orchardcore-content-definition-handlers

Orchard Core Content Definition Handlers & System-Defined Definitions

Intercept content definitions as they are built

You are an Orchard Core expert. IContentDefinitionHandler lets a module intercept and modify content type, part, and field definitions while they are being built, before they are cached. The primary use is injecting a part into a content type programmatically and marking types, parts, or fields as system-defined so users cannot remove or modify them through the admin UI or recipes. This complements — it does not replace — the IContentDefinitionManager migration APIs (see the orchardcore-content-types skill) used for ordinary, user-manageable definitions.

Guidelines

• Implement OrchardCore.ContentTypes.Events.IContentDefinitionHandler and register it with services.AddScoped<IContentDefinitionHandler, T>() in the module's Startup.
• The interface has four events; each receives a *BuildingContext exposing the definition record being built and its name:
  • ContentTypeBuilding(ContentTypeBuildingContext context) — a content type is being built.
  • ContentPartBuilding(ContentPartBuildingContext context) — a content part definition is being built.
  • ContentTypePartBuilding(ContentTypePartBuildingContext context) — a part is being attached to a type.
  • ContentPartFieldBuilding(ContentPartFieldBuildingContext context) — a field is being built on a part.
• Handlers run on every build, so guard with the stereotype, type name, or part name before mutating. Leave unrelated definitions untouched, and implement the events you do not need as empty methods.
• Mark a type, part, type-part, or field system-defined by writing a ContentSettings with IsSystemDefined = true into the record's Settings under the nameof(ContentSettings) key.
• Because the handler sets this at build time, it is not persisted to the stored definition; the capability is re-applied every time the definition is built, so it cannot be lost or edited away.
• A system-defined definition throws InvalidOperationException if code attempts to remove it through IContentDefinitionService, and the admin type/part editors render the Delete/Remove buttons as disabled.
• Read the flag on any definition with definition.GetSettings<ContentSettings>().IsSystemDefined.
• Always seal handler classes.