Block entity creation with an internal constructor

You may want to prevent application developers from creating new instances of certain entity types. You will need a "defense in depth" on both client and server to block the determined developer. In this topic we suggest that you block entity construction by making all constructors internal.

Fixed-set entity types

In every application there are "fixed-set" entity types. The number of states in the USA is fifty and that is not expected to change. If U.S. states are modelled as entities, you want to make it difficult to add a new state by accident.

It's a good idea to add a save interceptor rule [LINK] that rejects any client's attempt to save a change to a U.S. State or to alter the set of U.S. states. 

Unfortunately, a developer won't know that changes are forbidden until runtime when the application throws an exception. If you make the entity difficult to construct in the first place, the developer won't be tempted to make a mistake.

Write an internal default constructor

Consider writing an internal default constructor. Make all other constructors internal as well.

Leave a back-door

Make it difficult to create an entity but not impossible. You don't want to query for test entities and you can't query for design entities. You need a back-door to create them in memory and make it look like you queried for them - a technique covered elsewhere [LINK]. The internal constructor may be sufficient. 

Alternatively, you can add a static CreateForTest method to the entity class that is clearly limited in intent. Surround it in compiler directives to ensure it doesn't show up in your release builds.