考虑以下带有 TestTable 和过程的 TestDb
USE TestDb
GO
--DROP TABLE dbo.TestTable
IF NOT EXISTS (SELECT 1 FROM sys.tables WHERE name = 'TestTable')
BEGIN
CREATE TABLE dbo.TestTable
(
RecordId int NOT NULL IDENTITY(1,1) PRIMARY KEY
, StringValue varchar(50) NULL
, DateValue date NULL
, DateTimeValue datetime NULL
, MoneyValue money NULL
, DecimalValue decimal(19,4) NULL
, IntValue int NULL
, BitValue bit NOT NULL
)
INSERT INTO dbo.TestTable
SELECT 'Test', CAST(GETDATE() AS DATE), GETDATE(), 100.15, 100.0015, 100, 1
UNION SELECT NULL, NULL, NULL, NULL, NULL, NULL, 0
END
GO
IF EXISTS (SELECT 1 FROM sys.procedures WHERE name = 'Get_TestTable')
DROP PROCEDURE dbo.Get_TestTable
GO
CREATE PROCEDURE dbo.Get_TestTable (@RecordId int = NULL) AS WAITFOR DELAY '00:00:30'; SELECT * FROM dbo.TestTable WHERE RecordId = ISNULL(@RecordId,RecordId);
GO
EXEC dbo.Get_TestTable @RecordId = NULL
当使用WebMatrix内置数据库查询助手时，您可以执行以下操作：
@{
string errorMessage = String.Empty;
int? RecordId = null;
IEnumerable<dynamic> rowsTestTable = null;
try
{
using (Database db = Database.Open("TestDb"))
{
rowsTestTable = db.Query("EXEC dbo.Get_TestTable @RecordId=@0",RecordId);
}
}
catch (Exception ex)
{
errorMessage = ex.Message;
}
}
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8" />
<title></title>
</head>
<body>
@if(errorMessage == String.Empty)
{
<table border="1">
<thead>
<tr>
<th>RecordId</th>
<th>StringValue</th>
<th>DateValue</th>
<th>DateTimeValue</th>
<th>MoneyValue</th>
<th>DecimalValue</th>
<th>IntValue</th>
<th>BitValue</th>
</tr>
</thead>
<tbody>
@foreach(var row in rowsTestTable)
{
<tr>
<td>@row["RecordId"]</td>
<td>@row["StringValue"]</td>
<td>@if(@row["DateValue"] != null){@Html.Raw(String.Format("{0:MM/dd/yyyy}",@row["DateValue"]));}</td>
<td>@if(@row["DateTimeValue"] != null){@Html.Raw(String.Format("{0:MM/dd/yyyy hh:mm:ss.fff tt}",@row["DateTimeValue"]));}</td>
<td>@if(@row["MoneyValue"] != null){@Html.Raw(String.Format("{0:c}",@row["MoneyValue"]));}</td>
<td>@row["DecimalValue"]</td>
<td>@row["IntValue"]</td>
<td>@row["BitValue"]</td>
</tr>
}
</tbody>
</table>
}
<p>@errorMessage</p>
<h4>No Additional Problem - On handling of DateValue</h4>
@try
{
foreach(var row in rowsTestTable)
{
<p>@if(row.DateValue != null){@Html.Raw(DateTime.Parse(row.DateValue.ToString()))}</p>
}
}
catch (Exception ex)
{
<p>@ex.Message</p>
}
<h4>No Additional Problem - On handling of MoneyValue (and other number values)</h4>
@try
{
foreach(var row in rowsTestTable)
{
<p>@if(row.MoneyValue != null){@Html.Raw(Double.Parse(row.MoneyValue.ToString()))}</p>
}
}
catch (Exception ex)
{
<p>@ex.Message</p>
}
</body>
</html>
这会产生超时过期错误，因为 WebMatrix Database.Query 帮助程序已修复默认的 30 秒 CommandTimeout。有什么方法可以将单个查询的默认时间覆盖为 5 分钟之类的吗？
由于没有找到解决方案，我根据大量搜索和尝试创建了自己的 SimpleQuery 助手，直到最终找到了一个代码参考 http://blogs.msdn.com/b/davidebb/archive/2009/10/29/using-c-dynamic-to-simplify-ado-net-use.aspx我能够理解和适应。
using System.Collections.Generic; // IEnumerable<dynamic>
using System.Data; // IDataRecord
using System.Data.SqlClient; // SqlConnection
using System.Dynamic; // DynamicObject
public class SimpleQuery
{
public static IEnumerable<dynamic> Execute(string connectionString, string commandString, int commandTimeout)
{
using (var connection = new SqlConnection(connectionString))
{
using (var command = new SqlCommand(commandString, connection))
{
command.CommandTimeout = commandTimeout;
connection.Open();
using (SqlDataReader reader = command.ExecuteReader())
{
foreach (IDataRecord record in reader)
{
yield return new DataRecordDynamicWrapper(record);
}
}
connection.Close();
}
}
}
public class DataRecordDynamicWrapper : DynamicObject
{
private IDataRecord _dataRecord;
public DataRecordDynamicWrapper(IDataRecord dataRecord) { _dataRecord = dataRecord; }
public override bool TryGetMember(GetMemberBinder binder, out object result)
{
result = _dataRecord[binder.Name];
return result != null;
}
}
}
因此，现在通过更改网络代码以使用新的 SimpleQuery 帮助器，我可以获得几乎相同的结果，但存在一些问题
@{
string errorMessage = String.Empty;
int? RecordId = null;
IEnumerable<dynamic> rowsTestTable = null;
try
{
string commandString = String.Format("dbo.Get_TestTable @RecordId={0}", RecordId == null ? "null" : RecordId.ToString()); // Problem 1: Have to use String.Format to embed the Parameters
rowsTestTable = SimpleQuery.Execute(System.Configuration.ConfigurationManager.ConnectionStrings["TestDb"].ConnectionString,commandString,300);
foreach(var row in rowsTestTable) { break; } // Problem 2: Have to force query execution here, so the error (if any) gets trapped here
}
catch (Exception ex)
{
errorMessage = ex.Message;
}
}
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8" />
<title></title>
</head>
<body>
@if(errorMessage == String.Empty)
{
<table border="1">
<thead>
<tr>
<th>RecordId</th>
<th>StringValue</th>
<th>DateValue</th>
<th>DateTimeValue</th>
<th>MoneyValue</th>
<th>DecimalValue</th>
<th>IntValue</th>
<th>BitValue</th>
</tr>
</thead>
<tbody>
@foreach(var row in rowsTestTable)
{
<tr>
@*<td>@row["RecordId"]</td>*@ <!-- Problem 3: Can't reference as row["FieldName"], so if any field names have spaces or other special characters, can't reference -->
<td>@row.RecordId</td>
<td>@row.StringValue</td>
<td>@if(@row.DateValue != null){@Html.Raw(String.Format("{0:MM/dd/yyyy}",@row.DateValue));}</td>
<td>@if(@row.DateTimeValue != null){@Html.Raw(String.Format("{0:MM/dd/yyyy hh:mm:ss.fff tt}",@row.DateTimeValue));}</td>
<td>@if(@row.MoneyValue != null){@Html.Raw(String.Format("{0:c}",@row.MoneyValue));}</td>
<td>@row.DecimalValue</td>
<td>@row.IntValue</td>
<td>@row.BitValue</td>
</tr>
}
</tbody>
</table>
}
<p>@errorMessage</p>
<h4>Additional Problem - Unexpected handling of DateValue</h4>
@try
{
foreach(var row in rowsTestTable)
{
<p>@if(row.DateValue != null){@Html.Raw(DateTime.Parse(row.DateValue.ToString()))}</p>
}
}
catch (Exception ex)
{
<p>@ex.Message</p>
}
<h4>Additional Problem - Unexpected handling of MoneyValue (and other number values)</h4>
@try
{
foreach(var row in rowsTestTable)
{
<p>@if(row.MoneyValue != null){@Html.Raw(Double.Parse(row.MoneyValue.ToString()))}</p>
}
}
catch (Exception ex)
{
<p>@ex.Message</p>
}
</body>
</html>
问题 1-3 在使用 SimpleQuery 帮助程序的第二个 Web 代码中进行了注释。我可以解决这些问题，但我仍然在努力解决为什么未检测到数字和日期值的 NULL 检查。
我希望能够帮助您正确检测这些内容，这样我就可以避免在使用 Double.Parse 或 DateTime.Parse 时出现后续错误。我也很感激 SimpleQuery 帮助器或您看到的其他任何内容的一般指示/改进。
提前致谢。
