使用實體框架更新列表項的最有效方式

Question

我們的用戶將擁有List<EmailRecords>集合，並且只有其中一個將標記爲(bool)IsPrimary = true。

我想編寫實體框架代碼來更新它。

事情是這樣的：

UPDATE dbo.EmailRecords 
SET IsPrimary = 1 
WHERE EmailRecordId = @RecordId 

UPDATE dbo.EmailRecords 
SET IsPrimary = 0 
WHERE EmailRecordId != @RecordId 
    AND ParentRecordId = @ParentRecordId 

我的目標是：

public class EmailRecords 
{ 
    public int EmailRecordId { get; set; } 
    public int ParentRecordId { get; set; } 
    public string EmailAddress { get; set; } 
    public bool IsPrimary { get; set; } 
} 

我怎樣才能做到這一點與實體框架？

我在想這樣做這樣的事情：

foreach (var thisRecord in profile.EmailRecords) 
{ 
    if (thisRecord.EmailRecordId == thisId) 
    { 
     thisRecord.IsPrimary = true; 
    } 
    else 
    { 
     thisRecord.IsPrimary = false; 
    } 
} 

db.SaveChanges(); 

有一個更清潔的方式做到這一點？

Answer 1

您是否在尋找C＃代碼？

foreach(var record in profile.EmailRecords) 
{ 
    record.IsPrimary = record.EmailRecordId == recordId; 
} 

Answer 2

使用您給出的示例模型。

public class EmailRecords 
{ 
    public int EmailRecordId { get; set; } 
    public int ParentRecordId { get; set; } 
    public string EmailAddress { get; set; } 
    public bool IsPrimary { get; set; } 
} 

您可以使用這種組合的LINQ和代碼來取消設置此主要行爲。

// Change this Int32 to match your @RecordId and @ParentRecordId. Possibly parameterize this entire code snippet into a method. 
Int32 recordIdToChange = 1; 
Int32 parentRecordIdToChange = 1; 

// Set the new primary. 
EmailRecords emailRecordToSetToPrimary = profile.EmailRecords.Where(cs => cs.EmailRecordId == recordIdToChange).FirstOrDefault(); 
if (emailRecordToSetToPrimary != null){ 
    emailRecordToSetToPrimary.IsPrimary = true; 
} 

// Only unset those records whose id does not match the new primary AND is currently set as a primary. 
List<EmailRecords> emailRecordsToUnsetFromPrimary = profile.EmailRecords.Where(cs => cs.EmailRecordId != recordIdToChange && cs.IsPrimary == true && cs.ParentRecordId == parentRecordIdToChange).ToList(); 
foreach (EmailRecords emailRecordToUnsetFromPrimary in emailRecordsToUnsetFromPrimary){ 
    emailRecordToUnsetFromPrimary.IsPrimary = false; 
} 

// Perform your save on the emailRecords list collection.