我正在使用ADO.Net填充数据表,该数据表填充方法已放入单独的存储库中。我将存储库/接口注入到测试页面模型中。页面模型方法“ OnPostUpdateAlarmDataTableAsync”需要调用接口并请求填充数据表。我想从填充此表的任务中返回结果,因此,如果任务由于某种原因而失败,那么我可以在UI上通知用户,我也想从页面模型中记录错误的详细信息,因为是调用线程。
当前的编译错误说“无法为隐式类型的变量分配void”,但是我尝试更改代码中的任何组合,但都无法正确编译。我想实现能够从异步操作中返回任务的相关信息,其中包含有关异常的详细信息。
接口:
public interface IAdoNetRepository
{
Task FillAlarmsDataTable();
}
仓库:
public class AdoNetRepository : IAdoNetRepository
{
public readonly IConfiguration _config;
public AdoNetRepository(IConfiguration config)
{
_config = config;
}
// Used for method below GetUserGroupsData()
public static SqlDataAdapter dataAdapter = new SqlDataAdapter();
public static DataTable alarmDataTable;
public async Task FillAlarmsDataTable()
{
string connectionString = _config.GetConnectionString("Data:DefaultConnection:ConnectionString");
try
{
SqlConnection connection = new SqlConnection(connectionString);
string cmdText1 = "SELECT * FROM [dbo].[Alarms] ORDER BY Name";
// Create a new data adapter based on the specified query.
dataAdapter = new SqlDataAdapter(cmdText1, connection);
// Populate a new data table and bind it to the BindingSource.
alarmDataTable = new DataTable
{
Locale = CultureInfo.InvariantCulture
};
await Task.Run(() => dataAdapter.Fill(alarmDataTable));
//dataAdapter.Fill(alarmDataTable);
return; // Return what ?
}
catch (Exception ex)
{
// Return the task with details of the exception
return; // Return what?
}
}
}
PageModel:
public class TestModel : PageModel
{
private readonly IAdoNetRepository _adoNetRepository;
public TestModel(IAdoNetRepository adoNetRepository)
{
_adoNetRepository = adoNetRepository;
}
public async Task<IActionResult> OnPostUpdateAlarmDataTableAsync()
{
// This gets squiggly line compile error
var result = await _adoNetRepository.FillAlarmsDataTable();
if (!result.Succeeded)
{
// log the exception returned from the task that failed!
}
return new JsonResult(result);
}
}
原始示例中的注释显示了您应该实际执行的操作。
您将需要创建一个模型来存储所需的信息。
就像是
/// <summary>
/// Represents the result of an ADO.Net operation.
/// </summary>
public class AdoNetResult {
private List<Exception> _errors = new List<Exception>();
public bool Succeeded { get; protected set; }
public IEnumerable<Exception> Errors => _errors;
public static AdoNetResult Success { get; } = new AdoNetResult { Succeeded = true };
public static AdoNetResult Failed(params Exception[] errors) {
var result = new AdoNetResult { Succeeded = false };
if (errors != null) {
result._errors.AddRange(errors);
}
return result;
}
}
但是,该接口需要重构
public interface IAdoNetRepository {
Task<AdoNetResult> FillAlarmsDataTable();
}
和实施
public async Task<AdoNetResult> FillAlarmsDataTable() {
string connectionString = _config.GetConnectionString("Data:DefaultConnection:ConnectionString");
try {
SqlConnection connection = new SqlConnection(connectionString);
string cmdText1 = "SELECT * FROM [dbo].[Alarms] ORDER BY Name";
// Create a new data adapter based on the specified query.
dataAdapter = new SqlDataAdapter(cmdText1, connection);
// Populate a new data table and bind it to the BindingSource.
alarmDataTable = new DataTable {
Locale = CultureInfo.InvariantCulture
};
await Task.Run(() => dataAdapter.Fill(alarmDataTable));
// Return what ?
return AdoNetResult.Success;
} catch (Exception ex) {
// Return the task with details of the exception
return AdoNetResult.Failed(ex);
}
}
完成后,原始代码应按预期工作
public async Task<IActionResult> OnPostUpdateAlarmDataTableAsync() {
var result = await _adoNetRepository.FillAlarmsDataTable();
if (!result.Succeeded) {
// log the exception returned from the task that failed!
//result.Errors
}
return new JsonResult(result);
}
一种替代方法是让它FillAlarmsDataTable
抛出可能遇到的任何异常
public Task FillAlarmsDataTable() {
string connectionString = _config.GetConnectionString("Data:DefaultConnection:ConnectionString");
SqlConnection connection = new SqlConnection(connectionString);
string cmdText1 = "SELECT * FROM [dbo].[Alarms] ORDER BY Name";
// Create a new data adapter based on the specified query.
dataAdapter = new SqlDataAdapter(cmdText1, connection);
// Populate a new data table and bind it to the BindingSource.
alarmDataTable = new DataTable {
Locale = CultureInfo.InvariantCulture
};
return Task.Run(() => dataAdapter.Fill(alarmDataTable));
}
捕获(捕获)正在使用的异常并做出相应的响应
public async Task<IActionResult> OnPostUpdateAlarmDataTableAsync() {
try {
await _adoNetRepository.FillAlarmsDataTable();
return Ok(); //200 OK
catch(Exception ex) {
//...log the exception returned from the task that failed!
return new ExceptionResult(ex, includeErrorDetail:true);
}
}
嗨,恩科西(Nkosi),非常感谢您的帮助,这绝对是很棒的:)