Я разработал приведенный ниже класс, который подключает слушателя для одного или нескольких запросов, это может быть не лучшим решением, но оно работает.
Таким образом, он создаст объект для каждого триггера, который может, например, использоваться для запуска SinalR. Вам просто нужно запустить Dependency и класс SqlDependencyHelper в Global.asax, и все будет храниться в SqlDataManagement, как, если триггер является обновлением или удалением и какой идентификатор изменился.
Третье поле в SELECT, которое называется ReferenceItem, можно использовать, чтобы узнать, произошел ли триггер из-за обновления, поэтому я использовал столбец DateTime DB с именем lastChanged, чтобы узнать, какая строка обновлена.
Все запросы должны быть из списка и в формате ниже
Выбрать образец
@ "ВЫБЕРИТЕ 'PreStartPhotos' как QueryReferenceName, [id], '' как ReferenceItem FROM [dbo]. [PreStartPhotos]"
Классы
using System;
using System.Collections.Generic;
using System.Configuration;
using System.Data.SqlClient;
using System.IO;
using System.Linq;
namespace WebAPI.Helpers
{
public class SqlDependencyHelper
{
private static SqlDependency _dep;
private static readonly string SqlConnectionString = ConfigurationManager.ConnectionStrings["CONNECTION_STRING"].ConnectionString;
private static Dictionary<string, Dictionary<string,string>> _tableData = new Dictionary<string, Dictionary<string,string>>();
~SqlDependencyHelper()
{
SqlDependency.Stop(SqlConnectionString);
}
/// <summary>
/// This method must start via the Global.asax to initialize the SQL Dependency's OnChange trigger. Example:
/// SqlDependency.Start(ConfigurationManager.ConnectionStrings["CONNECTION_NAME"].ConnectionString);
/// SqlDependencyHelper.RegisterSqlNotification().
/// This method will be recalled by the <see cref="OnDataChange"/> every time that a message is received from the SQL Server.
/// </summary>
/// <param name="notificationType">Notification type received by the SQL Notification using the <see cref="OnDataChange"/> method</param>
public static void RegisterSqlNotification(SqlNotificationInfo notificationType = SqlNotificationInfo.Invalid)
{
try
{
using (var conn = new SqlConnection(SqlConnectionString))
{
// Start the SQL Dependency with the commands to keep watching the database
conn.Open();
var cmd = conn.CreateCommand();
cmd.CommandText = string.Join("; ", Global.SqlDependencyList);
_dep = new SqlDependency(cmd);
_dep.OnChange += OnDataChange;
// Load the select that has been returned from the database
var dataResult = cmd.ExecuteReader();
var dumpData = new Dictionary<string, Dictionary<string,string>>();
do
{
// Load all information using the sql command provided
while (dataResult.Read())
{
if (dataResult[0] == DBNull.Value || dataResult[1] == DBNull.Value || dataResult[2] == DBNull.Value) continue;
if(!dumpData.ContainsKey(dataResult[0].ToString()))
dumpData.Add(dataResult[0].ToString(),new Dictionary<string, string> { {dataResult[1].ToString(),dataResult[2].ToString()} });
else
dumpData[dataResult[0].ToString()].Add(dataResult[1].ToString(),dataResult[2].ToString());
}
// As it may have more than one query, keep looping until it load all selects
} while (dataResult.NextResult());
// Database diff that point all changes
// Use this var to inject all changes within a method that triggers the business workflow like a SignalR method
var dbTracker = (from table in _tableData where dumpData.ContainsKey(table.Key) select new SqlDataManagement(table.Key, table.Value, dumpData[table.Key], notificationType)).ToList();
// Take a snapshot of the data that has been loaded to be used next time
_tableData = dumpData;
dataResult.Dispose();
cmd.Dispose();
}
}
catch (Exception e)
{
// As this module is executed within the Global that doesn't handle exceptions properly
// An exception controller had to be added to avoid the application to stop working if an exception is raised
// An email will be send to alert everyone
const string module = "SQLDependency";
var emailHtml = File.ReadAllText($"{Global.DefaultEmailTemplateFolder}/exception_alerts.html").Replace("{pathName}",module)
.Replace("{dateUtcTime}",CommonHelper.FromUtcToLocalTime(TimeZoneInfo.FindSystemTimeZoneById(Global.DefaultTimeZone)).ToString("F"))
.Replace("{exceptionMessage}",e.Message)
.Replace("{exceptionStackTrace}",e.StackTrace)
.Replace("{exceptionFull}",e.ToString());
var emails = new List<string> {Global.DefaultEmailAlerts};
AmazonApiHelper.SendEmailRaw(emails, $"Exception Alert: {module}", emailHtml);
}
}
/// <summary>
/// OnChange function that receives the trigger from the SQL broker.
/// It gets the broker information and call the <see cref="RegisterSqlNotification"/> again to re-attach the broker.
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private static void OnDataChange(object sender, SqlNotificationEventArgs e)
{
var dep = sender as SqlDependency;
dep.OnChange -= OnDataChange;
RegisterSqlNotification(e.Info);
}
}
/// <summary>
/// Object used to map changes to a individual query executed by the SqlDependency.
/// </summary>
public class SqlDataManagement
{
public SqlDataManagement(string queryReferenceName, Dictionary<string,string> objectsOldFromDb, Dictionary<string,string> objectsNewFromDb, SqlNotificationInfo sqlNotificationInfo)
{
QueryReferenceName = queryReferenceName;
ObjectsNewFromDb = objectsNewFromDb;
ObjectsOldFromDb = objectsOldFromDb;
ObjectsStatus = new Dictionary<string, SqlNotificationInfo>();
// Check if any id has been removed or added
var newObjectIds = objectsNewFromDb.Keys.ToList();
var oldObjectIds = objectsOldFromDb.Keys.ToList();
var newIds = newObjectIds.Except(oldObjectIds).ToList();
var removedIds = oldObjectIds.Except(newObjectIds).ToList();
// Update the ObjectsStatus with all new and removed ids
foreach (var newId in newIds)
{
ObjectsStatus.Add(newId,SqlNotificationInfo.Insert);
}
foreach (var removedId in removedIds)
{
ObjectsStatus.Add(removedId,SqlNotificationInfo.Delete);
}
// Check if an object has been inserted or deleted to update the status of the transaction
if (!objectsOldFromDb.All(objectsNewFromDb.Contains) || objectsOldFromDb.Count != objectsNewFromDb.Count)
{
SqlNotificationInfo = sqlNotificationInfo;
}
else
{
SqlNotificationInfo = SqlNotificationInfo.Unknown;
}
// Check if any item has been changed since the last update
foreach (var objectNew in ObjectsNewFromDb)
{
// Check if the item matches in both old and new tables
if (!ObjectsOldFromDb.ContainsKey(objectNew.Key)) continue;
// Ignore if the object is the same
if (ObjectsOldFromDb[objectNew.Key] == objectNew.Value) continue;
// Change the notification to update and add the id to the UpdatedList
SqlNotificationInfo = SqlNotificationInfo.Update;
ObjectsStatus.Add(objectNew.Key,SqlNotificationInfo.Update);
}
// Add all unchangedIds to the final object
var unchangedIds = oldObjectIds.Except(ObjectsStatus.Keys).ToList();
foreach (var unchangedId in unchangedIds)
{
ObjectsStatus.Add(unchangedId,SqlNotificationInfo.Unknown);
}
}
/// <summary>
/// The first field of every SQL Dependency command must be the Query Reference name.
/// It will be used as reference and help any method that rely on this result to use the data.
/// E.g. SELECT 'PreStartPhotos' as QueryReferenceName, [id], '' as ReferenceItem FROM [dbo].[PreStartPhotos]
/// </summary>
public string QueryReferenceName { get; set; }
/// <summary>
/// Contain all new and old ids plus all ids that have been updated since the last trigger.
/// SqlNotificationInfo.Unknown -> hasn't changed since last trigger.
/// SqlNotificationInfo.Update -> the id has been updated.
/// SqlNotificationInfo.Delete -> the id has been deleted.
/// SqlNotificationInfo.Insert -> the id has been inserted.
/// </summary>
public Dictionary<string,SqlNotificationInfo> ObjectsStatus { get; set; }
/// <summary>
/// Data from the last trigger
/// </summary>
public Dictionary<string,string> ObjectsOldFromDb { get; set; }
/// <summary>
/// Data that has been captured from the recent trigger
/// </summary>
public Dictionary<string,string> ObjectsNewFromDb { get; set; }
/// <summary>
/// If any update, delete or insert is detected within the ObjectStatus, this var will be true
/// </summary>
public bool HasAnyChange => ObjectsStatus.Any(p=> p.Value != SqlNotificationInfo.Unknown);
/// <summary>
/// Information about the SQL notification that triggered this update.
/// SqlNotificationInfo.Unknown is used if nothing has happened.
/// </summary>
public SqlNotificationInfo SqlNotificationInfo { get; set; }
}
}