如何從與實體框架名稱相同的字段中加入實體框架字段子集

Question

我正在同時學習實體框架和Linq。我可以得到一個表到網格這個

List<object> boel; 

var query = from BillingOrderEntries boe in DM.BillingOrderEntries 
    select boe; 

boel = query.ToList(); 
dataGridView1.DataSource = boel; 

但我有困難試圖讓兩個表之間字段的子集。我認爲加入是正確的，因爲我已經看過幾個例子。

var boel = new[] { new { DateOfBirth= default(DateTime?), FirstName = "", LastName = "", AccessionField = "", Requisition = "" } }.ToList(); 

var query = from a in DM.Accessions 
    join boe in DM.BillingOrderEntries on a.Accession1 equals boe.Accession 
    orderby boe.LastName 
    select new { boe.DateOfBirth, boe.FirstName, boe.LastName, a.Accession, a.Requisition } 

boel = query.ToList(); 
dataGridView1.DataSource = boel; 

問題是Accession表中它有一個Accession列。我嘗試將該類的名稱更改爲AccessionTable，然後修改該屬性以在上下文類中反映此情況，但無論是這樣做還是我錯過了某處。然後我將Accession類中的屬性更改爲AccessionField。它編譯但不會運行：

LINQ to Entities不支持指定的類型成員'AccessionField'。僅支持初始化程序，實體成員和實體導航屬性。

我無法更改數據庫，但我可以更改任何可以使其工作的代碼。

Answer 1

你可以在選擇子句中使用別名爲字段，如下圖所示，注意這個例子只是嘲笑你引用模仿你的代碼，並演示瞭如何選擇條款混淆類：

修訂

/* Mock class */ 
    public class Accession 
    { 
     [Column("Accession")] 
     public string AccessionField { get; set; } 
     public string Requisition { get; set; } 
    } 

    /* Mock class */ 
    public class Billing 
    { 
     public string Accession { get; set; } 
     public string DateOfBirth { get; set; } 
     public string FirstName { get; set; } 
     public string LastName { get; set; } 
    } 

    /* Mock class */ 
    public class DataManager 
    { 
     public IEnumerable<Accession> Accessions { get; set; } 
     public IEnumerable<Billing> BillingOrderEntries { get; set; } 
    } 

    public static void Main(string[] args) 
    { 
     /* Start: Generate fake data */ 
     DataManager DM = new DataManager(); 
     DM.Accessions = new List<Accession>() { new Accession { AccessionField = "a1", Requisition="r1" }, new Accession { AccessionField = "a2", Requisition = "r2" } }; 
     DM.BillingOrderEntries = new List<Billing>() { new Billing { Accession = "a1", DateOfBirth = "01-01-2016", FirstName = "first1", LastName="last1" }, new Billing { Accession = "a2", DateOfBirth = "02-02-2016", FirstName = "first2", LastName = "last2" } }; 
     /* End: Generate fake data */ 

     var query = from a in DM.Accessions 
        join boe in DM.BillingOrderEntries on a.AccessionField equals boe.Accession 
        orderby boe.LastName 
        select new { 
         boe.DateOfBirth, 
         boe.FirstName, 
         boe.LastName, 
         a.AccessionField, 
         a.Requisition 
        }; 

     var boel = query.ToList(); 
    }