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c# - 如何查询/将数据转换为所需的格式

问题描述

我想知道是否有人可以帮助我将以下数据（来自数据库）转换为 List。：

洛里德 产品编号 数量类型 数量 是评论 评论
1 4090 3 2 F
1 4153 3 1 F
1 4153 3 1 F
1 4153 3 1 F
1 4153 3 1 F
1 4153 3 1 F
1 31068 3 2 F
1 31069 3 2 F
1 31173 3 2 F
2 17 0 1.000 F
2 150 3 6.000 F
2 216 3 6.000 F
2 278 2 1.020 F
2 398 2 1.125 F
2 398 2 1.090 F
2 398 2 0 吨 必须成熟
2 431 2 3.000 F
2 436 3 1.000 F
2 446 0 1 F
2 446 2 3.045 F
2 451 3 2.000 F
2 457 3 1.000 F
2 458 3 4.000 F
2 478 3 1.000 F
2 510 2 1.140 F
2 518 3 3.000 F
2 518 3 4.000 F
2 550 2 1.170 F
2 550 3 1.000 F

进入下面的对象。

public class View
{
  public List<LorryLoading> Report
}

public class LorryLoading
{
  public int LorryId
  public List<Product> Product
}

public class Product
{
  public int ProductId
  public decimal Qty0 sum(Quantity) WHERE QtyType = 0
  public decimal Qty2 sum(Quantity) WHERE QtyType = 2
  public decimal Qty3 sum(Quantity) WHERE QtyType = 3
  public List<string> Comments
}

是否可以使用单个投影？在分配列表时遇到问题。

另外，我可以学习这种转换的任何链接？到目前为止，我发现的示例相当简单或解释不清。

标签： c#linqlinq-to-sql

解决方案

您要问的是转换，因此没有简单的投影。您可能可以使用一个超级复杂的语句来做到这一点，这将使您的同事在必须维护时更换工作:) 我的建议是不要试图给校园留下深刻印象，而是专注于干净的代码：

var lorryLoadingReport = new List<ReportData>();
//Presume you already have data into a transport object and know how to read that, as it wasn't your question

var view = new View
{
    Report = new List<LorryLoading>()
};
var listOf = new List<Product>();
        
//Lets not over complicate our mind, just keep it simple, let's get the products and the lorries
var productsList = lorryLoadingReport.Select(x => x.ProductId).ToList();
var lorriesList = lorryLoadingReport.Select(x => x.LorryId).ToList();
foreach (var lorry in lorriesList)
{
    //We'll need an entry even if the list will be empty
    var lorryLoading = new LorryLoading
    {
        LorryId = lorry,
        Product = new List<Product>()
    };

    //Get the respective subset
    var lorryLoadingReportPerLorry = lorryLoadingReport.Where(l => l.LorryId == lorry);
    if (lorryLoadingReportPerLorry.Any())
    {
        foreach (var productId in productsList)
        {
            //And add a product with all 4 sums iteratively
            var p = new Product
            {
                ProductId = productId,
                Comments = new List<string>()
            };
            var commentsList = lorryLoadingReport.Where(x => x.ProductId == productId && x.IsComment == "t").Select(s => s.Comment).ToList();
            if(commentsList.Any())
                p.Comments.AddRange(commentsList);
            p.Qty0 = lorryLoadingReport.Where(x => x.Qty == 0).Sum(y => y.Qty);
            p.Qty2 = lorryLoadingReport.Where(x => x.Qty == 2).Sum(y => y.Qty);
            p.Qty3 = lorryLoadingReport.Where(x => x.Qty == 3).Sum(y => y.Qty);

            lorryLoading.Product.Add(p);
        }
    }    
    view.Report.Add(lorryLoading);
}

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