[英]A Command Is Already In Progress
我正在嘗試為我正在開發的 web 應用程序運行后台工作程序。 我使用 Npgsql 作為我的 EF Core 提供程序。
為了澄清起見,我已經為我的DbContext
注入了一個瞬態生命周期,並允許在我的連接字符串中進行池化,但是,每當我嘗試對其進行測試時,我都會收到以下錯誤:
Npgsql.NpgsqlOperationInProgressException:命令已經在進行中:[My Query Here]
我有我的Program
Class 設置如下:
public class Program
{
public static void Main(string[] args)
{
CreateHostBuilder(args).Build().Run();
}
public static IHostBuilder CreateHostBuilder(string[] args) =>
Host.CreateDefaultBuilder(args)
.ConfigureServices((hostContext, services) =>
{
// Get the configuration
IConfiguration config = hostContext.Configuration;
// DbContext
services.AddDbContext<MyDbContext>(options => options.UseNpgsql(config.GetConnectionString("PostgreSQLString")), ServiceLifetime.Transient);
services.AddHostedService<Worker>();
services.AddScoped<IDTOService, BackgroundDTOService>();
});
}
然后導致我的Worker
class
public class Worker : BackgroundService
{
private Logger logger;
public Worker(IServiceProvider services, IConfiguration configuration)
{
this.Services = services;
var optionsBuilder = new DbContextOptionsBuilder<MyDbContext>();
optionsBuilder.UseNpgsql(configuration.GetConnectionString("PostgreSQLString"));
var context = new StatPeekContext(optionsBuilder.Options);
this.logger = new Logger(new LogWriter(context));
}
public IServiceProvider Services { get; }
protected override async Task ExecuteAsync(CancellationToken stoppingToken)
{
this.logger.LogInformation("ExecuteAsync in Worker Service is running.");
await this.DoWork(stoppingToken);
}
private async Task DoWork(CancellationToken stoppingToken)
{
using (var scope = Services.CreateScope())
{
var context = scope.ServiceProvider.GetRequiredService<MyDbContext>();
var dtoService = scope.ServiceProvider.GetRequiredService<IDTOService>();
await dtoService.ProcessJSON(stoppingToken);
}
}
public override async Task StopAsync(CancellationToken cancellationToken)
{
this.logger.LogInformation("Worker service is stopping.");
await Task.CompletedTask;
}
}
這導致我的BackGroundDTOService
public class BackgroundDTOService : IDTOService
{
private int executionCount = 0;
private Logger logger;
private MyDbContext context;
private DbContextOptionsBuilder<MyDbContext> optionsBuilder;
public BackgroundDTOService(IConfiguration configuration, MyDbContext context)
{
this.optionsBuilder = new DbContextOptionsBuilder<MyDbContext>();
this.optionsBuilder.UseNpgsql(configuration.GetConnectionString("PostgreSQLString"));
this.logger = new Logger(new LogWriter(new MyDbContext(this.optionsBuilder.Options)));
this.context = context;
}
public async Task ProcessJSON(CancellationToken stoppingToken)
{
while (!stoppingToken.IsCancellationRequested)
{
this.executionCount++;
this.logger.LogInformation($"DTO Service is working. Count: {this.executionCount}");
this.ProcessTeams();
await Task.Delay(TimeSpan.FromSeconds(1), stoppingToken);
}
}
public void ProcessTeams()
{
// Add Any Franchises that don't exist
var franchiseDumps = this.context.RequestDumps.Where(rd => rd.Processed == false && rd.DumpType == "leagueteams");
foreach (RequestDump teamDump in franchiseDumps)
{
var league = this.context.Leagues.Include(l => l.Franchises).FirstOrDefault(l => l.Id == teamDump.LeagueID);
var teams = Jeeves.GetJSONFromKey<List<DTOTeam>>(teamDump.JsonDump, "leagueTeamInfoList");
foreach (DTOTeam team in teams)
{
this.UpdateFranchise(team, league);
}
this.logger.LogInformation($"DTO Service Processed League Teams on count {this.executionCount}");
}
this.context.SaveChanges();
}
當試圖獲得league
時,錯誤似乎立即發生在獲得franchiseDumps
轉儲后
您能否嘗試具體化查詢:
var franchiseDumps = this.context.RequestDumps.Where(rd => rd.Processed == false && rd.DumpType == "leagueteams").ToList();
有同樣的問題,意識到與 MSSQL 相比,Postgres 不支持多個活動結果集 (MARS)。
對我來說用外鍵獲取對象的另一種方法:
IEnumerable<Expense> objList = _db.Expenses;
foreach (var obj in objList.ToList())
{
obj.ExpenseCategory = _db.ExpenseCategories.FirstOrDefault(u => u.Id == obj.ExpenseCategoryId);
}
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