在 OData Web Api 控制器中使用 $expand 的 NullReferenceException

Question

环境：Net Core 3.1 Web Api，Microsoft.AspNetCore.OData 7.4.0-beta

我有一个运行良好的 OData api 控制器 CustomersController，但 $expand 总是返回 NullReferenceException。客户有一对多的联系人和地址。

这是动作方法的代码：

    [HttpGet]
    [ODataRoute]
    [EnableQuery]
    public IActionResult Get()
    {
        try
        {
            var customers = _context.Customers;

            _logger.LogInfo($"Returned {customers.Count()} customers from database.");

            return Ok(customers);
        }
        catch (Exception ex)
        {
            _logger.LogError($"Something went wrong inside Get customers action: {ex.Message}");
            return StatusCode(500, "Internal server error");
        }
    }

这是客户对象定义：

public class Customer : BaseEntity
{
    public Guid CustomerId { get; set; }

    [Required(ErrorMessage = "Name is required")]
    [StringLength(100, ErrorMessage = "Name can't be longer than 100 characters")]
    public string Name { get; set; }

    [StringLength(100, ErrorMessage = "Commercial name can't be longer than 100 characters")]
    public string CommercialName { get; set; }

    [Required(ErrorMessage = "Tax code is required")]
    [StringLength(25, ErrorMessage = "Tax code can't be longer than 25 characters")]
    public string TaxCode { get; set; }

    [StringLength(250, ErrorMessage = "Email can't be longer than 250 characters")]
    [EmailAddress]
    public string Email { get; set; }

    [StringLength(250, ErrorMessage = "Url can't be longer than 250 characters")]
    public string Url { get; set; }

    public ICollection<Contact> Contacts { get; set; }
    public ICollection<Address> Addresses { get; set; }
    public ICollection<Work> Works { get; set; }
}

DbContext 配置：

        // Table
        builder.ToTable("Customers");
        builder.HasKey(b => b.CustomerId);

        // Relationships
        builder.HasMany(b => b.Contacts)
            .WithOne(b => b.Customer)
            .HasForeignKey(b => b.CustomerId)
            .OnDelete(DeleteBehavior.Cascade);

        builder.HasMany(b => b.Addresses)
            .WithOne(b => b.Customer)
            .HasForeignKey(b => b.CustomerId)
            .OnDelete(DeleteBehavior.Cascade);

我有另一个控制器，但具有一对一的关系，并且此控制器可以与 $expand 一起正常工作，并在操作方法中使用相同的代码。

知道什么是失败的吗？ 问候

Answer 1

我发现这是 OData Web Api 库版本的问题。

这是问题：

问候