Proposal - ProjectToType as NonGeneric

[JMPSequeira]

Hello,

IMHO it would add great value to your library if one could use ProjectoToType with the following:

IEnumerable<object> result = someDbContext.SomeDbSet.ProjectToType(typeof(SomeProjectionType));

This is already possible with the Adapt method.

This would allow for, i.e., dynamic api requests mapped straight in the projection.

Let me know if you think this to be useful?

[chaowlert]

I think IEnumerable<Poco> can be assigned to IEnumerable<object> right?

If your type is dynamic, for now Mapster doesn't support your use case. The closest, you can call config.CreateMapExpression to create LambdaExpression and create query from there.

[JMPSequeira]

No dynamics, I expressed the idea poorly.

I meant projection to types unknown at design time in order to provide flexibility and segregation between the query and the projection.

The example was also expressed poorly :) 2 for 2 I'm on a roll.

Imagine a scenario where you have a web api that performs a query and the return result can be any of the possible projections for the type being queried, something like:

public ActionResult Get(int projectionToken)
{
    Type projectionType = GetProjectionType(projectionToken);

    if(projectionType != null)
    {
        IEnumerable<object> result = someDbContext.SomeDbSet.ProjectToType(projectionType);

        return Ok(result);
    }
    return BadRequest();
}

If I understood correctly your idea would be:

var config = new TypeAdapterConfig().NewConfig(typeof(Source), typeof(Destination));

var lambda = config.Config.CreateMapExpression(new TypeTuple(typeof(Source), typeof(Destination)), MapType.Projection);

var projection = someDbContext.SomeDbSet.AsQueryable().Provider.CreateQuery(lambda);

var result = projection.Cast<object>().ToList();

This is what I envision to be under the hood :)

[JMPSequeira]

@chaowlert 👍