Question

所以我遇到的问题是代码选择类别我需要更改排序顺序以按产品排序。名称然后按category.name。

但问题是我还是想选择一个类别，但我该怎么做首先按product.name排序，不要添加额外的连接或选择。

来自类别的类别选择category.name orderby category.Name // orderby category name

稍后在视图中我循环foreach（category.products）并传入category.product [i]以查看显示

但排序顺序错误，顺序始终是Category.Name 我如何先按Product.Name排序，再按Category.Name排序？ SelectMany会帮忙吗？我再次不想破坏选择我的查询的一部分，只是按订单排序。

类产品 { public string Name {get;组; } public int CategoryID {get;组; } }

类别 { public string Name {get;组; } public int ID {get;组; } }

//指定第一个数据源。静态列表类别=新列表（） { new Category（）{Name =＆＃34; Beverages＆＃34;，ID = 001}，新类别（）{名称=＆＃34;调味品＆＃34;，ID = 002}， new Category（）{Name =＆＃34; Vegetables＆＃34;，ID = 003}， new Category（）{Name =＆＃34; Grains＆＃34;，ID = 004}， new Category（）{Name =＆＃34; Fruit＆＃34;，ID = 005}
};

//指定第二个数据源。 static List products = new List（） { 新产品{Name =＆＃34; Cola＆＃34;，CategoryID = 001}，新产品{Name =＆＃34; Tea＆＃34;，CategoryID = 001}，新产品{Name =＆＃34; Mustard＆＃34;，CategoryID = 002}，新产品{Name =＆＃34; Pickles＆＃34;，CategoryID = 002}，新产品{Name =＆＃34; Carrots＆＃34;，CategoryID = 003}，新产品{Name =＆＃34; Bok Choy＆＃34;，CategoryID = 003}，新产品{Name =＆＃34; Peaches＆＃34;，CategoryID = 005}，新产品{Name =＆＃34; Melons＆＃34;，CategoryID = 005}， };

Answer 1

哦，我看到你查询了，格式很糟糕。

您需要order by Product.Name group by Category.Name

Answer 2

//LinqPad code

class Category
{
    public string Name { get; set; }
    public int ID { get; set; }
    public List<Product> products { get; set;}
}

class Product 
{
    public string Name { get; set; }
    public int ID { get; set; }
}


void Main()
{
        // Specify the second data source.
         List<Product> BevProducts = new List<Product>()
        {
            new Product{Name="ZCola"},
        };

        // Specify the third data source.
         List<Product> CondProducts = new List<Product>()
        {
            new Product{Name="Sugar"},
        };
      // Specify the first data source.
     List<Category> categories = new List<Category>()
        { 
            new Category(){Name="Beverages", ID=001, products=BevProducts},
            new Category(){ Name="Condiments", ID=002, products=CondProducts},

        };



        var sortedCats = categories.OrderBy(c => c.ID).ToList();

        foreach (var category in sortedCats)
        {
            //display category
            System.Console.Out.WriteLine(category.Name);

        //Assuming each category contains exactly one product in the list ie 1 to 1 relationship
// how can I sort by product.Name, so if ZCola comes before Sugar, ZCola's Category (Beverages) sorts before Condiments
// so in this Case Beverages, Condiments is the right order, because ZCola comes after Sugar.
            var  sortedProductsPerCategory = category.products.OrderBy(p => p.Name).ToList();

            foreach (var product in sortedProductsPerCategory)
            {
                    //display product
                    System.Console.Out.WriteLine("   " + product.Name);
            }
        }



}

Answer 3

class Category
{
    public string Name { get; set; }
    public int ID { get; set; }
    public List<Product> products { get; set;}
}

class Product 
{
    public string Name { get; set; }
    public int ID { get; set; }
}


void Main()
{
        // Specify the second data source.
         List<Product> BevProducts = new List<Product>()
        {
            new Product{Name="ZCola"},
        };

        // Specify the third data source.
         List<Product> CondProducts = new List<Product>()
        {
            new Product{Name="Sugar"},
        };
      // Specify the first data source.
     List<Category> categories = new List<Category>()
        { 
            new Category(){Name="Beverages", ID=001, products=BevProducts},
            new Category(){ Name="Condiments", ID=002, products=CondProducts},

        };



        var sortedCats = categories.OrderBy(c => c.products.Min(p => p.Name)).ToList();

        foreach (var category in sortedCats)
        {
            //display category
            System.Console.Out.WriteLine(category.Name);


            //Assuming each category contains exactly one product in the list ie 1 to 1 relationship
            // how can I sort by product.Name, so if ZCola comes before Sugar, ZCola's Category (Beverages) sorts before Condiments
            // so in this Case Beverages, Condiments is the right order, because ZCola comes after Sugar.
            var  sortedProductsPerCategory = category.products.OrderBy(p => p.Name).ToList();

            foreach (var product in sortedProductsPerCategory)
            {
                    //display product
                    System.Console.Out.WriteLine("   " + product.Name);
            }
        }



}

Linq按产品排序，但显示cateogires

3 个答案: