如何设置PowerShell类的默认输出 [英] How to set the default output of a PowerShell class
问题描述
我正在尝试创建一个从标准 [Data.DataTable]
类派生的PowerShell [DataTable]
类,以简化数据表的创建:
(另请参见: #11987
轻松加速[DataTable]构造函数和AddRow方法)
I am trying to create a PowerShell [DataTable]
class derived from the standard [Data.DataTable]
class to ease the creation of data tables:
(see also: #11987
Accelerated [DataTable] with easy constructor and AddRow method)
class DataTable : Data.DataTable {
[ValidateNotNullOrEmpty()][Data.DataTable]$DataTable
DataTable([Array]$ColumnNames) {
$This.DataTable = New-Object Data.DataTable
ForEach ($ColumnName in $ColumnNames) {
If ($ColumnName -is [System.Collections.IDictionary]) {
ForEach($Key in $ColumnName.Get_keys()) { $This.AddColumn($Key, $ColumnName[$Key]) }
} Else { $This.AddColumn($ColumnName) }
}
}
[Void]AddColumn([String]$ColumnName) {
$DataColumn = New-Object Data.DataColumn($ColumnName)
$This.DataTable.Columns.Add($DataColumn)
}
[Void]AddColumn([String]$ColumnName, [Type]$ColumnType = [String]) {
$DataColumn = New-Object Data.DataColumn($ColumnName, $ColumnType)
$This.DataTable.Columns.Add($DataColumn)
}
[Void]AddRow([Array]$Array) {
$DataRow = $This.DataTable.NewRow()
For ($i = 0; $i -lt $Array.Length; $i++) { $DataRow.Item($i) = $Array[$i] }
$This.DataTable.Rows.Add($DataRow)
}
[Void]AddRow([System.Collections.IDictionary]$Dictionary) {
$DataRow = $This.DataTable.NewRow()
ForEach ($Name in $Dictionary.get_Keys()) { $DataRow.Item($Name) = $Dictionary[$Name] }
$This.DataTable.Rows.Add($DataRow)
}
}
它可用于创建新的数据表:
It works for creating new data table:
$MyDataTable = [DataTable]('a', 'b', 'c')
$MyDataTable.AddRow(@(1,2,3))
但是要获得 $ DataTable
,需要做的事情:
But to get the $DataTable
in need to do:
$MyDataTable.DataTable
a b c
- - -
1 2 3
我希望它默认输出数据表 $ MyDataTable
并执行以下操作: .DataTable
I want it to output the data table by default $MyDataTable
and do things like this:.DataTable
$MyDataTable | ForEach-Object { ...
如何让我的班级默认返回 $ This.DataTable
?
(或者使用PowerShell类根本不可能吗?)
How can I let my class the return $This.DataTable
by default?
(or is this simply not possible with a PowerShell class?)
更新
我在下面解决了该班级中的一些(与问题无关)错误,以及来自 @Adam Luniewski 的答案a>.
class DataTable : Data.DataTable {
DataTable([Array]$ColumnNames) {
ForEach ($ColumnName in $ColumnNames) { $This.AddColumn($ColumnName) }
}
DataTable([System.Collections.IDictionary]$ColumnNameTypes) {
ForEach($Key in $ColumnNameTypes.Get_keys()) { $This.AddColumn($Key, $ColumnNameTypes[$Key]) }
}
[Void]AddColumn([String]$ColumnName) {
$DataColumn = New-Object Data.DataColumn($ColumnName)
$This.Columns.Add($DataColumn)
}
[Void]AddColumn([String]$ColumnName, [Type]$ColumnType = [String]) {
$DataColumn = New-Object Data.DataColumn($ColumnName, $ColumnType)
$This.Columns.Add($DataColumn)
}
[Void]AddRow([Array]$Array) {
$DataRow = $This.NewRow()
For ($i = 0; $i -lt $Array.Length; $i++) { $DataRow.Item($i) = $Array[$i] }
$This.Rows.Add($DataRow)
}
[Void]AddRow([System.Collections.IDictionary]$Dictionary) {
$DataRow = $This.NewRow()
ForEach ($Name in $Dictionary.get_Keys()) { $DataRow.Item($Name) = $Dictionary[$Name] }
$This.Rows.Add($DataRow)
}
}
推荐答案
您的新类正在扩展DataTable,因此它已经是DataTable.您不需要内部DataTable,并且可以对$ This(而不是$ This.DataTable)执行所有操作.我只将类的名称更改为MyDataTable并删除了内部DataTable:
Your new class is extending DataTable, so it already IS DataTable. You don't need inner DataTable and can perform all the operations on $This instead of $This.DataTable. I only changed the name of the class to MyDataTable and removed inner DataTable:
class MyDataTable : Data.DataTable {
MyDataTable([Array]$ColumnNames) {
ForEach ($ColumnName in $ColumnNames) {
If ($ColumnName -is [System.Collections.IDictionary]) {
ForEach($Key in $ColumnName.Get_keys()) { $This.AddColumn($Key, $ColumnName[$Key]) }
} Else { $This.AddColumn($ColumnName) }
}
}
[Void]AddColumn([String]$ColumnName) {
$DataColumn = New-Object Data.DataColumn($ColumnName)
$This.Columns.Add($DataColumn)
}
[Void]AddColumn([String]$ColumnName, [Type]$ColumnType = [String]) {
$DataColumn = New-Object Data.DataColumn($ColumnName, $ColumnType)
$This.Columns.Add($DataColumn)
}
[Void]AddRow([Array]$Array) {
$DataRow = $This.NewRow()
For ($i = 0; $i -lt $Array.Length; $i++) { $DataRow.Item($i) = $Array[$i] }
$This.Rows.Add($DataRow)
}
[Void]AddRow([System.Collections.IDictionary]$Dictionary) {
$DataRow = $This.NewRow()
ForEach ($Name in $Dictionary.get_Keys()) { $DataRow.Item($Name) = $Dictionary[$Name] }
$This.Rows.Add($DataRow)
}
}
$MyDataTable = [MyDataTable]('a', 'b', 'c')
$MyDataTable.AddRow(@(1,2,3))
$MyDataTable #works now:
a b c
- - -
1 2 3
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