Question

我正在使用Dapper Multi Mapping来返回发票集合。每张发票都包含一组InvoiceItems。以下是模型。

public class InvoiceModel
{
    public int InvoiceId { get; set; }

    public string CustomerName { get; set; }

    public List<InvoiceItemModel> InvoiceItems { get; set; }
}

public class InvoiceItemModel
{
    public int InvoiceItemId { get; set; }

    public int InvoiceId { get; set; }

    public string ItemName { get; set; }

    public int Quantity { get; set; }
}

我发现如果我放置代码来获取数据并直接在控制器中映射对象，那么一切正常。但是，我想将此代码放入从控制器调用的服务中。当我将代码放在服务中时，代码不起作用。实际上，我甚至无法在作为服务一部分的方法中使用lambda扩展Distinct()或ToList()。

此代码有效 - 请注意它在API控制器中的正确性

public List<InvoiceModel> GetInvoiceTest(int invoiceId)
{
    using (IDbConnection db = new System.Data.SqlClient.SqlConnection(SqlDataAccess.LoadConnectionString("InvoiceDb")))
    {
        try
        {
            string sql = @"SELECT 
                            Invoice.InvoiceId,
                            Invoice.Customer AS CustomerName,
                            InvoiceItem.InvoiceItemId,
                            InvoiceItem.InvoiceId,
                            InvoiceItem.[Name] AS ItemName,
                            InvoiceItem.Quantity
                        FROM Invoice
                        LEFT JOIN InvoiceItem ON Invoice.InvoiceId = InvoiceItem.InvoiceId
                        WHERE Invoice.InvoiceId = " + invoiceId;

            var invoiceDictionary = new Dictionary<int, InvoiceModel>();

            var invoices = db.Query<InvoiceModel, InvoiceItemModel, InvoiceModel>(
                sql,
                (invoiceModel, invoiceItemModel) =>
                {
                    InvoiceModel invoiceEntry;

                    if (!invoiceDictionary.TryGetValue(invoiceModel.InvoiceId, out invoiceEntry))
                    {
                        invoiceEntry = invoiceModel;
                        invoiceEntry.InvoiceItems = new List<InvoiceItemModel>();
                        invoiceDictionary.Add(invoiceEntry.InvoiceId, invoiceEntry);
                    }

                    invoiceEntry.InvoiceItems.Add(invoiceItemModel);
                    return invoiceEntry;
                },
                splitOn: "InvoiceItemId").Distinct().ToList();

            return invoices;
        }
        catch (Exception ex)
        {
            Log.Error("", "Get Invoice Error", new { InvoiceId = invoiceId }, ex);
            throw new Exception("Error occured while trying to obtain Invoice", ex);
        }
    }
}

但是，如果我将相同的代码放在服务类中包含的静态方法中，我发现我无法使用.Distinct().ToList();。我发现我可以将扩展名更改为.AsList();，但结果会重复出现。

这是服务中的方法。

public static List<InvoiceModel> GetInvoices(int invoiceId)
{
  using (...)
  {
    // Same code as above starting with the using statement
    ...
    //splitOn: "InvoiceItemId").Distinct().ToList(); // Unavailable
    splitOn: "InvoiceItemId").AsList(); // Only option available
  }
}

是否与static的服务方法有关？

注意：我为帖子的长度道歉。我尝试尽可能多地配对它，但我觉得最好列出模型。

Answer 1

尝试以下方法

  var invoices = db.QueryAsync<InvoiceModel, InvoiceItemModel, InvoiceModel>(
                    sql,
                    (invoiceModel, invoiceItemModel) =>
                    {
                        InvoiceModel invoiceEntry;

                        if (!invoiceDictionary.TryGetValue(invoiceModel.InvoiceId, out invoiceEntry))
                        {
                            invoiceEntry = invoiceModel;
                            invoiceEntry.InvoiceItems = new List<InvoiceItemModel>();
                            invoiceDictionary.Add(invoiceEntry.InvoiceId, invoiceEntry);
                        }

                        invoiceEntry.InvoiceItems.Add(invoiceItemModel);
                        return invoiceEntry;
                    },
                    null,
                    null,
                    true,
                    splitOn: "InvoiceItemId",
                    999)
                    .Result
                    .Distinct()
                    .ToList();

谢谢

.Distinct（）和.ToList（）不适用于服务方法

1 个答案: