Cannot implicitly convert type 'Gridify.Paging<GridifyAdvancedDemo.Product>' to 'System.Linq.IQueryable<GridifyAdvancedDemo.Product>'

Question

I am working on a .NET 8 Web API project and have included the following NuGet packages:

<PackageReference Include="Gridify" Version="2.14.2" />
<PackageReference Include="Microsoft.EntityFrameworkCore" Version="8.0.8" />
<PackageReference Include="Microsoft.EntityFrameworkCore.InMemory" Version="8.0.8" />

While doing a Proof of Concept (POC) on Gridify, I referenced an article : https://medium.com/codenx/asp-net-core-web-api-with-gridify-d27627c81169 , but encountered the following error:

Cannot implicitly convert type 'Gridify.Paging<GridifyAdvancedDemo.Product>' to 'System.Linq.IQueryable<GridifyAdvancedDemo.Product>'. An explicit conversion exists (are you missing a cast?)

Here goes the code :

Program.cs

using GridifyAdvancedDemo;

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddSingleton<IProductRepository, ProductRepository>();
builder.Services.AddScoped<IProductService, ProductService>();
builder.Services.AddControllers();

var app = builder.Build();

app.UseHttpsRedirection();
app.UseAuthorization();
app.MapControllers();
app.Run();

Product.cs

namespace GridifyAdvancedDemo;

public class Product
{
    public int Id { get; set; }
    public string Name { get; set; }
    public decimal Price { get; set; }
    public string Category { get; set; }
}

ProductRepository.cs

namespace GridifyAdvancedDemo;

public interface IProductRepository
{
    IQueryable<Product> GetProducts();
}

public class ProductRepository : IProductRepository
{
    private readonly List<Product> _products;

    public ProductRepository()
    {
        // Sample data
        _products = new List<Product>
        {
            new Product { Id = 1, Name = "Product A", Price = 10.99m, Category = "Category1" },
            new Product { Id = 2, Name = "Product B", Price = 20.99m, Category = "Category2" },
            // Add more products
        };
    }

    public IQueryable<Product> GetProducts()
    {
        return _products.AsQueryable();
    }
}

ProductService.cs

using Gridify;

namespace GridifyAdvancedDemo;

public interface IProductService
{
    IQueryable<Product> GetFilteredProducts(GridifyQuery gridifyQuery);
}

public class ProductService : IProductService
{
    private readonly IProductRepository _productRepository;

    public ProductService(IProductRepository productRepository)
    {
        _productRepository = productRepository;
    }

    public IQueryable<Product> GetFilteredProducts(GridifyQuery gridifyQuery)
    {
        var products = _productRepository.GetProducts().Gridify(gridifyQuery);
        return products;
    }
}

ProductsController.cs

using Gridify;
using Microsoft.AspNetCore.Mvc;

namespace GridifyAdvancedDemo.Controllers;

[ApiController]
[Route("api/[controller]")]
public class ProductsController : ControllerBase
{
    private readonly IProductService _productService;

    public ProductsController(IProductService productService)
    {
        _productService = productService;
    }

    [HttpGet]
    public IActionResult GetProducts([FromQuery] GridifyQuery gridifyQuery)
    {
        var products = _productService.GetFilteredProducts(gridifyQuery);
        return Ok(products);
    }
}

Can anyone help me here with some code sample which will serve as a reference for my implementation?

Answer 1

The Gridify() method does not return an IQueryable<Product>; instead, it returns a Paging<Product>. Therefore, you should adjust the method signature to obtain the paging results. Alternatively, employ the appropriate methods for each specific operation, such as filtering, sorting, or paging.

    public IQueryable<Product> GetFilteredProducts(GridifyQuery gridifyQuery)
    {
        var products = _productRepository.GetProducts()
                 .ApplyFiltering(gridifyQuery)
                 .ApplyPaging(gridifyQuery)
                 .ApplyOrdering(gridifyQuery);
        return products;
    }

or if you need all three operations + IQuaryable result, you can use the ApplyFilteringOrderingPaging method

_productRepository.GetProducts().ApplyFilteringOrderingPaging(gridifyQuery)

my suggestion is:

public Paging<Product> GetFilteredProducts(GridifyQuery gridifyQuery)
{
    var products = _productRepository.GetProducts().Gridify(gridifyQuery);
    return products;
}