如何声明动态参数

此示例演示如何定义在运行时添加到 cmdlet 的动态参数。在此示例中，只要用户指定 Employee 开关参数，Department 参数就会添加到 cmdlet。有关动态参数的详细信息，请参阅 Cmdlet 动态参数。

定义动态参数

1. 在 cmdlet 类声明中，添加 System.Management.Automation.Idynamicparameters 接口，如下所示。

   public class SendGreetingCommand : Cmdlet, IDynamicParameters
   

2. 调用 System.Management.Automation.Idynamicparameters.Getdynamicparameters* 方法，该方法返回定义动态参数的对象。在此示例中，当指定 Employee 参数时调用该方法。

   public object GetDynamicParameters()
   {
       if (employee)
       {
         context= new SendGreetingCommandDynamicParameters();
         return context;
       }
       return null;
   }
   private SendGreetingCommandDynamicParameters context;
   

3. 声明一个定义要添加的动态参数的类。您可以使用用于声明静态 cmdlet 参数的属性来声明动态参数。

   public class SendGreetingCommandDynamicParameters
   {
     [Parameter]
     [ValidateSet ("Marketing", "Sales", "Development")]
     public string Department
     {
       get { return department; }
       set { department = value; }
     }
     private string department;
   }
   

例子

在此示例中，只要用户指定 Employee 参数，就会添加 Department 参数。 Department 参数是可选参数，ValidateSet 属性用于指定允许的参数。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Management.Automation;     // PowerShell assembly.

namespace SendGreeting
{
  // Declare the cmdlet class that supports the
  // IDynamicParameters interface.
  [Cmdlet(VerbsCommunications.Send, "Greeting")]
  public class SendGreetingCommand : Cmdlet, IDynamicParameters
  {
    // Declare the parameters for the cmdlet.
    [Parameter(Mandatory = true)]
    public string Name
    {
      get { return name; }
      set { name = value; }
    }
    private string name;

    [Parameter]
    [Alias ("FTE")]
    public SwitchParameter Employee
    {
      get { return employee; }
      set { employee = value; }
    }
    private Boolean employee;

    // Implement GetDynamicParameters to
    // retrieve the dynamic parameter.
    public object GetDynamicParameters()
    {
      if (employee)
      {
        context= new SendGreetingCommandDynamicParameters();
        return context;
      }
      return null;
   }
   private SendGreetingCommandDynamicParameters context;

    // Override the ProcessRecord method to process the
    // supplied user name and write out a greeting to
    // the user by calling the WriteObject method.
    protected override void ProcessRecord()
    {
      WriteObject("Hello " + name + "! ");
      if (employee)
      {
        WriteObject("Department: " + context.Department);
      }
    }
  }

  // Define the dynamic parameters to be added
  public class SendGreetingCommandDynamicParameters
  {
    [Parameter]
    [ValidateSet ("Marketing", "Sales", "Development")]
    public string Department
    {
      get { return department; }
      set { department = value; }
    }
    private string department;
  }
}

参见

• System.Management.Automation.RuntimeDefinedParameterDictionary
• System.Management.Automation.IDynamicParameters.GetDynamicParameters*
• Cmdlet 动态参数
• Windows PowerShell SDK