Map Guid values with EF Core in Cratis Arc

Cratis Arc converts .NET Guid values to strings for SQLite and leaves plain Guid mapping to the EF provider for PostgreSQL and SQL Server. When creating or changing a schema, check both the model conversion and the migration’s column declaration: Arc configures them separately.

Model conversion

Use BaseDbContext to apply ApplyGuidConversion to its relevant model types. For a context where you configure the mapping yourself, add AsGuid in OnModelCreating. Import Cratis.Arc.EntityFrameworkCore and Microsoft.EntityFrameworkCore:

modelBuilder.Entity<Customer>()
    .Property(customer => customer.Id)
    .AsGuid(Database.GetDatabaseType());

Here Customer.Id is a Guid property and Database belongs to the context.

Database	What AsGuid(databaseType) adds
SQLite	A Guid → string converter using ToString("D"), with Guid.Parse on reads
PostgreSQL	No additional conversion for a plain Guid; the EF provider supplies its mapping
SQL Server	No additional conversion for a plain Guid; the EF provider supplies its mapping

For a Guid-backed concept, AsGuid delegates to AsConcept. SQLite uses string storage for that converter too. Use ConceptAs<Guid> when the identifier needs a domain-specific name; it does not require Chronicle.

Migration declarations

GuidColumn and AddGuidColumn select these SQL type names independently of the model converter:

PostgreSQL	SQL Server	SQLite
UUID	UNIQUEIDENTIFIER	BLOB

On SQLite, the migration helper declares BLOB while AsGuid supplies strings. The declaration is neither a CHAR(36) mapping nor an instruction to serialize Guids as binary data. Review generated migrations and check reads and writes against existing data before changing either the schema or the value representation.

Arc’s built-in database detection covers the three providers above. For other EF providers, use application-owned registration and check the provider’s Guid mapping. This conversion does not configure indexes or collations.

For migration helper usage, continue to common column types. To define domain-specific identifiers, follow concept conversion.