Question

为什么db.Countries（）在以下场景中为空 - 1. CityController

private String readOpportunity(ServletInputStream in, String boundary, Logger logger) throws MultipartUploadException, IOException {

    logger.finer("Reading opportunity number");

    // Check for content disposition

    byte[] buffer = new byte[BUFFER_SIZE];
    int bytesRead = in.readLine(buffer, 0, BUFFER_SIZE);
    String line = new String(buffer, 0, bytesRead);

    if (!line.startsWith("Content-Disposition: form-data"))
        throw new MultipartUploadException("Missing or invalid content-disposition");

    // Get the opportunuity number

    if (line.indexOf("name=\"opportunity\"") == -1)
        throw new MultipartUploadException("Missing opportunity number");

    // Skip the blank seperator line

    bytesRead = in.readLine(buffer, 0, BUFFER_SIZE);
    if (bytesRead != 2)
        throw new MultipartUploadException("Missing seperator line");

    **bytesRead = in.readLine(buffer, 0, BUFFER_SIZE);**
    String opportunity = new String(buffer, 0, bytesRead);
    if (opportunity.length() < 3)
        throw new MultipartUploadException("Missing opportunity number");

    // Read ending boundary

    bytesRead = in.readLine(buffer, 0, BUFFER_SIZE);
    line = new String(buffer, 0, bytesRead);

    if (!line.startsWith(boundary))
        throw new MultipartUploadException("Missing or invalid ending boundary");

    // Remove trailing new line

    opportunity = opportunity.substring(0, opportunity.length() - 2);
    return opportunity;
}

ApplicationDbContext

[Authorize]
public class CityController : Controller
{        
    private ApplicationDbContext db = new ApplicationDbContext("CP");

    // GET: City/Create
    public ActionResult Create()
    {
        ViewBag.CountryId = new SelectList(db.Countries.ToList(), "CountryId", "Name");
        return View();
    }

国家/地区定义为 -

public class ApplicationDbContext : DbContext
{
    public ApplicationDbContext(string nameOrConnectionString)
    : base(nameOrConnectionString)
    {
    }

    internal IDbSet<Country> Countries { get; set; }

    ...
}

城市定义为 -

[Table("Country")]
public class Country
{
    #region Fields
    private ICollection<City> _cities;
    #endregion

    #region Scalar Properties
    public Guid CountryId { get; set; }
    public string Name { get; set; }
    public string CountryCode { get; set; }
    #endregion

    #region Navigation Properties
    public virtual ICollection<City> Cities
    {
        get { return _cities ?? (_cities = new List<City>()); }
        set { _cities = value; }
    }
    #endregion
 }

没有填充国家/地区表记录并将国家/地区返回为空的原因可能是什么？

Answer 1

在节省了几个小时之后，我注意到了国内属性的Access-modifier是内部的。我公开了，魔法发生了！虽然我对它的部分内容没有任何解释，但它有效。

public class ApplicationDbContext : DbContext
{
    public ApplicationDbContext(string nameOrConnectionString)
        : base(nameOrConnectionString)
    {
    }
    //internal IDbSet<Country> Countries { get; set; }
    public IDbSet<Country> Countries { get; set; }
    public IDbSet<City> Cities { get; set; }

谢谢大家。

ApplicationDbContext.EntityName（）返回null

1 个答案: