Question

我有一个如下所示的列表

List<Product> products = new List<Product>();

Add(new Product { ProductId = "abc", Type = "Normal", Status = "1" });
Add(new Product { ProductId = "def",  Type = "Normal", Status = "2"  });
Add(new Product { ProductId = "ghi",  Type = "VIP" , Status = "1" });
Add(new Product { ProductId = "jkl",  Type = "Group", Status = "1" });

public Product Add(Product item)
{
    if (item == null)
    {
        throw new ArgumentNullException("item");
    }
    products.Add(item);
    return item;
}

我想算得像：

类型：正常计数：2 类型：VIP数量：1 类型：组数：1

来自以下位置的早期帮助 Unique object counts are not getting counted in form of String but char

我写了代码

var groups = products.GroupBy(x => new { x.Type, x.Status }).Select(g => string.Format("Type: {0} Count: {1}", g.Key, g.Count()));

当我跑到上面时，我得到的文字分组如下

System.Linq.Enumerable + WhereSelectEnumerableIterator 2[System.Linq.IGrouping 2 [＆LT;＆GT; f__AnonymousType0`2 [System.String，System.Int32]，LocalServer.Product]，System.String] ##

不确定如何解决，或者我做错了什么。

Answer 1

您需要使用组键属性的“类型”属性来获取类型名称，因为您要按新的匿名类型进行分组。

var groups = products.GroupBy(x => new { x.Type, x.Status }).Select(g => string.Format("Type: {0} Count: {1}", g.Key.Type, g.Count()));

Answer 2

这可以解决您的问题。

List<Product> products = new List<Product>();
products.Add(new Product { ProductId = "abc", Type = "Normal", Status = "1" });
products.Add(new Product { ProductId = "def",  Type = "Normal", Status = "2"  });
products.Add(new Product { ProductId = "ghi",  Type = "VIP" , Status = "3" });
products.Add(new Product { ProductId = "jkl",  Type = "Group", Status = "1" });

IEnumerable<string> groupedProducts = products.GroupBy(product => product.Type)
                                              .Select(grouping => string.Format("Type: {0} Count: {1}", grouping.Key, grouping.Count())); 

foreach (var groupedProduct in groupedProducts)
{
    Console.WriteLine(groupedProduct);
}

问题在于您尝试按多个属性进行分组，因为您只想按Type计算，使用.GroupBy(product => product.Type)，然后使用.Select()投影结果以任何你想要的方式。

唯一对象计数显示系统文本

2 个答案: