我在 PowerShell v4.0(Windows 7 x64 SP1)上有一个 PowerShell 脚本,它创建了一个非常复杂的数据表。我希望能够很容易地将 DataTable 代码放在任何地方,所以我决定将它包装在一个简单的函数中,如下所示:
function Get-UserDataTable
{
$DataTable = New-Object -TypeName System.Data.DataTable -ArgumentList 'User';
$NewColumn = $DataTable.Columns.Add('Id',[System.Int32]);
$NewColumn.AllowDBNull = $false;
$NewColumn.Unique = $true;
$NewColumn = $DataTable.Columns.Add('FirstName',[System.String]);
$NewColumn.MaxLength = 64;
$NewColumn = $DataTable.Columns.Add('MiddleName',[System.String]);
$NewColumn.MaxLength = 64;
$NewColumn = $DataTable.Columns.Add('LastName',[System.String]);
$NewColumn.MaxLength = 64;
return $DataTable;
}
但是,该代码始终返回空对象。我试过
Write-Output $DataTable
, return $DataTable.Copy()
, 和 $DataTable
,但该函数始终为空。所以,我想我可以尝试添加一些行。我总是可以清除数据表,这样编码仍然会更少:
function Get-UserDataTable2
{
$DataTable = New-Object -TypeName System.Data.DataTable -ArgumentList 'User';
$NewColumn = $DataTable.Columns.Add('Id',[System.Int32]);
$NewColumn.AllowDBNull = $false;
$NewColumn.Unique = $true;
$NewColumn = $DataTable.Columns.Add('FirstName',[System.String]);
$NewColumn.MaxLength = 64;
$NewColumn = $DataTable.Columns.Add('MiddleName',[System.String]);
$NewColumn.MaxLength = 64;
$NewColumn = $DataTable.Columns.Add('LastName',[System.String]);
$NewColumn.MaxLength = 64;
$NewRow = $DataTable.NewRow();
$NewRow.Id = 1;
$NewRow.FirstName = 'Test';
$NewRow.MiddleName = '';
$NewRow.LastName = 'User';
$DataTable.Rows.Add($NewRow);
$NewRow = $DataTable.NewRow();
$NewRow.Id = 2;
$NewRow.FirstName = 'Other';
$NewRow.MiddleName = 'Test';
$NewRow.LastName = 'User';
$DataTable.Rows.Add($NewRow);
return $DataTable;
}
不。此函数返回
[System.Object[]]
包含个人 [System.Data.DataRow]
. DataRows 的对象数组。如何从 PowerShell 中的函数返回 DataTable?
最佳答案
正如 PerSerAl 评论中的链接所暗示的那样,该问题是由于 DataTable 不是可枚举的数据类型而引起的。要强制它可枚举,您可以使用一元逗号运算符将其作为单个元素放入数组中。数组是可枚举的。
function Get-UserDataTable
{
$DataTable = New-Object -TypeName System.Data.DataTable -ArgumentList 'User';
$NewColumn = $DataTable.Columns.Add('Id',[System.Int32]);
$NewColumn.AllowDBNull = $false;
$NewColumn.Unique = $true;
$NewColumn = $DataTable.Columns.Add('FirstName',[System.String]);
$NewColumn.MaxLength = 64;
$NewColumn = $DataTable.Columns.Add('MiddleName',[System.String]);
$NewColumn.MaxLength = 64;
$NewColumn = $DataTable.Columns.Add('LastName',[System.String]);
$NewColumn.MaxLength = 64;
return ,$DataTable;
}
关于PowerShell 函数不会返回 DataTable,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/35491390/