven	Add_7ElevenValidators()
(empty)	Generated

Diagnostic severity

Not MSBuild — .editorconfig. Every diagnostic is in category ValidationModules.Usage:

[*.cs]
dotnet_diagnostic.VM0004.severity = none
dotnet_analyzer_diagnostic.category-ValidationModules.Usage.severity = suggestion

Prefer silencing one id over the whole category. Several diagnostics are errors because the alternative is generated code that does not compile.