我如何更新我的WAMS表?

本文关键字：我的 WAMS 更新 何更新 | 更新日期: 2023-09-27 17:51:05

认为我需要做的更新WAMS记录是选择我想要的记录，然后修改我想要更改的所选记录的成员，最后在该记录上调用update，我有这个代码:

 public static async Task<bool> UpdateInvitation(string senderID, string readerName, string senderDeviceID)
 {
     try
     {
         IMobileServiceTable<WAMS_INVITATIONS> invitationsTable = App.MobileService.GetTable<WAMS_INVITATIONS>();
         MobileServiceTableQuery<WAMS_INVITATIONS> invitationRecordToUpdate =
               invitationsTable.Where(i => i.SenderID == senderID).
                                Where(i => i.ReaderName == readerName).
                                //Select(i => i.SenderDeviceID).
                                Take(1); // the query returns a List, but I only want 1 record (and it should only return 1)
         //invitationRecordToUpdate.SenderDeviceID = senderDeviceID; <-- "SenderDeviceID" not recognized
         await invitationsTable.UpdateAsync(invitationRecordToUpdate);
     }
     catch (Exception)
     {
         return false;
     }
     return true; // If no exception, assume record was inserted successfully
 }

…但它甚至无法编译。我得到的错误消息是:

1)*最好的重载方法匹配'Microsoft.WindowsAzure.MobileServices.IMobileServiceTable.UpdateAsync(phoneapp . data . wams_邀请函)'有一些无效参数*

…好的，但是什么是无效论证呢?

2)*参数1:不能转换"Microsoft.WindowsAzure.MobileServices.MobileServiceTableQuery

'到' phoneapp . data . wams_请柬'"*

我希望invationrecordtouupdate包含wams_invitation的所有成员/列，包括SenderDeviceID，但是没有…为什么?更重要的是，什么是规范的/首选的方法(没有双关语)更新WAMS记录?

更新

(没有双关语，尽管这个问题确实围绕着更新)

尝试使用建议的答案，这不会编译:

invitationsTable.Where(i => i.SenderID == senderID && i.ReaderName ==  readerName).SingleOrDefault
();

(在VS编辑器中，"SingleOrDefault"比毛主席的书还红)

…这:

await invitationsTable.UpdateAsync(invitationRecordToUpdate[0]);

…不能用[]对类型为'Microsoft.WindowsAzure.MobileServices.MobileServiceTableQuery'的表达式应用索引"

更新2

修改为:

IMobileServiceTable<TASLS_WAMS_INVITATIONS> invitationsTable = App.MobileService.GetTable<TASLS_WAMS_INVITATIONS>();

…: 

var invitationsTable = App.MobileService.GetTable<TASLS_WAMS_INVITATIONS>();

…这没有区别(也不应该有区别——所做的只是基于类型的构造函数使显式数据类型隐式。

所以我的代码现在是: 
public static async Task<bool> UpdateInvitation(string senderID, string readerName, string senderDeviceID)
{
    try
    {
        IMobileServiceTable<TASLS_WAMS_INVITATIONS> invitationsTable = App.MobileService.GetTable<TASLS_WAMS_INVITATIONS>();
        MobileServiceTableQuery<TASLS_WAMS_INVITATIONS> invitationRecordToUpdate =
            invitationsTable.Where(i => i.SenderID == senderID).
                             Where(i => i.ReaderName == readerName).
                             Take(1);
        if (null != invitationRecordToUpdate)
        {
            //await invitationsTable.UpdateAsync(invitationRecordToUpdate[0]); //both of these fail...
            //await invitationsTable.UpdateAsync(invitationRecordToUpdate);
        }
    }
    catch (Exception)
    {
        return false;
    }
    return true; // If no exception, assume record was inserted successfully
}

…正如你所看到的，我无法UpdateAsync，作为两种方式做它(注释掉)不编译。

我如何更新我的WAMS表?

像这样更新并显示错误:

public static async Task<bool> UpdateInvitation(string senderID, string readerName, string senderDeviceID)
    {
        try
        {
            IMobileServiceTable<TASLS_WAMS_INVITATIONS> invitationsTable = App.MobileService.GetTable<TASLS_WAMS_INVITATIONS>();
            var invitationRecordToUpdate =
                invitationsTable.Where(i => i.SenderID == senderID).
                                 Where(i => i.ReaderName == readerName).
                                 Take(1).ToListAsync();
                await invitationsTable.UpdateAsync(invitationRecordToUpdate[0]);
        }
        catch (Exception)
        {
            return false;
        }
        return true; // If no exception, assume record was inserted successfully
    }

编辑我刚刚检查了我的Windows应用程序。我使用这个，一切都很好:

private IMobileServiceTable<Rating> RatingTable =
         App.MobileService.GetTable<Rating>();
    var list = await RatingTable.Where(p => p.Id == sel_item.Id && p.User == user).ToListAsync();
    vat item=list[0];

返回列表时只使用第一个元素:

       await invitationsTable.UpdateAsync(invitationRecordToUpdate[0]);

你可以做出更好的linq:

invitationsTable.Where(i => i.SenderID == senderID && i.ReaderName ==  readerName).SingleOrDefault();

记得检查项目是否存在:

if(invitationRecordToUpdate!=null)
{//UPDATE }

SingleOrDefault方法:

返回序列的唯一元素，如果序列为空则返回默认值;如果序列中有多个元素，该方法将抛出异常。

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