Description
The following create statement with an Enum in the class will fail with Invalid cast from 'System.Int64'.
I´m using sqlite, the query that fails looks like this
public async Task<long> CreateAsync(AppUser newUser)
{
await using var connection = new SqliteConnection(settings.ConnectionString);
const string sql =
$"""
INSERT INTO AppUser
(Username, Password, UserRole) VALUES
(
@{nameof(AppUser.Username)},
@{nameof(AppUser.Password)},
@{nameof(AppUser.UserRole)}
) RETURNING *;
""";
var insertedRows = await connection.QueryAsync<AppUser>(sql, newUser);
return insertedRows.FirstOrDefault()?.Id ?? -1;
}The Enum is mapped to an INTEGER column in Sqlite. Without AOT the mapping works just fine.
Adding a TypeHandler like this does not seem to work either
internal class UserRoleConverter : SqlMapper.TypeHandler<UserRole>
{
public override UserRole Parse(object value)
{
// theoretically this should fix it as casting to enums only works if it´s int32 afaik, but it never gets called
var int32Value = Convert.ToInt32(value);
return (UserRole) int32Value;
}
public override void SetValue(IDbDataParameter parameter, UserRole value)
{
parameter.Value = (int)value;
}
}
// Registered on startup
SqlMapper.AddTypeHandler(new UserRoleConverter());I am aware that this query in particular parsing the enum would be avoidable entierly, because I only need the Id back, but this would just be a fix for this one query and it would still be an issue for virtual everything else. It just happens to be the first thing that runs in virtually every single test I have.
There is this issue for regular dapper DapperLib/Dapper#259
So, does that mean if dapper AOT does not handle enums out of the box it just won´t be possible to make it work? I could probably work around this with a class that imitates enums and some explicit converters, but I would rather not.
Tried to create a simple wrapper class like this
public class UserRoleColumn(UserRole userRole)
{
public UserRole Value { get; set; } = userRole;
}with this type converter
public class UserRoleColumnConverter : SqlMapper.TypeHandler<UserRoleColumn>
{
public override void SetValue(IDbDataParameter parameter, UserRoleColumn? value)
{
ArgumentNullException.ThrowIfNull(value);
parameter.Value = (int) value.Value;
}
public override UserRoleColumn? Parse(object value)
{
var userRole = (UserRole) Convert.ToInt32(value);
return new UserRoleColumn(userRole);
}
}Also does not work throws No mapping exists from object type UserRoleColumn to a known managed provider native type in the same place.
On further inspection SqlMapper.AddTypeHandler is not yet AOT friendly. It breaks on publish so wether it´s used or not by the code generated does not even matter because you can´t register them.