using System;

using System.Linq;

using System.Collections.Generic;

using System.ComponentModel.DataAnnotations;

using System.ComponentModel.DataAnnotations.Schema;

​

using Microsoft.AspNetCore.OData.Query;

using Microsoft.AspNetCore.Http;

using Microsoft.EntityFrameworkCore;

using Microsoft.EntityFrameworkCore.Infrastructure;

using Microsoft.OData.ModelBuilder;

using Microsoft.OData.Edm;

using Microsoft.OData.UriParser;

​

using AutoMapper;

using AutoMapper.AspNet.OData;

using AutoMapper.Extensions.ExpressionMapping;

​

public static class Program

{

    public static void Main()

    {

        var model = CreateEdmModel();

        var mapper = BuildMapper();

        var db = new ClientContext();

        var opts = BuildQueryOptions<ArchiveDto>(model, "$select=id&$filter=Name eq 'Test'");

        var query = db.Archives.GetQuery(mapper, opts);

        Console.WriteLine("\n----- Select + Filter -----");

        Console.WriteLine(query.Expression.Print());

        query.ToList();

        opts = BuildQueryOptions<ArchiveDto>(model, "$select=id&$expand=Documents");

        query = db.Archives.GetQuery(mapper, opts);

        Console.WriteLine("\n----- Select + Expand -----");

        Console.WriteLine(query.Expression.Print());

        query.ToList();

        opts = BuildQueryOptions<ArchiveDto>(model, "$select=id&$expand=Documents($select=id;$filter=Name eq 'Test')");

        query = db.Archives.GetQuery(mapper, opts);

        Console.WriteLine("\n----- Expand(Select + Filter) -----");

        Console.WriteLine(query.Expression.Print());

        //this throws because the .Where is applied after the .Select for $expands.

        //Im assuming this also means the .Where expression isnt being translated either.

        //If you add Name to the Documents->$select makes the query work again.

        query.ToList();

    }

    private static ODataQueryOptions<T> BuildQueryOptions<T>(IEdmModel model, string? query=null)

    {

        var root = "http://localhost/odata";

        var entitySets = model.EntityContainer.Elements.OfType<IEdmEntitySet>();

        var entitySet = entitySets.Single(s => s.EntityType().FullTypeName() == "Default." + typeof(T).Name);   

        var setName = entitySet.Name;

        var parser = new ODataUriParser(model, new Uri(root), new Uri($"{root}/{setName}"));

        var path = parser.ParsePath();

        var req = BuildRequest(setName, query);

        var ctx = new ODataQueryContext(model, typeof(T), path);

        return new ODataQueryOptions<T>(ctx, req);

    }

    private static HttpRequest BuildRequest(string entitySet, string? query)

    {

        var req = new DefaultHttpContext().Request;

        req.Method = "GET";

        req.Scheme = "http";

        req.Host = new HostString("localhost");

        req.Path = $"/odata/{entitySet}"; // This should match your OData path

        if (query is not null)

        {

            req.QueryString = new QueryString("?" + query);

        }

        return req;

    }

    private static IMapper BuildMapper()

    {

        var config = new MapperConfiguration(cfg =>

        {

            cfg.AddExpressionMapping();

            var archiveMap = cfg.CreateMap<Archive, ArchiveDto>();

            archiveMap.ForAllMembers(o => o.ExplicitExpansion());

            var archiveRevMap = archiveMap.ReverseMap();

            archiveRevMap.ForAllMembers(o => o.ExplicitExpansion());

​

            var docMap = cfg.CreateMap<Document, DocumentDto>();

            docMap.ForAllMembers(o => o.ExplicitExpansion());

            var docRevMap = archiveMap.ReverseMap();

            docRevMap.ForAllMembers(o => o.ExplicitExpansion());

        });

        config.AssertConfigurationIsValid();

        return config.CreateMapper();

    }

    private static IEdmModel CreateEdmModel()

    {

        var builder = new ODataConventionModelBuilder();

        builder.EntitySet<ArchiveDto>("Archives");

        builder.EntitySet<DocumentDto>("Documents");

        return builder.GetEdmModel();

    }

}

​

public class Archive

{

    [Key]

    public required int Id { get; set; }

    public required string Name { get; set; }

    //navigations

    public List<Document>? Documents { get; set; }

}

​

public record ArchiveDto

{

    public required int Id { get; set; }

    public required string Name { get; set; }

    //navigations

    public List<DocumentDto>? Documents { get; set; }

}

​

public class Document

{

    [Key]

    public required int Id { get; set; }

    public required string Name { get; set; }

    public int ArchiveId { get; set; }

    //navigations

    [ForeignKey(nameof(ArchiveId))]

    public Archive? Archive { get; set; }

}

​

public record DocumentDto

{

    public required int Id { get; set; }

    public required string Name { get; set; }

    public int ArchiveId { get; set; }

    //navigations

    public ArchiveDto? Archive { get; set; }

}

​

public class ClientContext : DbContext

{

    public ClientContext() : base()

    {

        this.Database.EnsureDeleted();

        this.Database.EnsureCreated();

    }

​

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)

    {

        optionsBuilder.UseSqlite("Data Source=Test.db");

    }

    public DbSet<Archive> Archives { get; set; }

    public DbSet<Document> Documents { get; set; }

}