加入擴展方法的語法

Question

我有以下c＃代碼。

IQueryable<Invoice> query = service.GetInvoices(); 

    query = query.Where(inv => inv.ProjectID == projectid); 
    query = query.Skip(pageIndex * pageSize).Take(pageSize); 

我想使用Join擴展方法將Join添加到「狀態」表。

找不到這個語法的很多例子。

你能幫忙嗎？

加入詳細資料以幫助您編寫代碼。

加入字段Status.ID到Invoice.invStatus

馬爾科姆

Answer 1

var query = 
    (
    from i in service.GetInvoices() 
    from s in service.GetStatuses() 
    where i.ProjectID == projectid && 
      s.ID == i.invStatus //"join" condition here 
      //add here any more where clausole you need 
    select i //you still need invoices returned? 
).Skip(pageIndex * pageSize).Take(pageSize); 

使用連接：

var query = 
    (
    from i in service.GetInvoices() 
    join s in service.GetStatuses() on s.ID equals i.invStatus 
    where i.ProjectID == projectid 
      //add here any more where clausole you need 
    select i //you still need invoices returned? 
).Skip(pageIndex * pageSize).Take(pageSize); 

如果我明白你的數據庫結構正確，我會去爲：

var query = 
    (
    from i in service.GetInvoices() 
    from s in i.Status  //get all the statuses associated to this invoice 
    where i.ProjectID == projectid 
      //add here any more where clausole you need 
    select i //you still need invoices returned? 
).Skip(pageIndex * pageSize).Take(pageSize);