如何将LINQ查询语法转换为方法语法？ （具有连接和多项选择）问题：+ 3个参数在任何地方都不会重载

Question

  

我试图通过Linq理解lambda表达式，但我为转换而苦恼。下面是可以正常工作的Linq Query语法。

var systemUsersPoor =
            (from customer in customers
                join distributor in distributors

                    on new { customer.Location }
                    equals new{ distributor.Location }

                where customer.Location == "UK" &&
                      customer.Location==distributor.Location &&
                      customer.Supplier == "MoneyShits" &&
                      distributor.Products == "ShittyCrappyCraps"

                orderby customer.Name
                select new
                {
                    customerName=customer.Name , customerLocation=customer.Location, customerSupplier=customer.Supplier,
                    distributorName=distributor.Name, distributorProducts=distributor.Products

                }).ToList();

  

然后在这里，我尝试将其转换为Linq方法语法失败。...直到.Where语句..表明它对我的字段（.location，.Supplier）没有定义时，所有方法都有效。和分销商

 var sysUserPoor2 = customers.Join       //from customer in customers Join 
        (
            distributors,                        //Join on distributors on customer.Location==distribution.Location
            customer=> customer.Location,        //Select the primary key (the first part of the "on" clause in an sql "join" statement
            distributor =>distributor.Location,  // Select the foreign key (the second part of the "on" clause)

            (customer, distributor) => new      //select statement
            {
                customerName = customer.Name,
                customerLocation = customer.Location,
                customerSupplier = customer.Supplier,
                distributorName = distributor.Name,
                distributorProducts = distributor.Products
            }
        )
            .Where
        (
             customer => (customer.customerLocation == "UK") &&
                         (customer.customerSupplier == "MoneyShits"),
            distributor => distributor.distributorProducts == "ShittyCrappyCraps",
                (customer, distributor) => (customer.customerLocation == distributor.Location)
            );

  

使用以下代码的查询有效，但我不知道如何以其他方式添加其余部分...：

.Where
        (
            customer => (customer.customerLocation == "UK") &&
                        (customer.customerSupplier == "MoneyShits")
        )

Answer 1

请尝试以下。

var systemUsersPoor = customers.Join(distributors, 
                customer => customer.Location, 
                distributor => distributor.Location,
                (customer, distributor) => new {customer, distributor})
                 .Where(x => x.customer.Location.Equals("UK") && 
                  x.customer.Location.Equals(x.distributor.Location) &&
                  x.customer.Supplier.Equals("MoneyShits") && 
                  x.distributor.Products.Equals("ShittyCrappyCraps"))
                  .OrderBy(x => x.customer.Name)
                  .Select(x => new
                 {
                    customerName = x.customer.Name,
                    customerLocation = x.customer.Location,
                    customerSupplier = x.customer.Supplier,
                    distributorName = x.distributor.Name,
                    distributorProducts = x.distributor.Products
                  }).ToList();