CODEWITHSUNDEEP
nhibernateasp.net-mvc-4asp.net-web-api
Keith Nicholas
Keith Nicholas

Reputation: 44306

Querying using OData and asp.net MVC webapi against a NHibernate database

I doubt this is just specific to NHibernate. But I have code as follows....

public class ClientController : ApiController
    {
        // GET /api/<controller>
        public IQueryable<Api.Client> Get()
        {
            return Repositories.Clients.Query().Select(c => Mapper.Map<Client, Api.Client>(c));
        }

I basically want to Query the database using the Odata criteria.... get the relevant 'Client' objects, and the convert them to the DTO 'Api.Client'.

But... the code as is, doesn't work. Because NHibernate doesn't know what to do the with the Mapper.... It really wants the query to come before the .Select. But I'm not sure I can get the Odata Query first?

It will work if I do

return Repositories.Clients.Query().Select(c => Mapper.Map<Client, Api.Client>(c)).ToList().AsQueryable();

But that's a bit sucky as you have to get ALL the clients from the database to do the OData query on.

Is there anyway to get the "Select" to happen after the OData query? Or another way to approach this?

Upvotes: 1

Views: 2109

Answers (3)

janv8000
janv8000

Reputation: 1625

AutoMapper supports this scenario with the Queryable Extensions 

public IQueryable<Api.Client> Get() {
    return Repositories.Clients.Query().Select(c => Mapper.Map<Client, Api.Client>(c));
}

becomes 

public IQueryable<Api.Client> Get() {
    return Repositories.Clients.Query().ProjectTo<Api.Client>(mapper.ConfigurationProvider);
}

Upvotes: 0

labilbe
labilbe

Reputation: 3584

I did not test it yet but the Open Source project NHibernate.OData could be useful for you.

Upvotes: 1

Diego Mijelshon
Diego Mijelshon

Reputation: 52735

The problem is that you are trying to execute C# code (Mapper.Map) inside the NH call (that is translated to SQL)

You'd have to map Api.Client manually, or create a Mapper implementation that returns an Expression<Func<Client, Api.Client>> and pass it directly as a parameter to Select().

Even with that, I'm not sure if NHibernate will translate it. But you can try.

Upvotes: 0

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