我正在尝试为我正在开发的Web应用程序运行后台工作者。我正在使用Npgsql作为EF Core提供程序。
为澄清起见,我为DbContext
注入了瞬态生命周期,并允许在连接字符串中进行池化,但是,每当我尝试对其进行测试时,都会出现以下错误:
Npgsql.NpgsqlOperationInProgressException:命令已经在执行中:[我在这里查询]
我这样设置了Program
类:
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>();
});
}
然后引导到我的Worker
班
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;
}
}
导致我的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();
}
[尝试获取franchiseDumps
时,似乎在紧紧抓住league
之后立即发生错误
您能否尝试实现查询:
var franchiseDumps = this.context.RequestDumps.Where(rd => rd.Processed == false && rd.DumpType == "leagueteams").ToList();