有什么办法可以订阅&吗?使用mvvm light Xamarin Forms发送通用类型类的消息传递中心 [英] Is there any way to subscribe & send messaging center for generic type class using mvvm light Xamarin Forms

问题描述

这就是我现在正在做的事情，有没有更好的解决方案可以使这种通用

That's how i am doing it right now, is there any better solution for making this generic

MessagingCenter.Send(this, "XYZ", "XYZ" + " Recieved");

MessagingCenter.Subscribe<MyService, string>(this, "XYZ", async (sender, arg) =>
{
     //TO-DO
});

推荐答案

我们如何使用Xamarin形式的消息传递中心发送消息: 这是我在下面的方法中使用的行:-

How we use to send message using messaging center in xamarin forms:- This is the line I have used In bellow method:-

  MessagingCenter.Send(this, typeof(T).Name, typeof(T).Name + " Recieved");

DatabaseService.cs ---我从"DatabaseService.cs"发送此消息，因此将其写在第一个参数中的第二个参数typeof(T)中以供参考.其中"T"是通用类.(T是Azure下载完成后的表名我正在发送消息以标识数据是从Azure服务器到达的，并保存在本地数据库中)，波纹管方法中的第二个参数也是typeof(T). "Receieved"和"Receieved"是我要传递的参数，用于标识是从存储中接收数据还是从存储中删除数据，以标识我对SQLite DB进行了哪种操作.

DatabaseService.cs --- I am sending this message from "DatabaseService.cs" so writting this for reference in first paramenter, in second parameter typeof(T).Name where "T" is generic class.(T is Azure Table name after downloading done I am sending message to identify the data is arrived from Azure server and saved in Local DB) , second paramenter in the bellow method is also typeof(T).Name which referes to key for which sender and receiver are subscribed and "Receieved" is arguments that I am passing to Identify that the data is received or deleted from store to identify which sort of operation I have performed on SQLite DB.

    /// <summary>
    /// Function to retrive Records from Azure Server and insert/Update those into localDB .
    /// </summary>
    /// <typeparam name="T">Table Name</typeparam>
    /// <param name="data">Records retrived from Azure Server that are being insrted to localDB.</param>
    /// <returns></returns>


        public async Task InsertDataToLocalDB<T>(List<T> data)
        {
            List<JObject> jDatas = new List<JObject>();
            for (int index = 0; index < data.Count; index++)
            {
                jDatas.Add(JObject.FromObject(data[index]));
            }
            try
            {
                await _store.UpsertAsync(typeof(T).Name, jDatas, true);  //_Store is MobileServiceSQLiteStore SQLite store
            }
            catch (Exception ww)
            {

                //throw;
            }


            MessagingCenter.Send(this, typeof(T).Name, typeof(T).Name + " Recieved");
        }

我们如何订阅消息:-

   MessagingCenter.Subscribe<DatabaseService, string>(this, "Notification", async (sender, arg) =>
            {
               //After Receiving Notifications from server Call Refresh Command
                await RefreshCommand.ExecuteAsync();
            });

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