How to map a C# enum to a PostgreSQL enum type?

[abirmkj]

I have a C# class Sample, one of whose properties is an enum, TargetType. I have a corresponding table samples defined in a PostgreSQL database, along with a matching enum type, targettypes.

With Dapper.FastCRUD, I can retrieve records from the table successfully. However, I get an error during insertion:

Npgsql.PostgresException (0x80004005): 42804: column "target_type" is of type targettype but expression is of type integer

How do I tell Dapper.FastCRUD to map the C# enum TargetType to PostgreSQL targettype for inserts?

In my C# code, I've defined:

// Map the C# enum 'TargetType' to PostgreSQL enum 'targettype'
// Allows Npgsql to insert and retrieve the fields with correct type-casting / boxing
Npgsql.NpgsqlConnection.MapEnumGlobally<TargetType>("public.targettype");  

Dapper.FastCrud.OrmConfiguration.DefaultDialect = Dapper.FastCrud.SqlDialect.PostgreSql;

When using only Npgsql (and no ORM), I can successfully insert as follows:

using (var writer = conn.BeginBinaryImport(sql))
{
    foreach (Sample sample in entities)
    {
        writer.StartRow();
        ...
        writer.Write(sample.TargetType); // <--- mapped to column 'target_type'
        ...
    }
}

[MoonStorm]

No DB-CLR type conversions occur at the level of this library. We're passing and retrieving data through Dapper.

[abirmkj]

Thanks for the clarification @MoonStorm .
Could you point me to some resources that would help resolve this issue?

[MoonStorm]

While in this particular case I'd recommend sticking to the basic primitive types (ie use an integer instead of an enum), I've started a section in the wiki about value mappings here. We can expand it later with other examples.