StronglyTypedIds

StronglyTypedIds helps to type entity identifiers for compile-time checking.

What problem are we solving?

Quite often, Guid, int, long, or string are used as identifiers for domain entities. Identifiers can be passed as arguments:

void AssignContractResponsible(Guid contractId, Guid employeeId);

In this example, 2 identifiers are used. You can only determine which one is which by the name of the argument. One day you can make a mistake and pass the identifiers in the wrong order. The problem is exacerbated if there are entities with similar names in the domain:

Contract и Contractor Order и OrderTemplate PriceList и PricePosition

Another example:

IDictionary<Guid, Contract> GetContractsByClients(IEnumerable<Guid> clientIds);

In this case, the client's identifier will probably act as the key of the dictionary. But we can't know this for sure, unless we look at the implementation.

Solution

The proposed solution is to pass not only the value of the identifier, but also the type of the identifiable entity.

So instead of:

void AssignContractResponsible(Guid contractId, Guid employeeId);

It becomes:

void AssignContractResponsible(GuidFor<Contract> contractId, GuidFor<Person> employeeId);

And instead of:

IDictionary<Guid, Contract> GetContractsByClients(IEnumerable<Guid> clientIds);

It will be:

IDictionary<GuidFor<Client>, Contract> GetContractsByClients(IEnumerable<GuidFor<Client>> clientIds);

License

This project is licensed under the MIT License - see the LICENSE.md file for details